question
Caries
answer
caused by streptococcus mutans and streptococcus sobrinus
question
Periodontitis
answer
chronic inflammation at the gingiva and bone destruction around tooth
caused by porphyromonas gingivalis, fusobacterium nucleatum, actinomycetes actinomyeticomitans
6th most prevalent health condition in the world
caused by porphyromonas gingivalis, fusobacterium nucleatum, actinomycetes actinomyeticomitans
6th most prevalent health condition in the world
question
Oral Thrush
answer
inflammation in mouth
caused by overgrowth of candida albicans
associated with immune deficiencies
caused by overgrowth of candida albicans
associated with immune deficiencies
question
Endodontitis
answer
inflammation at root of the tooth
caused by porphyromonas endodontalis, enterococcus faecalis
caused by porphyromonas endodontalis, enterococcus faecalis
question
Kaposi's Sarcoma
answer
cancer of endothelium of mouth
caused by combination of infection with Human Herpes Virus 8 and immune deficiency
caused by combination of infection with Human Herpes Virus 8 and immune deficiency
question
Lymphoma of Head and Neck
answer
caused by Epstein Barr Virus
infects over 90% of humans
only in some does it cause lymphomas
infects over 90% of humans
only in some does it cause lymphomas
question
Oral Squamous Cell Carcinoma
answer
cancer at epithelium of mouth caused by human papilloma virus (HPV)
question
Pneumonia
answer
lung infection caused by streptococcus pneumoniae
question
Oral Absesses
answer
deep tissue infection caused by staphylococcus aureus
question
tuberculosis
answer
lung infection caused by mycobacterium tuberculosis
question
Greatest Achievement of Microbiology
answer
dramatic decrease in mortality due to infectious diseases because of:
sanitation
better nutrition
antibiotics
vaccines
sanitation
better nutrition
antibiotics
vaccines
question
microorganisms
answer
central to the biosphere
outnumber our own cells 3:1
outnumber our own cells 3:1
question
bacteriophages
answer
viruses that infect microorganisms of our body
outnumber microorganisms 10:1
outnumber microorganisms 10:1
question
four classes of macromolecules in every cell
answer
proteins - composed of amino acids
nucleic acids - composed of nucleotides
lipids - composed of fatty acids
polysaccharides - composed of sugars
nucleic acids - composed of nucleotides
lipids - composed of fatty acids
polysaccharides - composed of sugars
question
Key Bacterial Structures
answer
Cytoplasmic Membrane
Cytoplasm
Nucleoid
Ribosomes
Cell Wall
Cytoplasm
Nucleoid
Ribosomes
Cell Wall
question
Cytoplasmic Membrane
answer
aka cell membrane
separates inside of cell from outside environment
doesn't contain steroids
responsible for electron transport and energy production
contains transport proteins, enzymes, secretion devices, and shape determining proteins
75% protein to 25% phospholipid
separates inside of cell from outside environment
doesn't contain steroids
responsible for electron transport and energy production
contains transport proteins, enzymes, secretion devices, and shape determining proteins
75% protein to 25% phospholipid
question
cytoplasm
answer
fluid that fills the cell
contains chromosomes, mRNA, ribosomes, proteins, and metabolites
contains chromosomes, mRNA, ribosomes, proteins, and metabolites
question
Nucleoid
answer
non-membrane bound area with single double stranded circular DNA chromosome
question
Ribosomes
answer
30S + 50S = 70S ribosome
machinery for protein synthesis and cell growth
machinery for protein synthesis and cell growth
question
Cell Wall
answer
present in nearly all microbes (structural strength)
contains peptidoglycan in bacteria
contains pseudoglycans in archaea
contains glucans in yeast
mycoplasma bacteria do not have a cell wall
contains peptidoglycan in bacteria
contains pseudoglycans in archaea
contains glucans in yeast
mycoplasma bacteria do not have a cell wall
question
Gram Negative vs Gram Positive Bacteria
answer
negative = has outer membrane outside cell wall
positive = does not have this outer membrane
positive = does not have this outer membrane
question
Anton van Leeuwenhoek
answer
first to describe bacteria using microscopes
constructured microscopes that allowed scientists to see these organisms too small for the naked eye
constructured microscopes that allowed scientists to see these organisms too small for the naked eye
question
electron microscope
answer
heralded a new understanding of structures of microbes that could not be seen previously
question
Louis Pasteur
answer
discovered that living organisms discriminate between optical isomers
discovered alcoholic fermentation is a biologically mediated process (not merely chemical)
disproved theory of spontaneous generation
developed vaccines of anthrax, fowl cholera, and rabies
discovered alcoholic fermentation is a biologically mediated process (not merely chemical)
disproved theory of spontaneous generation
developed vaccines of anthrax, fowl cholera, and rabies
question
spontaneous generation
answer
hypothesis that living organisms can originate from non-living matter
question
Louis Pasteur disproving spontaneous generation
answer
a sterile media could be contaminated with and grow bacteria only if the sterile media is exposed to air that has bacteria
question
Robert Koch
answer
discovered microorganisms were the cause of anthrax
announced the infectious cause of tuberculosis
discovered the bacterial colony
developed method to grow isolated colonies of bacteria
developed Koch's Postulates
announced the infectious cause of tuberculosis
discovered the bacterial colony
developed method to grow isolated colonies of bacteria
developed Koch's Postulates
question
Importance of the bacterial colony
answer
a single bacterial colony on day 2 represents a single bacterial cell deposited on day 0
question
Koch's Postulates
answer
1. suspected pathogen must be present in all cases of the disease and absent from healthy animals
2. the suspected pathogen must be grown in pure culture
3. cells from pure culture must cause disease in a healthy animal
4. suspected pathogen must be reisolated and shown to be the same as the original
2. the suspected pathogen must be grown in pure culture
3. cells from pure culture must cause disease in a healthy animal
4. suspected pathogen must be reisolated and shown to be the same as the original
question
two types of microbial cells
answer
prokaryote - bacteria and archae
eukaryote - fungi and protozoans
eukaryote - fungi and protozoans
question
Archaea
answer
prokaryotic microbe different from bacteria
may have been the first forms of life on earth
live in extreme environment
may have been the first forms of life on earth
live in extreme environment
question
Methanogens
answer
archaea that generate methane
question
halophiles
answer
archaea that thrive in high salt environments
question
thermophiles
answer
archaea that thrive in high heat environments
question
acidophiles
answer
arachaea that thrive in high acid environments
question
microbial symbiosis
answer
examples include mitochondria and chloroplasts
free-living bacterial cells that established stable residency in cells of Eukarya eons ago
mitochondria have their own ribosomes (70S) and are though to be derived from specific lineages of bacteria
free-living bacterial cells that established stable residency in cells of Eukarya eons ago
mitochondria have their own ribosomes (70S) and are though to be derived from specific lineages of bacteria
question
mitochondria
answer
vary in number per cell
has a double membrane
folded internal membrane called Cristae contain enzymes for respiration and ATP production
matrix contains enzymes for citric acid cycle
has a double membrane
folded internal membrane called Cristae contain enzymes for respiration and ATP production
matrix contains enzymes for citric acid cycle
question
mtDNA Expression
answer
37 essential genes required for oxidative phosphorylation (13 proteins, 22 tRNAs, 2 rRNAs)
gene expression alone involves >100 nuclear genes
gene expression alone involves >100 nuclear genes
question
Coccus
answer
round
question
bacillus
answer
rod shaped
question
spirillum
answer
loose spiral
question
spirochete
answer
tight spiral
question
budding
answer
has a stalk (generally mounted on something)
question
hyphae
answer
not mounted
question
filamentous
answer
chains of cells
question
strepto
answer
clusters of cells
question
staphylo
answer
two cells together
question
diplo
answer
causes dental caries
question
streptococcus mutans
answer
simple transporters
phosphotransferase-type transporters
ABC (ATP-binding cassette) transporters
phosphotransferase-type transporters
ABC (ATP-binding cassette) transporters
question
At Least 3 Types of Prokaryotic Transporters
answer
typically use energy of proton motive force to transport the substance
question
simple transporters
answer
energy comes from cytoplasmic membrane
nutrient transported in is phosphorylated, using a high energy phosphate group
nutrient transported in is phosphorylated, using a high energy phosphate group
question
phosphotransferase group translocation
answer
responsible for transporting glucose, fructose, and mannose
five proteins required
energy derived from phosphoenolpyruvate
five proteins required
energy derived from phosphoenolpyruvate
question
phosphotransferase system in E. Coli
answer
three interacting components
energy from proton motive force, ATP, or other energy-rich substance
200 different systems identified in prokaryotes
involved in the uptake of organic compounds, inorganic nutrients, and trace metals
high substrate specificity
contains periplasmic binding proteins
energy from proton motive force, ATP, or other energy-rich substance
200 different systems identified in prokaryotes
involved in the uptake of organic compounds, inorganic nutrients, and trace metals
high substrate specificity
contains periplasmic binding proteins
question
ABC (ATP-Binding Cassette) Transporters
answer
export proteins out of prokaryotic cells and insert into prokaryotic membranes
specific in types of proteins exported
specific in types of proteins exported
question
translocases
answer
exports proteins and inserts integral membrane proteins into the membrane
7 proteins involved
7 proteins involved
question
SEC Translocase System
answer
common in pathogenic bacteria
secreted protein translocated directly into host
often a virulence factor
secreted protein translocated directly into host
often a virulence factor
question
Type III secretion system
answer
peptidoglycan and teichoic acid (200-800 angstroms thick)
stains red typically
peptidoglycan interbridge is often pentaglycine
stains red typically
peptidoglycan interbridge is often pentaglycine
question
Gram Positive Bacteria
answer
peptidoglycan and an outer membrane
stains purple typically
peptidoglycan interbridge is often a direct link between one tetrapeptide that contains a DAP and the other tetrapeptide
stains purple typically
peptidoglycan interbridge is often a direct link between one tetrapeptide that contains a DAP and the other tetrapeptide
question
Gram Negative Bacteria
answer
alternating repeats of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) linked by beta 1-4 glycosidic bond
NAM is crosslinked by peptides between strands
many sheets present depending on the organism
NAM is crosslinked by peptides between strands
many sheets present depending on the organism
question
Peptidoglycan
answer
produced by our body
destroys peptidoglycan, leading to cell lysis of the bacteria
destroys peptidoglycan, leading to cell lysis of the bacteria
question
Lysozyme
answer
L-Alanine
D-Alanine
D-Glutamic Acid
Either Lysine or diaminopimelic acid (DAP)
D-Alanine
D-Glutamic Acid
Either Lysine or diaminopimelic acid (DAP)
question
Tetrapeptide Bound to NAM
answer
links one tetrapeptide with tetrapeptide of other chain, leading to strength and rigidity of wall
question
Peptidoglycan Interbridge
answer
prevents cross-linkage of cell wall peptidoglycan
weakens the cell wall
much less effective against gram negative peptidoglycan than gram positive
weakens the cell wall
much less effective against gram negative peptidoglycan than gram positive
question
Penicillin
answer
hydrophobic alcohol that facilitates transport of new glycan units across cytoplasmic membrane to form peptidoglycan
required for peptidoglycan synthesis
required for peptidoglycan synthesis
question
Bactoprenol
answer
inhibits the process of bactoprenol dependent peptidoglycan synthesis (gram-positive bacteria)
one of the few remaining drugs for treatment of multi-resistant gram positive infections
predominantly binds to D-alanyl-D-alanine part of the pentapeptide involved in transpeptidation
originally from streptomyces orientalis
one of the few remaining drugs for treatment of multi-resistant gram positive infections
predominantly binds to D-alanyl-D-alanine part of the pentapeptide involved in transpeptidation
originally from streptomyces orientalis
question
vancomycin
answer
AKA Penicillin-Binding Proteins (PBP)
targets for penicillin and other Beta-lactam antibiotics
targets for penicillin and other Beta-lactam antibiotics
question
Carboxypeptidases and Transpeptidases
answer
joining of two layers of peptidoglycan via peptides from each layer
starts with a pentapeptide of one layer and tetrapeptide of another
DAP is joined to the penultimate D-alanine
other D-alanine is lost from the pentapeptide to yield tetrapeptide on both layers
starts with a pentapeptide of one layer and tetrapeptide of another
DAP is joined to the penultimate D-alanine
other D-alanine is lost from the pentapeptide to yield tetrapeptide on both layers
question
transpeptidation
answer
first microbial enzyme discovered that destroys beta lactam penicillin
new beta-lactamases have evolved that inactivate the second generation of antibiotics that were developed to beat the first beta lactamases
890 unique beta-lactamases have been discovered
new beta-lactamases have evolved that inactivate the second generation of antibiotics that were developed to beat the first beta lactamases
890 unique beta-lactamases have been discovered
question
Beta-Lactamases
answer
New Delhi metallo-beta-lactamase-1
encoded on 180 kb plasmid with multiple resistance genes
hydrolyzes penicillins and cephalosporins
another beta-lactamase on the same plasmid inactivates erythromycin, ciproflaxacin, and chloramphenicol
encoded on 180 kb plasmid with multiple resistance genes
hydrolyzes penicillins and cephalosporins
another beta-lactamase on the same plasmid inactivates erythromycin, ciproflaxacin, and chloramphenicol
question
NDM-1
answer
associated with peptidoglycan of gram positive bacteria
function in adherance
binds Mg++ for the cell
function in adherance
binds Mg++ for the cell
question
Teichoic Acids
answer
1. contains glycerols repeated again and again and linked by phosphates with D-ala and D-glucose
2. contains ribitols repeated again and again linked by phosphates with D-ala and D-glucose
3. lipoteichoic - contains glycerols or ribitols with a terminal fatty acid that is integrated into the cytoplasmic membrane
2. contains ribitols repeated again and again linked by phosphates with D-ala and D-glucose
3. lipoteichoic - contains glycerols or ribitols with a terminal fatty acid that is integrated into the cytoplasmic membrane
question
3 Types of Teichoid Acid
answer
acid fast bacteria with mycolic acid layer exterior to peptidoglycan (mycobacteria outer membrane)
peptidoglycan is bound with arabinogalactan
peptidoglycan is bound with arabinogalactan
question
Mycobacteria
answer
lipopolysaccharide
proteins
lipoproteins
phospholipids
type I, II, III, IV, and V secretion devices
can be physiologically toxic to the host during an infection, therefore often referred to as endotoxin
proteins
lipoproteins
phospholipids
type I, II, III, IV, and V secretion devices
can be physiologically toxic to the host during an infection, therefore often referred to as endotoxin
question
Outer Membrane of Gram Negative Bacteria
answer
disseminated intravascular coagulation
follows release of large amounts of endotoxin into blood stream
follows release of large amounts of endotoxin into blood stream
question
Shwartzman Reaction
answer
shed large amounts of lipooligosaccharide (LOS), resulting in fever and severe symptoms
LOS lacks the O-antigen portion of LPS, but still has core polysaccharide plus lipid A
LOS lacks the O-antigen portion of LPS, but still has core polysaccharide plus lipid A
question
Neisseria Bacteria
answer
often called repeat polysaccharide or "O-antigen"
exterior portion of lipopolysaccharides on the outer membrane of gram negative bacteria
has various six carbon sugar motifs that are repeated again and again
exterior portion of lipopolysaccharides on the outer membrane of gram negative bacteria
has various six carbon sugar motifs that are repeated again and again
question
"O" specific polysaccharide
answer
middle portion of lipopolysaccharides on the outer membrane of gram negative bacteria
contains: ketodeoxyoctonate (KDO), heptoses, glucose, galactose, N-acetylglucosamine (NAG)
contains: ketodeoxyoctonate (KDO), heptoses, glucose, galactose, N-acetylglucosamine (NAG)
question
core polysaccharide
answer
inner portion of lipopolysaccharides on the outer membrane of gram negative bacteria
contains: diphospho-(NAG)2 with fatty acids attached
contains: diphospho-(NAG)2 with fatty acids attached
question
Lipid A
answer
integrated with both leaflets of the outer membranes
provide a channel to shuttle small nutrients from the outside to the inside
provide a channel to shuttle small nutrients from the outside to the inside
question
Porin Proteins
answer
space between membranes
contains other proteins, mainly for transport
contains other proteins, mainly for transport
question
periplasm
answer
wall-less bacteria that can survive in isotonic solutions, but not hypotonic solutions
they lyse in hypotonic solutions
they lyse in hypotonic solutions
question
Protoplasts
answer
produce unusually tough membranes
some live in osmotically protected habitats, such as the animal body (mycoplasma bacteria)
some evolve to survive in an animal body due to selective pressure L-forms of Penicillin (these are penicillin resistant)
some live in osmotically protected habitats, such as the animal body (mycoplasma bacteria)
some evolve to survive in an animal body due to selective pressure L-forms of Penicillin (these are penicillin resistant)
question
Prokaryotes that are naturally free-living protoplasts
answer
alcohol can readily penetrate the lipid rich outer membrane of gram negative bacteria and extract insoluble crystal violet-iodine complex from cell
question
Gram Stain Reaction
answer
multicellular movement of bacteria across a surface
powered by rotating helical flagella
powered by rotating helical flagella
question
Swarming
answer
movement of individual bacteria in liquid
powered by rotating flagella
powered by rotating flagella
question
Swimming
answer
surface movement of bacteria
powered by extension of pili, which attach to surface and retract, pulling cell closer
powered by extension of pili, which attach to surface and retract, pulling cell closer
question
Twitching
answer
active surface movement that does not require flagella or pili and involves focal-adhesion complexes
question
Gliding
answer
passive surface translocation
powered by growth and facilitated by a surfactant
powered by growth and facilitated by a surfactant
question
Sliding
answer
often virulence factors in pathogens
rotates at the expense of a proton motive force (1000 protons per rotation)
made up of flagellin
speed of about 60 cell lengths/second can be achieved
rotates at speed of up to 300 rps
rotates at the expense of a proton motive force (1000 protons per rotation)
made up of flagellin
speed of about 60 cell lengths/second can be achieved
rotates at speed of up to 300 rps
question
Flagella
answer
powerful stimulant of host innate immune response
question
flagellin
answer
counterclockwise rotation of flagella
clockwise rotation of flagella (causes tuft of flagella to spread)
clockwise rotation of flagella (causes tuft of flagella to spread)
question
run vs tumbling
answer
directed movement of organisms in response to chemicals
controlled by network of cell associated sensory and response proteins
controlled by network of cell associated sensory and response proteins
question
Chemotaxis (or phototaxis)
answer
movement directed towards the highest concentration of the chemical signal
question
Positive Chemotaxis
answer
movement directed away from the highest concentration of the chemical signal
question
Negative Chemotaxis
answer
filament of flagella
induces antibodies of our immune system (anti-H-antigen antibodies)
induces antibodies of our immune system (anti-H-antigen antibodies)
question
H-antigen
answer
Monotrichous - single flagellum
Amphitrichous - bipolar flagella
Iophotrichous - tufted flagella
Peritrichous - flagella that surround the perimeter
Amphitrichous - bipolar flagella
Iophotrichous - tufted flagella
Peritrichous - flagella that surround the perimeter
question
Types of Flagella
answer
short filament proteins used for attachment
some human pathogens have these as virulence factors (Bordetella pertussis)
some human pathogens have these as virulence factors (Bordetella pertussis)
question
Fimbriae
answer
long filaments that function in conjugation with other bacteria of same species
composed of protein subunit (pilin)
up to 150 per cell
both gram positive and negative bacteria
involved in attachments to tissue including salivary components
may be involved in movement
some viruses that infect bacteria use these as receptors
composed of protein subunit (pilin)
up to 150 per cell
both gram positive and negative bacteria
involved in attachments to tissue including salivary components
may be involved in movement
some viruses that infect bacteria use these as receptors
question
Pili
answer
two dimensional arrays of proteins
selective sieve
allows passage of low MW substances, while excluding large molecules
selective sieve
allows passage of low MW substances, while excluding large molecules
question
S-layers
answer
rigid polysaccharide layers firmly attached to cell
involved in attachment and prevent phagocytosis
involved in attachment and prevent phagocytosis
question
Capsules
answer
diffuse, amorphous, less compact polysaccharide mix
involved in attachment and prevent phagocytosis
involved in attachment and prevent phagocytosis
question
Slime Layer
answer
polysaccharides - streptococcus pneumoniae
hyaluronic acid - streptococcus pyogenes
poly-D-glutamic acid-polypeptides - Bacillus anthracis
dextran and levan-polysaccharides - streptococcus mutans
hyaluronic acid - streptococcus pyogenes
poly-D-glutamic acid-polypeptides - Bacillus anthracis
dextran and levan-polysaccharides - streptococcus mutans
question
Examples of Capsule/Slime Layer/S-Layer Types
answer
promotes adherance to teeth and its development is associated with caries tooth disease
glucosyl transferase is the enzyme that converts sucrose to:
polymer of glucose with alpha-1-6/alpha-1-3 bonds (dextran)
polymer of fructos with beta-2-6/beta-1-2 bonds (fructan)
glucosyl transferase is the enzyme that converts sucrose to:
polymer of glucose with alpha-1-6/alpha-1-3 bonds (dextran)
polymer of fructos with beta-2-6/beta-1-2 bonds (fructan)
question
Capsule/Slime Layer of S. mutans
answer
good candidate for human caries vaccine
released by S.Mutans and S.sanguis (cause of caries)
released by S.Mutans and S.sanguis (cause of caries)
question
glucosyl transferase of S. Mutans
answer
GTF B - catalyses synthesis of insoluble glucan from sucrose (mainly alpha-1,3-glucose moieties)
GTF C - synthesizes both alpha-1,3 and alpha-1,6-linked glucans
GTF D - synthesizes a water-soluble glucan of predominantly alpha-1,6-linked glucans
GTF C - synthesizes both alpha-1,3 and alpha-1,6-linked glucans
GTF D - synthesizes a water-soluble glucan of predominantly alpha-1,6-linked glucans
question
3 isoenzymes of GTF
answer
composed of high molecular weight polymers (ie volutin, polybetahydroxybutyric acid)
produced under conditions of unbalanced growth
produced under conditions of unbalanced growth
question
Storage Granules
answer
aka metachromatic granule
stains reddish violet with toluidine blue
stains reddish violet with toluidine blue
question
volutin
answer
polymer of C4 fatty acid
question
polybetahydroxybutyric acid
answer
polymer of glucose (alpha-1,4 and alpha-1,6 bonds)
stains red with potassium iodide
glycogen phosphorylase breaks this down for glucose in times of carbohydrate deficiency for the bacteria (what causes s. mutans to still cause caries overnight)
stains red with potassium iodide
glycogen phosphorylase breaks this down for glucose in times of carbohydrate deficiency for the bacteria (what causes s. mutans to still cause caries overnight)
question
Glycogen Storage Granules
answer
highly resistant differentiated bacterial cell produced by certain gram positive bacteria
several species can survive environmental insults through spore formation
resistant to heat, drying, radiation, and chemicals
difficult to stain
can germinate a live cell even after many decades, centuries, or millennia
several species can survive environmental insults through spore formation
resistant to heat, drying, radiation, and chemicals
difficult to stain
can germinate a live cell even after many decades, centuries, or millennia
question
endospore
answer
occurs when growth slows due to lack of nutrients
involves more than 500 genes and takes about 10 hours
involves more than 500 genes and takes about 10 hours
question
Sporulation
answer
Bacillus - aerobic
Clostridium - anaerobic
Clostridium - anaerobic
question
Species that Produce Endospores
answer
the reason for autoclaves and are killed under autoclave conditions (120C for 20 min under 15lb of pressure)
uniquely contain dipicolinic acid
pH is one unit lower than usual
uniquely contain dipicolinic acid
pH is one unit lower than usual
question
spores
answer
exosporium - outermost layer of lipoprotein
coat - very stable keratin-like protein
cortex - thickest layer; composed of peptidoglycan with fewer peptide crosslinks
core wall - peptidoglycan
coat - very stable keratin-like protein
cortex - thickest layer; composed of peptidoglycan with fewer peptide crosslinks
core wall - peptidoglycan
question
four layers of endospore
answer
protection of DNA from ultraviolet radiation, dessication, and dry heat
serves as a carbon and energy source during germination
serves as a carbon and energy source during germination
question
Role of Small Acid-Soluble Proteins in Endospores
answer
present in spores
binds up high levels of calcium
binds up high levels of calcium
question
dipicolinic
answer
occurs with nutritional and environmental normality
emergence of vegetative cell is result of endospore activation, germination, and subsequent outgrowth
process takes about 90 minutes
emergence of vegetative cell is result of endospore activation, germination, and subsequent outgrowth
process takes about 90 minutes
question
germination
answer
utilize energy rich compounds for anabolism and catabolism
chemoorganotrophs - obtain energy from oxidation of organic compounds
chemolithotrophs - obtain energy from oxidation of inorganic compounds
chemoorganotrophs - obtain energy from oxidation of organic compounds
chemolithotrophs - obtain energy from oxidation of inorganic compounds
question
chemotrophic organisms
answer
ATP generation depends on substrate level phosphorylation within a single metabolic pathway involved in catabolism of organic molecules
example is glycolysis
example is glycolysis
question
Fermentation
answer
produces lactic acid as fermentation product in the oral cavity because of lactate dehydrogenase
this acid is what produces carries
this acid is what produces carries
question
Glycolysis in s. mutans
answer
terminal enzyme in fermentation
question
lactate dehydrogenase
answer
ATP generation depends on transferring electrons out of one catabolic pathway via an intermediary into an electron transfer system
this produces a proton motive force which is used to produce ATP
Terminal electron acceptor:
aerobic - O2
anaerobic - molecule other than O2
this produces a proton motive force which is used to produce ATP
Terminal electron acceptor:
aerobic - O2
anaerobic - molecule other than O2
question
Respiration
answer
byproducts of using O2 (hydrogen peroxide and superoxide) are toxic
superoxide is a common toxic oxygen species
superoxide is a common toxic oxygen species
question
Toxicity of Aerobic Respiration
answer
aerobic bacteria use catalase, peroxidase, and superoxide dismutase to protect itself
anaerobic bacteria are not protected from the byproducts (eg. porphyromonas gingivalis)
anaerobic bacteria are not protected from the byproducts (eg. porphyromonas gingivalis)
question
Protection of Aerobic Respiration Toxicity
answer
both catabolic and anabolic
Citric Acid Cycle is an example
Citric Acid Cycle is an example
question
amphibolic
answer
increase in mass and/or number
rapid and occurs by binary fission
rapid and occurs by binary fission
question
Microbial Growth
answer
Lag Phase - prep for binary fission
Log (Exponential) Phase - increase in mass, then number dependent on generation time and growth rate
Stationary Phase
Death Phase
Log (Exponential) Phase - increase in mass, then number dependent on generation time and growth rate
Stationary Phase
Death Phase
question
Bacterial Growth Phases
answer
Direct Microscopic Count
Plate Count Method (Spread-Plate or Pour-Plate)
Spectrophotometric Method
Plate Count Method (Spread-Plate or Pour-Plate)
Spectrophotometric Method
question
3 Reliable Methods for determining bacterial concentration
answer
stops cell growth, but does not kill/lyse the cells
question
Bacteriostatic
answer
stops cell growth and kills cells, but does not lyse them
question
Bacteriocidal
answer
stops cell growth, kills cells and lyses them
question
Bacteriolytic
answer
required oxygen
question
Obligate Aerobes
answer
not required oxygen, but will enhance growth
question
Facultative Aerobes
answer
required oxygen, but at lower levels than atmospheric
question
Microaerophilic Aerobes
answer
oxygen not required, and will not enhance growth
s mutans
s mutans
question
Aerotolerant Anaerobes
answer
oxygen is harmful or lethal
porphyromonas gingivalis
porphyromonas gingivalis
question
Obligate Anaerobes
answer
reducing agent that can be added to a medium to test an organism's requirement for oxygen
question
thioglycollate
answer
2 H2O2 >> 2 H2O + O2
converts hydrogen peroxide to water and oxygen
converts hydrogen peroxide to water and oxygen
question
Catalase
answer
H2O2 + NADH + H+ >> 2 H2O + NAD+
converts hydrogen peroxide to water
converts hydrogen peroxide to water
question
Peroxidase
answer
2 O2- + 2 H+ >> H2O2 + O2
converts superoxides to hydrogen peroxides
converts superoxides to hydrogen peroxides
question
Superoxide Dismutase
answer
converts superoxides to hydrogen peroxides
question
Superoxide Reductase
answer
used to differentiate between streptococcus and staphylococcus isolates
presence of bubbles indicates action of catalase and the presence of streptococcus isolates
presence of bubbles indicates action of catalase and the presence of streptococcus isolates
question
Catalase Test
answer
Temperature
pH
water (osmotic)
pH
water (osmotic)
question
Environment Effects on Microbial Growth
answer
cardinal temperatures = minimum, optimum, and maximum temperatures at which an organism grows
psychrophile - <0-12C
mesophile - <10-50C
thermophile - 40-70C
hyperthermophile - 65-100C
extreme hyperthermophile - 90-110C
psychrophile - <0-12C
mesophile - <10-50C
thermophile - 40-70C
hyperthermophile - 65-100C
extreme hyperthermophile - 90-110C
question
Temperature and Microbial Growth
answer
most human microbes - pH 5-8 (optimum of 7)
acidophiles - love acidic environment (eg. lactobacilli grow best at pH 5.5)
acidophiles - love acidic environment (eg. lactobacilli grow best at pH 5.5)
question
pH and Microbial Growth
answer
dental plaque is localized biofilm, containing S mutans
S mutans can produce lactic acid in presence of sucrose or glucose
causes demineralization of the of the tooth
S mutans can produce lactic acid in presence of sucrose or glucose
causes demineralization of the of the tooth
question
pH and S mutans
answer
ability of oral bacteria to produce acid in presence of glucose
Factors:
presence of lactic acid producing bacteria
adherence of bacteria to tooth
production of antibodies for adherence factors
buffering capacity of saliva
Factors:
presence of lactic acid producing bacteria
adherence of bacteria to tooth
production of antibodies for adherence factors
buffering capacity of saliva
question
Stephan's Curve
answer
microbes that grow in very dry environments
water activity limits organism when dissolved solute concentration increases
countered by production of intracellular compatible solute by the cell that maintain positive water balance
water activity limits organism when dissolved solute concentration increases
countered by production of intracellular compatible solute by the cell that maintain positive water balance
question
Xerophiles
answer
grow best at reduced water potential
question
Halophiles
answer
require high levels of salts for growth
question
Extreme Halophiles
answer
can tolerate some reduction in water activity, but generally grow best in absence of added solute
question
Halotolerant Organisms
answer
time for one generation
question
generation time
answer
DNA replication
Cell elongation
Septum formation
completion of septum with wall formation
cell separation
Cell elongation
Septum formation
completion of septum with wall formation
cell separation
question
Microbial Growth Levels
answer
the keys to cell division and chromosome replication in bacteria
interact to form division apparatus in the cell called divisome
interact to form division apparatus in the cell called divisome
question
Fts Proteins
answer
defines the division plane in prokaryotes
question
FtsZ
answer
define cell shape
question
Mre Proteins
answer
penicillin binding protein required for penicillin action
question
FtsI
answer
anchor protein
question
FtsA
answer
dependent on autolysins-enzymes, which degrade existing peptidoglycan
question
Cell Wall Synthesis and Dividing Cells
answer
contiguous coding regions
upstream regulatory regions
transcription leads to polycistronic RNA (RNA with several coding regions)
upstream regulatory regions
transcription leads to polycistronic RNA (RNA with several coding regions)
question
prokaryote genes
answer
double stranded
supercoiled
circular
antiparallel
supercoiled
circular
antiparallel
question
Prokaryotic DNA
answer
best at 260 nm wavelength
single stranded DNA absorbs more than double stranded DNA (therefore melting of DNA increases the absorbance)
single stranded DNA absorbs more than double stranded DNA (therefore melting of DNA increases the absorbance)
question
DNA Light absorption
answer
single (haploid), supercoiled, double stranded, and circular structure in nucleoid area
E. coli DNA has about 4.7 million bases
E. coli DNA has about 4.7 million bases
question
prokaryotic chromosomes
answer
extrachromosomal elements
may contain information for virulence factors or antibiotic resistant factors
found in all organisms (although uncommon in eukaryotes)
reproduce autonomously, controlling their own replication (either bidirectionally or unidirectionally)
may contain information for virulence factors or antibiotic resistant factors
found in all organisms (although uncommon in eukaryotes)
reproduce autonomously, controlling their own replication (either bidirectionally or unidirectionally)
question
Plasmids
answer
Conjugation
Transformation
Transduction
Transformation
Transduction
question
3 methods of Genetic Exchange
answer
introduce single stranded breaks in prokaryotic DNA that allows supercoiling of the DNA
This allows very long DNA molecules to be packaged into the cell
also used to relieve supercoiled DNA and is required for replication of DNA (and cell division)
This allows very long DNA molecules to be packaged into the cell
also used to relieve supercoiled DNA and is required for replication of DNA (and cell division)
question
Class I topoisomerases
answer
troduce double stranded breaks in prokaryotic DNA that allows supercoiling
question
Class II Topoisomerases
answer
Works in combination with class II topoisomerases (supercoils the DNA after the topoisomerase has acted)
inhibited by Nalidixic Acid, Ciprofloxacin, and novobiocin
inhibited by Nalidixic Acid, Ciprofloxacin, and novobiocin
question
DNA Gyrase
answer
forms domains that are held together by proteins
this prevents entire DNA from uncoiling when one domain is nicked and uncoiled
this prevents entire DNA from uncoiling when one domain is nicked and uncoiled
question
Supercoiled Prokaryotic DNA
answer
derived from bacteria
cut DNA at specific sequences (often palindromic)
allows us to cut DNA into predictable shorter fragments
cuts unmethylated sequence, not methylated
leads to "sticky ends"
cut DNA at specific sequences (often palindromic)
allows us to cut DNA into predictable shorter fragments
cuts unmethylated sequence, not methylated
leads to "sticky ends"
question
Restriction Enzymes
answer
memory bank of nucleic acid sequences from previous bacteriophage encounters
this region of DNA is transcribed when the bacterial cell is attacked again by viral infection
cut CRISPR RNA seeks out invading viral DNA, binds to it, and destroy it with help of Cas proteins
this region of DNA is transcribed when the bacterial cell is attacked again by viral infection
cut CRISPR RNA seeks out invading viral DNA, binds to it, and destroy it with help of Cas proteins
question
CRISPR Interference
answer
DNA Polymerases - attaches nucleotides
Helicase - binds to DNA near replication fork
Primase - makes short RNA starter chains
Ligase - links DNA molecules into single structure
Gyrase (Topoisomerase II) - promotoes supercoiling
Topoisomerase I - relaxes supercoiled DNA
occers in 5' to 3' direction
Helicase - binds to DNA near replication fork
Primase - makes short RNA starter chains
Ligase - links DNA molecules into single structure
Gyrase (Topoisomerase II) - promotoes supercoiling
Topoisomerase I - relaxes supercoiled DNA
occers in 5' to 3' direction
question
Enzymes Necessary for DNA Replication
answer
starts at defined origin of replication
occurs in both strands simultaneously
occurs bidirectionally
takes 40 minutes to complete 1 round
new initiation occurs every 20 minutes
initiation precedes cell division
multiple growing forks may be initiated before septum formation
occurs in both strands simultaneously
occurs bidirectionally
takes 40 minutes to complete 1 round
new initiation occurs every 20 minutes
initiation precedes cell division
multiple growing forks may be initiated before septum formation
question
DNA Replication
answer
synthesis moves toward replication fork
question
Leading Strand
answer
synthesis moves away from replication fork
question
Lagging Strand
answer
stabilizes single strand of DNA during replication
question
single-strand binding proteins
answer
removes RNA primers and then fills gap in DNA
also involved in DNA repair
also involved in DNA repair
question
DNA Polymerase I
answer
proofreads using 3' to 5' exonuclease active
question
DNA Polymerase III
answer
required for RNA polymerase to recognize promotor
is a DNA binding protein that recognizes nucleotide sequences in promotors
important sites at about 10 and about 35 bases upstream of where RNA synthesis begins
is a DNA binding protein that recognizes nucleotide sequences in promotors
important sites at about 10 and about 35 bases upstream of where RNA synthesis begins
question
sigma factor protein
answer
dependent on recognition of specific base sequences by the polymerase at a stem-loop structure in RNA
question
termination of RNA synthesis
answer
multiple translation stop and start sites
contains information for more than one peptide
contains information for more than one peptide
question
polycistronic prokaryotic mRNA
answer
induction
repression
positive control
global control/catabolite repression
quorum sensing
attenuation
two component signal transduction
repression
positive control
global control/catabolite repression
quorum sensing
attenuation
two component signal transduction
question
Regulation at Transcriptional Level
answer
helix-turn-helix motif proteins
zinc finger proteins (binds Zn as Zinc finger binds to DNA
DNA binding proteins necessary for transcriptional control at promoter region
zinc finger proteins (binds Zn as Zinc finger binds to DNA
DNA binding proteins necessary for transcriptional control at promoter region
question
Classes of Protein Domains for DNA Binding Proteins
answer
single operon promotes transcription of multiple genes in same pathway
repression is downregulation and induction is upregulation in this (or other) regions
repression is downregulation and induction is upregulation in this (or other) regions
question
Repression and Induction
answer
repressors bind to operators to prevent transcription
corepressors bind to the repressors themselves, activating it.
corepressors bind to the repressors themselves, activating it.
question
repressor vs corepressor
answer
binds to repressor at allosteric site, and decreases its affinity to the operator
allows transcription
example is allolactose (derivative of lactose produced by beta-galactosidase) in the Lactose operon
allows transcription
example is allolactose (derivative of lactose produced by beta-galactosidase) in the Lactose operon
question
inducer
answer
implemented by activator proteins, which bind to activator-binding sites upstream from promotor
enhance transcription
inducers binds to the activator proteins to promote binding
activator proteins do not bind unless inducer is present
example - maltose is inducer in maltose utilization (a system pertinent in regulons)
enhance transcription
inducers binds to the activator proteins to promote binding
activator proteins do not bind unless inducer is present
example - maltose is inducer in maltose utilization (a system pertinent in regulons)
question
Positive Control
answer
Catabolite Repression (example)- helps cells make most efficient use of different carbon sources
many different genes regulated at once
lac operon is example of catabolite repression
many different genes regulated at once
lac operon is example of catabolite repression
question
Global Regulatory Mechanisms
answer
noticed that when presented with two nutrient sources (glucose and lactose), the organism will suppress formation of enzymes for lactose metabolism and use glucose first
question
Louis Pasteur and Catabolite Repression
answer
requires cAMP to bind to catabolite activator protein (CAP)/cAMP recepter protein (CRP)
CAP/CRP-cAMP complex binds upstream of promotor for lac operon and recruits RNA polymerase
in cells using glucose, cAMP is low, so lac operon is not activated
CAP/CRP-cAMP complex binds upstream of promotor for lac operon and recruits RNA polymerase
in cells using glucose, cAMP is low, so lac operon is not activated
question
Lac Operon and Catabolite Repression
answer
low = when glucose is being used, Enzyme IIA of phosphotransferase system is unphosphorylated
high = when glucose is not being used, Enzyme IIA of phosphotransferase system is phosphorylated
high = when glucose is not being used, Enzyme IIA of phosphotransferase system is phosphorylated
question
Why is cAMP low or high in bacteria using or not using glucose?
answer
genes of a pathway that are spread throughout bacterial chromosome
question
Regulon
answer
membrane-integrated sensor kinase protein
cytoplasmic response regulator protein (activity depends on phosphorylation by sensor kinase protein) - typically a DNA binding protein that acts as a repressor in phosphorylated form
cytoplasmic response regulator protein (activity depends on phosphorylation by sensor kinase protein) - typically a DNA binding protein that acts as a repressor in phosphorylated form
question
Two Component Regulatory Systems
answer
cells detect the accumulation of a released signal and change their behavior when the signal concentration exceeds a threshold
allows cells to survey environment for cells of their own kind (respond to population size)
Once threshold is reached, specific gene expression is triggered
sometimes leads to expression of virulence factors
allows cells to survey environment for cells of their own kind (respond to population size)
Once threshold is reached, specific gene expression is triggered
sometimes leads to expression of virulence factors
question
Quorum Sensing
answer
common quorum sensing inducer
cross bacterial membrane largely through diffusion
bound by LuxR-type regulatory proteins (AHL acyl chain enters hydrophobic acyl-binding pocket)
AHL/LuxR complex binds to DNA promoter region activating several genes in lux operon
cross bacterial membrane largely through diffusion
bound by LuxR-type regulatory proteins (AHL acyl chain enters hydrophobic acyl-binding pocket)
AHL/LuxR complex binds to DNA promoter region activating several genes in lux operon
question
Acyl Homoserine Lactone (AHL)
answer
wide range of activities in different bacteria:
light production
virulence
exopolysaccharide secretion
motility
plasmid transfer
light production
virulence
exopolysaccharide secretion
motility
plasmid transfer
question
lux-like genes
answer
In Staphylococcus:
1. argABCD operon leads to production of ArgD
2. ArgB trims ArgD to autoinducing peptide (AIP) and exports it from cell
3. As cell population increases, AIP concentration increases and binds ArgC, leading to autophosphorylation of ArgC
4. ArgC-P activates transcription activator ArgA by transfer of phosphate group
5. ArgA-P increases transcription of argABCD operon and activates transcription of an RNA that produces virulence proteins
1. argABCD operon leads to production of ArgD
2. ArgB trims ArgD to autoinducing peptide (AIP) and exports it from cell
3. As cell population increases, AIP concentration increases and binds ArgC, leading to autophosphorylation of ArgC
4. ArgC-P activates transcription activator ArgA by transfer of phosphate group
5. ArgA-P increases transcription of argABCD operon and activates transcription of an RNA that produces virulence proteins
question
Quorum Sensing and Virulence Factors
answer
AKA Attenuation
can only occur in prokaryotes with both transcription and translation occurring simultaneously
utilized by operons for amino acid biosynthetic enzymes (transcription does not begin until level of amino acid is low)
ribosomes translate leader mRNA that is enriched in amino acids of that biosynthetic pathway
leader peptide is from first part of polycistronic message
can only occur in prokaryotes with both transcription and translation occurring simultaneously
utilized by operons for amino acid biosynthetic enzymes (transcription does not begin until level of amino acid is low)
ribosomes translate leader mRNA that is enriched in amino acids of that biosynthetic pathway
leader peptide is from first part of polycistronic message
question
Regulation at Translational Level
answer
leader mRNA is fully translated in excess amino acid
mRNA exhibits conformation (stem loop hairpin) that inhibits further transcription - inhibitory stem loop
mRNA exhibits conformation (stem loop hairpin) that inhibits further transcription - inhibitory stem loop
question
Amino Acid Excess
answer
leader mRNA is partially translated
mRNA exhibits different conformation with a different stem loop that does not inhibit further transcription
mRNA exhibits different conformation with a different stem loop that does not inhibit further transcription
question
Amino Acid Starvation
answer
regulation of enzyme activity:
feedback inhibition (most effective for anabolic pathways)
allosteric effectors (non-covalen interactions with enzyme at allosteric site)
feedback inhibition (most effective for anabolic pathways)
allosteric effectors (non-covalen interactions with enzyme at allosteric site)
question
Regulation at post translational level
answer
donor cell is lysed, releasing DNA fragments
DNA fragments enter recipient cell and integrate into DNA
DNA fragments enter recipient cell and integrate into DNA
question
Transformation
answer
cell lysis releases phages with donor genomic DNA
phage infects recipient cell with DNA and it integrates into the recipient cell DNA
phage infects recipient cell with DNA and it integrates into the recipient cell DNA
question
Transduction
answer
plasmid moves from donor to recipient via sex pilus
after plasmid integration, promotion of the transfer of genomic DNA to the recipient begins
after plasmid integration, promotion of the transfer of genomic DNA to the recipient begins
question
Conjugation
answer
important enzyme mediator of homologous recombination
question
RecA protein
answer
state in which cells are capable of taking up free DNA
only cells exhibiting this feature are transformable
only cells exhibiting this feature are transformable
question
Competence
answer
used pneumococcus (streptococcus pneumoniae)
infected mouse with heat killed S cells = live
infected mouse with live S cells = dead
infected mouse with live R cells = live
infected mouse with live R cells + head killed S cells = death
infected mouse with heat killed S cells = live
infected mouse with live S cells = dead
infected mouse with live R cells = live
infected mouse with live R cells + head killed S cells = death
question
Griffith's Experiment demonstrating Transformation
answer
random fragments of DNA from donor are incorporated into virus particle
efficiency of this type of transduction is low
efficiency of this type of transduction is low
question
generalized transduction
answer
viral DNA incorporated into host chromosome
imprecise viral DNA excision from host chromosome so that adjacent genes are also excised
viral infection into another bacterium
efficiency of this type of transduction is high
imprecise viral DNA excision from host chromosome so that adjacent genes are also excised
viral infection into another bacterium
efficiency of this type of transduction is high
question
Specialized transduction
answer
virus whose genome is able to replicate along with that of its host and not cause cell death (called a state of lysogeny)
some cause phenotypic changes in the bacteria they infect even without transducing bacterial genes
example is lambda phage
some cause phenotypic changes in the bacteria they infect even without transducing bacterial genes
example is lambda phage
question
temperate virus
answer
aka prophage
genome of a temperate virus when it is replicating within the host chromosome
genome of a temperate virus when it is replicating within the host chromosome
question
Provirus
answer
bacterium that contains a prophage
question
lysogen
answer
series of steps after virus infection that leads to virus replication and destruction of host cell
viral genes confer new properties on the cell (phage conversion)
viral genes confer new properties on the cell (phage conversion)
question
Lysogenic Pathway
answer
series of steps after virus infection that leads to virus replication and destruction of host cell
excision of phage DNA from host DNA leads to normal phage production without host DNA excision
excision of phage DNA from host DNA leads to normal phage production without host DNA excision
question
Lytic Pathway
answer
virus genome is incorporated into the bacterial DNA at the same location each time
only a few of the same bacterial genes are transduced each time there is a rare imprecise excision
only a few of the same bacterial genes are transduced each time there is a rare imprecise excision
question
Specialized Transduction and Temperate Phages
answer
toxin production by pathogenic bacteria such as Corynebacterium Diphtheriae
surface polysaccharide structure in Salmonella anatum
surface polysaccharide structure in Salmonella anatum
question
examples of phage conversion
answer
genes carried by certain plasmids (F plasmid of E. coli) control conjugation - called the tra region
the process involves transferring plasmid to recipient cell
involves plasmid replication by a rolling circle mechanism
the process involves transferring plasmid to recipient cell
involves plasmid replication by a rolling circle mechanism
question
Plasmids and Conjugation
answer
beginning at OriT point, one strand rolls off the existing strand
single strand is transferred to the recipient
complementary strand is immediately replicated in both donor and recipient
single strand is transferred to the recipient
complementary strand is immediately replicated in both donor and recipient
question
rolling circle mechanism
answer
plasmid genes may confer resistance to antibiotics, production of toxins, and the capacity to metabolize unusual substances, such as pesticides and industrial solvents
some antibiotic resistance conferred by R plasmids:
some antibiotic resistance conferred by R plasmids:
question
Plasmids and Resistance
answer
may confer resistance to as many as 5 different antibiotics at once
can be rapidly disseminated through bacterial population through conjugation.
can be rapidly disseminated through bacterial population through conjugation.
question
R Plasmids
answer
1. Vancomycin resistant enterococcus (VRE) contains plasmids with multiple resistance and virulence factors
2. MRSA may aquire VRE plasmid (e-plasmid) by transformation or conjugatino during co-infection
3. transposon in e-plasmid containing vancomycin resistance gene jumps to multiple antibiotic resistance plasmid in MRSA
4. new plasmid spread to other staphylococcus aureus bacteria by conjugation
2. MRSA may aquire VRE plasmid (e-plasmid) by transformation or conjugatino during co-infection
3. transposon in e-plasmid containing vancomycin resistance gene jumps to multiple antibiotic resistance plasmid in MRSA
4. new plasmid spread to other staphylococcus aureus bacteria by conjugation
question
Evolution of Methicillin and Vancomycin-resistant Staphylococcus Aureus (MRSA and MVRSA)
answer
involved in conjugation between bacteria of same species
some viruses use these as receptors to infect bacteria
requires cell to cell contact
referred to as bacterial mating
donor, but not recipient, possesses this, and it can transfer plasmid or plasmid-chromosome
occurs during DNA replication and only one strand of DNA transfers from donor to recipient
some viruses use these as receptors to infect bacteria
requires cell to cell contact
referred to as bacterial mating
donor, but not recipient, possesses this, and it can transfer plasmid or plasmid-chromosome
occurs during DNA replication and only one strand of DNA transfers from donor to recipient
question
Pilus
answer
contains F-plasmid
question
F+ cell
answer
does not contain F-plasmid
question
F- cell
answer
initiate gen transfer by altering cell surface to allow contact between F+ and F- cells
plasmid gene codes for production of sex pilus that initiates pair formation
conjugation bridge is formed through which DNA transfers
DNA transfer is accompanied by its replication
recipient can now act as a plasmid donor in other conjugations
plasmid gene codes for production of sex pilus that initiates pair formation
conjugation bridge is formed through which DNA transfers
DNA transfer is accompanied by its replication
recipient can now act as a plasmid donor in other conjugations
question
Conjugative Plasmids
answer
High frequency recombination cells
question
Hfr Cells
answer
donor cell mobilizes chromosome for transfer to recipient
requires F-plasmid integration into host chromosome to produce Hfr phenotype
transfer of host chromosome along with integrated F-plasmid occurs with varying degrees of completion
variety in host chromosome plasmid transfer allowed for first mapping of bacterial chromosome
requires F-plasmid integration into host chromosome to produce Hfr phenotype
transfer of host chromosome along with integrated F-plasmid occurs with varying degrees of completion
variety in host chromosome plasmid transfer allowed for first mapping of bacterial chromosome
question
formation of Hfr strains and chromosome mobilization
answer
integrates into chromosome at specific sites (special conjugative plasmid)
mobilizes host chromosome starting at same spot
allows for high frequency of chromosomal transfer or recombination (Hfr)
prevents donor from being recipient
imprecise excision leads to F' plasmid with a piece of host DNA or just the F plasmid
mobilizes host chromosome starting at same spot
allows for high frequency of chromosomal transfer or recombination (Hfr)
prevents donor from being recipient
imprecise excision leads to F' plasmid with a piece of host DNA or just the F plasmid
question
F-Plasmid
answer
regions of DNA sequence homology between chromosomal and F plasmid DNA
question
Insertion Sites (IS)
answer
closest host genes get peeled off first (within minutes), while the farthest host genes could transfer (but will take a long time - up to 100 minutes)
question
Peeling off of Chromosomal DNA with F-plasmid
answer
clone foreign DNA into plasmid vectors with a lacZ beta-galactosidase gene and an antibiotic resistance gene
1. vector and foreign DNA digested by same restriction enzyme
2. insertion of foreign DNA into lacZ gene inactivates beta-galactosidase gene
3. vector is ligated to foreign DNA with bacteriophage T4 DNA ligase
4. recombinant vectors are transformed into E. coli cells
5. recombinant E. coli plated onto agar containing antibiotic, and induce of the lac operon, and a chromophoric substance (turns cells without insert blue)
6. look for cells that are white, because they have the plasmid containing the insert
1. vector and foreign DNA digested by same restriction enzyme
2. insertion of foreign DNA into lacZ gene inactivates beta-galactosidase gene
3. vector is ligated to foreign DNA with bacteriophage T4 DNA ligase
4. recombinant vectors are transformed into E. coli cells
5. recombinant E. coli plated onto agar containing antibiotic, and induce of the lac operon, and a chromophoric substance (turns cells without insert blue)
6. look for cells that are white, because they have the plasmid containing the insert
question
Gene Cloning
answer
use of chemical agents on living tissue to inhibit or eliminate microbes
no sporicidal action
no sporicidal action
question
antisepsis
answer
use of physical procedures or chemical agents to destroy most microbial forms
bacterial spores and other relatively resistant organisms may remain
bacterial spores and other relatively resistant organisms may remain
question
disinfection
answer
chemical agent capable of killing microbes
includes virucide, bactericide, sporicide, tuberculocide, and fungicide
includes virucide, bactericide, sporicide, tuberculocide, and fungicide
question
germicide
answer
germicide that kills all microbial pathogens except large numbers of spores
used for items for invasive procedures that cannot withstand sterilization procedures
most effective if cleaning the surface to remove organic matter precedes treatment
moist heat, glutaraldehyde, hydrogen peroxide, peracetic acid, and chlorine compounds
used for items for invasive procedures that cannot withstand sterilization procedures
most effective if cleaning the surface to remove organic matter precedes treatment
moist heat, glutaraldehyde, hydrogen peroxide, peracetic acid, and chlorine compounds
question
high-level disinfectant
answer
germicide that kills all microbial pathogens except bacterial endospores
used for surfaces of instruments where contamination with spores and highly resilient organisms is unlikely
used for semicritical instruments
alcohols, iodophor compounds, phenolic compounds
used for surfaces of instruments where contamination with spores and highly resilient organisms is unlikely
used for semicritical instruments
alcohols, iodophor compounds, phenolic compounds
question
intermediate-level disinfectant
answer
germicide that kills most vegetative bacteria and lipid-envoloped and medium-size virus
used for non-critical instruments and devices such as blood pressure cuffs, EKG electrodes, and stethoscopes
do not penetrate through mucosal surfaces or into sterile tissues
quaternary ammonium compounds
used for non-critical instruments and devices such as blood pressure cuffs, EKG electrodes, and stethoscopes
do not penetrate through mucosal surfaces or into sterile tissues
quaternary ammonium compounds
question
low-level disinfectant
answer
use of physical procedures or chemical agents to destroy all microbial forms, including spores
question
sterilization
answer
steam under pressure - 121 -132C for various time intervals
filtration - 0.22-0.45 micron pore size; HEPA filters
ultraviolet radiation - variable exposure at 254nm wavelength
ionizing radiation - variable exposure to microwave or gamma radiation
filtration - 0.22-0.45 micron pore size; HEPA filters
ultraviolet radiation - variable exposure at 254nm wavelength
ionizing radiation - variable exposure to microwave or gamma radiation
question
Physical sterilants
answer
Ethylene Oxide - 450-1200 mg/L at 29-65C for 2-5hr
Hydrogen Peroxide Vapor - 30% at 55-60C
Plasma Gas - highly ionized hydrogen peroxide gas
Hydrogen Peroxide Vapor - 30% at 55-60C
Plasma Gas - highly ionized hydrogen peroxide gas
question
Gas Vapor Sterilants
answer
Peracetic Acid - 0.2%
Glutaraldehyde - 2%
Glutaraldehyde - 2%
question
Chemical Sterilants
answer
steam under pressure of 1.1 kg/cm2 (15lb/in2) - yields temperature of 121C
time to achieve sterilization of endospore containing material at this temperature is 15 minutes (bulky or large liquids require longer)
drop in temperature 1.7C increases necessary exposure time by 48% (proper temp is important)
time to achieve sterilization of endospore containing material at this temperature is 15 minutes (bulky or large liquids require longer)
drop in temperature 1.7C increases necessary exposure time by 48% (proper temp is important)
question
Autoclaves
answer
temperature must reach 160C
question
Dry Heat Sterilization
answer
used as a spore test
placed in autoclave to test the effectiveness of sterilization
at end of autoclave cycle, spores are removed and incubated at 37C.
if no growth, the autoclave is working correctly
placed in autoclave to test the effectiveness of sterilization
at end of autoclave cycle, spores are removed and incubated at 37C.
if no growth, the autoclave is working correctly
question
Commercial Preparations of Bacillus Stearothermophilus
answer
between 220 and 300 nm wavelength is absorbed by DNA and causes mutations or other serious effects
useful for surfaces and air, and is widely used to decontaminate and disinfect work surfaces of laboratory laminar flow hoods equipped with germicidal UV light
disinfects air circulating in hospital and food prep rooms
poor penetrating power (doesn't work on bulk objects
useful for surfaces and air, and is widely used to decontaminate and disinfect work surfaces of laboratory laminar flow hoods equipped with germicidal UV light
disinfects air circulating in hospital and food prep rooms
poor penetrating power (doesn't work on bulk objects
question
Ultraviolet Radiation
answer
electromagnetic radiation that produces ions and other reactive molecular species
generates high energy electrons, hydroxyl radicals, and hydride radicals, which can damage macromolecules and kill irradiated cells
nuclides produce X-rays or gamma rays that have energy and penetrating power to kill microorganisms in bulk items
generates high energy electrons, hydroxyl radicals, and hydride radicals, which can damage macromolecules and kill irradiated cells
nuclides produce X-rays or gamma rays that have energy and penetrating power to kill microorganisms in bulk items
question
Ionizing Radiation
answer
used to sterilize temperature or pressure sensitive items
sporicidal activity through alkylation of terminal hydroxyl, carboxyl, amino, and sulfahydryl groups
treatment is generally 4 hours and items must be aerated for another 12 hours
highly efficient, but strict regulations limit its use
flammable, explosive, and carcinogenic to lab animals
avoided if acceptable alternative are available
sporicidal activity through alkylation of terminal hydroxyl, carboxyl, amino, and sulfahydryl groups
treatment is generally 4 hours and items must be aerated for another 12 hours
highly efficient, but strict regulations limit its use
flammable, explosive, and carcinogenic to lab animals
avoided if acceptable alternative are available
question
Ethylene Oxide Gas
answer
effective because of oxidizing nature of gas
used for sterilization of instruments
used for sterilization of instruments
question
Hydrogen Peroxide Vapors
answer
variation of hydrogen peroxide vapors where free radicals are produced with either microwave or radio-frequency energy
replaced many of the applications of ethylene oxide
cannot be used with materials that absorb hydrogen peroxide or react with it
replaced many of the applications of ethylene oxide
cannot be used with materials that absorb hydrogen peroxide or react with it
question
Plasma Gas
answer
nature of item to be disinfected
number and resilience of contaminating organisms
amount of organic material present (inactivates disinfectant)
type and concentration of disinfectant
duration and temperature of exposure
number and resilience of contaminating organisms
amount of organic material present (inactivates disinfectant)
type and concentration of disinfectant
duration and temperature of exposure
question
Effectiveness of Disinfectants Depend on
answer
moist heat - 75-100C for 30min (high-level)
question
Head Method of Disinfectant
answer
Glutaraldehyde - 2-3.2% (high-level)
Hydrogen Peroxide - 3-25% (high-level)
Chlorine Compounds - 100-1000 ppm of free chlorine (high-level)
Alcohol (ethyl, isopropyl) - 70-95% (intermediate-level)
Phenolic Compounds - 0.4-5% (intermediate/low-level)
Iodophor Compounds - 30-50 ppm of free iodine/L (intermediate-level)
Quaternary Compounds - 0.4-1.6% (low-level)
Hydrogen Peroxide - 3-25% (high-level)
Chlorine Compounds - 100-1000 ppm of free chlorine (high-level)
Alcohol (ethyl, isopropyl) - 70-95% (intermediate-level)
Phenolic Compounds - 0.4-5% (intermediate/low-level)
Iodophor Compounds - 30-50 ppm of free iodine/L (intermediate-level)
Quaternary Compounds - 0.4-1.6% (low-level)
question
Liquid Methods of Disinfectant
answer
sterilizing equipment using boiling water is inefficient because on 100C is reached and spores still survive
boiling does kill vegetative organisms by denaturing microbial proteins
boiling does kill vegetative organisms by denaturing microbial proteins
question
Moist Heat
answer
exert their effect through alkylation
formaldehyde (rarely used in health care settings) and glutaraldehyde (less toxic than formaldehyde) are best-known
exposure of skin or mucous membrane to formaldehyde can be toxic, and vapors may be carcinogenic
formaldehyde (rarely used in health care settings) and glutaraldehyde (less toxic than formaldehyde) are best-known
exposure of skin or mucous membrane to formaldehyde can be toxic, and vapors may be carcinogenic
question
Aldehydes
answer
examples = ozone, peracetic acid, and hydrogen peroxide
hydrogen peroxide effectively kills most bacteria at 3-6% and kills spores at 10-25%
active oxidant form of hydrogen peroxide is the free hyroxyl radical formed by decomposition of hydrogen peroxide
hydrogen peroxide used to disinfect plastic implants, contact lenses, and surgical prostheses
hydrogen peroxide effectively kills most bacteria at 3-6% and kills spores at 10-25%
active oxidant form of hydrogen peroxide is the free hyroxyl radical formed by decomposition of hydrogen peroxide
hydrogen peroxide used to disinfect plastic implants, contact lenses, and surgical prostheses
question
Oxidizing Agents
answer
compounds containing iodine or chlorine (used extensively)
iodine compounds most effective
iodine compounds most effective
question
Halogens
answer
highly reactive element that precipitates proteins and oxidizes enzymes
microbicidal against virtually all organisms, including spore-forming bacteria and mycobacteria
Povidone iodine is used most commonly - relatively stable and nontoxic to tissues and metal surfaces
microbicidal against virtually all organisms, including spore-forming bacteria and mycobacteria
Povidone iodine is used most commonly - relatively stable and nontoxic to tissues and metal surfaces
question
iodine compounds
answer
used extensively and aqueous solutions are rapidly bactericidal
can exert its effect by irreversible oxidation of -SH groups of enzymes
hypochlorites interact with cytoplasmic components to form toxic N-chloro compounds (interfere with metabolism)
demonstrate good germicidal activity, although spore-forming organisms are 10-1000 times more resistant than vegetative bacteria
can exert its effect by irreversible oxidation of -SH groups of enzymes
hypochlorites interact with cytoplasmic components to form toxic N-chloro compounds (interfere with metabolism)
demonstrate good germicidal activity, although spore-forming organisms are 10-1000 times more resistant than vegetative bacteria
question
chlorine compounds
answer
elemental Chlorine (Cl2) - strong oxidizing agent
hypochlorous acid (HOCl)
Hypochlorite ion (OCl2)
hypochlorous acid (HOCl)
Hypochlorite ion (OCl2)
question
3 forms of Chlorine in Water
answer
rarely used as disinfectants
not sporicidal at room temperature
believed to act by disrupting lipid-containing membranes (leakage of cell contents)
bisphenols = two phenol compounds linked together
halogenated bisphenol example - hexachlorophene
not sporicidal at room temperature
believed to act by disrupting lipid-containing membranes (leakage of cell contents)
bisphenols = two phenol compounds linked together
halogenated bisphenol example - hexachlorophene
question
Phenolic Compounds
answer
two phenol compounds linked together
halogenated bisphenol example - hexachlorophene; an antiseptic with activity against gram positive bacteria
halogenated bisphenol example - hexachlorophene; an antiseptic with activity against gram positive bacteria
question
Bisphenols
answer
consists of four organic groups covalently linked to nitrogen
examples - benzalkonium chloride and cetylpyridinium chloride
denature cell membranes to release intracellular components
examples - benzalkonium chloride and cetylpyridinium chloride
denature cell membranes to release intracellular components
question
Quaternary Ammonium Compounds
answer
pseudomonas
Mycobacterium
trichophyton (fungi)
many viruses and all bacterial spores
Mycobacterium
trichophyton (fungi)
many viruses and all bacterial spores
question
Bacteria Resistant to Quaternary Ammonium Compounds
answer
germicidal activity increases with increasing chain length (maximum 5-8 carbons)
ethanol and isopropanol are most common
rapidly bactericidal against vegetative bacteria, mycobacteria, some fungi, and lipid-containing viruses
activity greater in presence of water (ie 70% is more active than 95%)
common disinfectant of skin surfaces and is extremely effective for this purpose when treated with iodophor afterward
used to disinfect thermometers
ethanol and isopropanol are most common
rapidly bactericidal against vegetative bacteria, mycobacteria, some fungi, and lipid-containing viruses
activity greater in presence of water (ie 70% is more active than 95%)
common disinfectant of skin surfaces and is extremely effective for this purpose when treated with iodophor afterward
used to disinfect thermometers
question
Alcohols
answer
alcohol (ethyl, isopropyl) - 70-90%
iodophors - 1-2mg of free iodine/L; 1-2% available iodine
chlorhexidine - 0.5-4%
parachlorometaxylenol - 0.5-3.75%
Triclosan - 0.3-2%
iodophors - 1-2mg of free iodine/L; 1-2% available iodine
chlorhexidine - 0.5-4%
parachlorometaxylenol - 0.5-3.75%
Triclosan - 0.3-2%
question
Antiseptic Agents
answer
excellent activity against all groups of organisms except spores
nontoxic, but can dry skin surface because of removal of lipids
no residual activity and is inactivated by organic matter
surface of skin should be cleaned before alcohol is applied
nontoxic, but can dry skin surface because of removal of lipids
no residual activity and is inactivated by organic matter
surface of skin should be cleaned before alcohol is applied
question
Alcohols (as antiseptic)
answer
excellent skin antiseptic agent
range of activity similar to alcohols (slightly more toxic)
limited residual activity, inactivated by organic matter
frequently used with alcohols
range of activity similar to alcohols (slightly more toxic)
limited residual activity, inactivated by organic matter
frequently used with alcohols
question
Iodophors
answer
broad antimicrobial activity
kills at slower rate than alcohol
activity persists
effectiveness decreased by organic material and high pH levels
kills at slower rate than alcohol
activity persists
effectiveness decreased by organic material and high pH levels
question
Chlorhexidine
answer
limited primarily to gram-positive bacteria
non-toxic and has residual activity
used in hand washing
non-toxic and has residual activity
used in hand washing
question
Parachlorometaxylenol
answer
active against bacteria but not many other organisms
common in deodorant soaps and some toothpastes
may cause development of antibiotic resistant strains of bacteria
use is being phased out
common in deodorant soaps and some toothpastes
may cause development of antibiotic resistant strains of bacteria
use is being phased out
question
Triclosan
answer
heat treatment of milk or other liquids to reduce microbe content, but does not kill all organisms (so not sterilized)
invented by louis pasteur
first used to control spoilage of wine
all known pathogenic bacteria transmitted in milk are killed
liquid brought to 71C for 15 seconds, then rapidly cooled (flash pasteurization)
milk can be pasteurized in large vats at 63-66C for 30 min
invented by louis pasteur
first used to control spoilage of wine
all known pathogenic bacteria transmitted in milk are killed
liquid brought to 71C for 15 seconds, then rapidly cooled (flash pasteurization)
milk can be pasteurized in large vats at 63-66C for 30 min
question
Pasteurization
answer
range of activity of an antimicrobial against bacteria
question
antibacterial spectrum
answer
inhibits variety of gram positive and negative bacteria
question
broad-spectrum antibacterial drug
answer
active against limited variety of bacteria
question
narrow-spectrum antibacterial drug
answer
inhibits growth of bacteria, but does not kill
question
bacteriostatic antibiotic
answer
kills bacteria
question
bactericidal antibiotic
answer
lowest antibiotic concentration that inhibits growth of the bacteria
question
minimum inhibitory concentration (MIC)
answer
lowest antibiotic concentration that kills 99.9% of population
question
minimum bactericidal concentration (MBC)
answer
combinations of antibiotics that:
1. broaden antibacterial spectrum for empirical therapy
2. prevent emergence of resistant organisms during therapy
3. achieve a synergistic killing
1. broaden antibacterial spectrum for empirical therapy
2. prevent emergence of resistant organisms during therapy
3. achieve a synergistic killing
question
antibiotic combinations
answer
combinations of two antibiotics that have enhanced antibiotic activity when tested together compared with separately
question
antibiotic synergism
answer
combination of antibiotics in which the activity of one antibiotic interferes with activity of another
question
antibiotic antagonism
answer
enzyme that hydrolyzes the beta-lactam ring in the beta-lactam class of antibiotics, thus inactivating it
question
beta-lactamase
answer
penicillins
cephalosporins
cephamycins
carbapenems
monobactams
cephalosporins
cephamycins
carbapenems
monobactams
question
Drugs that bind PBPs and enzymes responsible for peptidoglycan synthesis
answer
beta-lactam/lactamase inhibitors
question
drugs that bind beta-lactamases
answer
most common mechanism of antibiotic activity
most are beta-lactam antibiotics (share a common beta-lactam ring structure)
target penicillin-binding proteins (PBPs) that are responsible for peptidoglycan cross-links
disruption of peptidoglycan synthesis triggers autolysins that degrade existing cell wall (killing bacteria)
most are beta-lactam antibiotics (share a common beta-lactam ring structure)
target penicillin-binding proteins (PBPs) that are responsible for peptidoglycan cross-links
disruption of peptidoglycan synthesis triggers autolysins that degrade existing cell wall (killing bacteria)
question
Inhibition of Cell Wall Synthesis
answer
1. decreased concentration of antibiotic at cell wall target site
2. decreased binding of the antibiotic to the PBP
3. hydrolysis of antibiotic by bacterial enzymes, beta-lactamases
2. decreased binding of the antibiotic to the PBP
3. hydrolysis of antibiotic by bacterial enzymes, beta-lactamases
question
3 Ways Bacteria Can become resistant to beta-lactam antibiotics
answer
highly effective with low toxicity
basic compound obtained from culture of mold penicillium chrysogenum - 6-aminopenicillanic acid
basic compound obtained from culture of mold penicillium chrysogenum - 6-aminopenicillanic acid
question
Penicillins
answer
if mold grown by fermentation, large amounts of 6-aminopenicillanic acid are produced
question
penicillium chrysogenum
answer
increases resistance of stomach acids
increases absorption in gut
increases resistance to penicillinase
increases spectrum of activity that includes gram-negative bacteria
increases absorption in gut
increases resistance to penicillinase
increases spectrum of activity that includes gram-negative bacteria
question
6-aminopenicillanic acid
answer
inactivated by gastric acid; thus it is used mainly as an intravenous drug
question
Penicillin G
answer
more resistant to acid and is preferred oral form for treatment of susceptible bacteria
question
Penicillin V
answer
beta-lactam antibiotics originally isolated from the mold Cephalosporium
wider antibacterial spectrum than penicillins
resistant to many beta-lactamases
wider antibacterial spectrum than penicillins
resistant to many beta-lactamases
question
Cephalosporins
answer
closely related to cephalosporins, except they contain oxygen in place of sulfur in the dihydrothiazine ring
this makes them more stable to beta-lactamase hydrolysis
wider antibacterial spectrum than penicillins
resistant to many beta-lactamases
this makes them more stable to beta-lactamase hydrolysis
wider antibacterial spectrum than penicillins
resistant to many beta-lactamases
question
Cephamycins
answer
clavulanate
question
number 1 beta-lactamase inhibitor
answer
benzylpenicillin (penicillin G)
phenoxymethyl penicillin (penicillin V)
active against all beta-hemolytic streptococci and most other species, meningococci and most gram-positive anaerobes
limited activity against staphylococci
poor activity against aerobic and anaerobic gram negative rods
phenoxymethyl penicillin (penicillin V)
active against all beta-hemolytic streptococci and most other species, meningococci and most gram-positive anaerobes
limited activity against staphylococci
poor activity against aerobic and anaerobic gram negative rods
question
natural penicillins
answer
methicillin, nafcillin, oxacillin, cloxacillin, dicloxacillin
similar to natural penicillins except enhanced activity against staphylococci
similar to natural penicillins except enhanced activity against staphylococci
question
Penicillinase-resistant penicillins
answer
ampicillin and amoxicillin
activity against gram-positive cocci and some gram-negative rods
equivalent to natural penicillins
activity against gram-positive cocci and some gram-negative rods
equivalent to natural penicillins
question
broad-spectrum penicillins
answer
ampicillin-sulbactam
amoxicillin-clavulanate
ticarcillin-clavulanate
piperacillin-tazobactam (most active)
activity similar to natural beta-lactams, plus improved activities against beta-lactamase-producing staphylococci and selected gram-negative rods
not all beta-lactamases are inhibited
amoxicillin-clavulanate
ticarcillin-clavulanate
piperacillin-tazobactam (most active)
activity similar to natural beta-lactams, plus improved activities against beta-lactamase-producing staphylococci and selected gram-negative rods
not all beta-lactamases are inhibited
question
beta-lactam and beta-lactamase inhibitors
answer
vancomycin, daptomycin, bacitracin
antimicrobial agents: isoniazid, ethambutol, cycloserine, and ethionamide
antimicrobial agents: isoniazid, ethambutol, cycloserine, and ethionamide
question
Other Drugs than Penicillins that interfere with bacterial cell wall synthesis
answer
inhibits synthesis of mycolic acid
question
isoniazid
answer
disrupts arabinogalactan synthesis
question
ethambutol
answer
analog of D-alanine
inhibits D-alanine-D-alanine synthetase and alanine racemase
inhibits D-alanine-D-alanine synthetase and alanine racemase
question
cycloserine
answer
disruption of mycolic acids
question
ethionamide
answer
intrinsic: leuconostoc, lactobacillus, pediococcus, erysipelothrix, enterococcus gallinarum, and enterococcus casseliflavus
aquired: enterococcus faecium and enterococcus facecalis
aquired: enterococcus faecium and enterococcus facecalis
question
bacteria resistant to vancomycin
answer
isolated from bacillus licheniformis
a mixture of polypeptides
used typically in creams, ointments and sprays for skin infections caused by gram positive bacteria (Staphylococcus and group A Streptococcus)
gram-negative bacteria are resistant
interferes with bactoprenol carrier of peptidoglycan precursors
resistance caused by failure of antibiotic to penetrate the bacterial cell
a mixture of polypeptides
used typically in creams, ointments and sprays for skin infections caused by gram positive bacteria (Staphylococcus and group A Streptococcus)
gram-negative bacteria are resistant
interferes with bactoprenol carrier of peptidoglycan precursors
resistance caused by failure of antibiotic to penetrate the bacterial cell
question
Bacitracin
answer
used for treatment of mycobacterial infections
bactericidal against actively replicating mycobacteria
exact mechanism unknown
affects mycolic acid synthesis
bactericidal against actively replicating mycobacteria
exact mechanism unknown
affects mycolic acid synthesis
question
isoniazid, ethionamide, ethambutol, and cycloserine
answer
quinolones - binds alpha subunit of DNA gyrase
rifampin - prevents transcription by binding RNA polymerase
rifabutin - prevents transcription by binding RNA polymerase
metronidazole - disrupts bacteria DNA (cytotoxic compound)
antimetabolite
sulfonamides - inhibits dihydropteroate synthase and disrupts folic acid synthesis
dapsone - inhibits dihydropteroate synthase
trimethoprim - inhibits dihydropteroate reductase and disrupts folic acid synthesis
rifampin - prevents transcription by binding RNA polymerase
rifabutin - prevents transcription by binding RNA polymerase
metronidazole - disrupts bacteria DNA (cytotoxic compound)
antimetabolite
sulfonamides - inhibits dihydropteroate synthase and disrupts folic acid synthesis
dapsone - inhibits dihydropteroate synthase
trimethoprim - inhibits dihydropteroate reductase and disrupts folic acid synthesis
question
Drugs that inhibit Nucleic Acid Synthesis
answer
widely used class of antibiotics
synthetics that inhibit bacterial DNA topoisomerase II (gyrase) or topoisomerase type IV, required for DNA replication, recombination, and repair
DNA gyrase-A subunit is primary target in gram negative bacteria
topoisomerase type IV is primary target in gram positive bacteria
excellent activity against gram positive and negative bacteria, but resistance can develop rapidly
synthetics that inhibit bacterial DNA topoisomerase II (gyrase) or topoisomerase type IV, required for DNA replication, recombination, and repair
DNA gyrase-A subunit is primary target in gram negative bacteria
topoisomerase type IV is primary target in gram positive bacteria
excellent activity against gram positive and negative bacteria, but resistance can develop rapidly
question
Quinolones
answer
nalidixic acid, ciprofloxacin, levofloxacin, and moxifloxacin
newer ones like moxifloxacin have significant activity against gram positive bacteria
newer ones like moxifloxacin have significant activity against gram positive bacteria
question
examples of quinolones
answer
semisynthetic derivative of rifamycin B produced by streptomyces mediterranei
binds to RNA polymerase and inhibits RNA synthesis
bactericidal for mycobacterium tuberculosis
very active against aerobic gram positive cocci, including staphylococci and streptococci
resistance can develop rapidly
gram-negative bacteria intrinsically resistant to rifampin (because of decreased uptake)
binds to RNA polymerase and inhibits RNA synthesis
bactericidal for mycobacterium tuberculosis
very active against aerobic gram positive cocci, including staphylococci and streptococci
resistance can develop rapidly
gram-negative bacteria intrinsically resistant to rifampin (because of decreased uptake)
question
Rifampin and Rifabutin
answer
aminoglycosides - produce premature release of peptide chains from 30S ribosome
tetracyclines - prevent polypeptide elongation at 30S ribosome
glycylcyclines - bind to 30S ribosome and prevent initiation of protein synthesis
oxazolidinone - prevents initiation of protein synthesis at 50S ribosome
macrolides
ketolides
clindamycin
streptogramins
tetracyclines - prevent polypeptide elongation at 30S ribosome
glycylcyclines - bind to 30S ribosome and prevent initiation of protein synthesis
oxazolidinone - prevents initiation of protein synthesis at 50S ribosome
macrolides
ketolides
clindamycin
streptogramins
question
Drugs that inhibit Protein Synthesis
answer
amino sugars linked through glycosidic bonds to an aminocyclitol ring.
streptomycin, neomycin, kanamycin, and tobramycin originally isolated from streptomyces species
gentamicin and sisomicin isolated from micromonospora species
pass through outer membrane, cell wall, and cytoplasmic membrane to cytoplasm, to inhibit protein synthesis by irreversibly binding to 30S ribosomal proteins
results in production of aberrant proteins and interruption of protein synthesis
streptomycin, neomycin, kanamycin, and tobramycin originally isolated from streptomyces species
gentamicin and sisomicin isolated from micromonospora species
pass through outer membrane, cell wall, and cytoplasmic membrane to cytoplasm, to inhibit protein synthesis by irreversibly binding to 30S ribosomal proteins
results in production of aberrant proteins and interruption of protein synthesis
question
aminoglycosides
answer
broad-spectrum, bacteriostatic antibiotics
bind irreversibly to 30S ribosomal subunits
tetracycline, doxycycline, minocycline are effective in treatment of infections causes by chlamydia, mycoplasma, and rickettsia species and other gram-positive and gram-negative bacteria
most common resistance is due to a variety of genes that control active efflux of tetracyclines from the cell
bind irreversibly to 30S ribosomal subunits
tetracycline, doxycycline, minocycline are effective in treatment of infections causes by chlamydia, mycoplasma, and rickettsia species and other gram-positive and gram-negative bacteria
most common resistance is due to a variety of genes that control active efflux of tetracyclines from the cell
question
tetracyclines
answer
erythromycin is derived from streptomyces erythreus
basic structure is macrocyclic lactone ring bound to two sugars, desosamine and cladinose
modification led to azithromycin, clarithromycin, and roxithromycin
binds to 23S rRNA of 50S subunit to block elongation
bacteriostatic and broad-spectrum
used to treat pulmonary infections caused by mycoplasma, legionella, and chlamydia species
azithromycin and clarithromycin have been used to treat infections caused by mycobacteria
basic structure is macrocyclic lactone ring bound to two sugars, desosamine and cladinose
modification led to azithromycin, clarithromycin, and roxithromycin
binds to 23S rRNA of 50S subunit to block elongation
bacteriostatic and broad-spectrum
used to treat pulmonary infections caused by mycoplasma, legionella, and chlamydia species
azithromycin and clarithromycin have been used to treat infections caused by mycobacteria
question
macrolides
answer
broad antibacterial spectrum similar to tetracycline
not commonly used in US due to interference with protein synthesis in human bone marrow cells
can produce blood dyscrasias, such as aplastic anemia
exerts bacteriostatic effect by binding reversibly to the peptidyl transferase component of 50S ribosomal subunit (blocking elongation)
not commonly used in US due to interference with protein synthesis in human bone marrow cells
can produce blood dyscrasias, such as aplastic anemia
exerts bacteriostatic effect by binding reversibly to the peptidyl transferase component of 50S ribosomal subunit (blocking elongation)
question
chloramphenicol
answer
Over 80 phyla of bacteria are known to exist based on 16s rRNA sequence information
90% of all characterized species are in phyla: proteobacteria, actinobacteria, firmicutes, and bacteroidetes
few than half of all species have been characterized
90% of all characterized species are in phyla: proteobacteria, actinobacteria, firmicutes, and bacteroidetes
few than half of all species have been characterized
question
Bacterial Phylogeny
answer
a diverse phyla of gram negative bacteria with several classes
some of the classes live in or on humans, especially gamma proteobacteria
some of the classes live in or on humans, especially gamma proteobacteria
question
proteobacteria
answer
contain the lactic acid producing bacteria
are fermentative and do not produce energy through oxidative phosphorylation
catalase negative and contain streptococcus species
aerotolerant anaerobes
are fermentative and do not produce energy through oxidative phosphorylation
catalase negative and contain streptococcus species
aerotolerant anaerobes
question
Firmicutes
answer
obligate anaerobes
non-spore forming and thus some are part of anaerobic environments of the human body
includes porphyromonas gingivalis
non-spore forming and thus some are part of anaerobic environments of the human body
includes porphyromonas gingivalis
question
Bacteroidetes
answer
begins when babies are "painted" as they leave the birth canal (helps ensure that it's microbiome is like its mother's)
breast milk contains nutrients not only for the baby, but also for the microbiome
breast milk contains nutrients not only for the baby, but also for the microbiome
question
Human Microbiome
answer
arbitrarily defined as the species that are present at a specific site in 95% or more of individuals
question
core microbiome
answer
microbial species that contribute to the unique diversity of individuals at specific body sites
question
secondary microbiome
answer
disruption of the normal microbiome that can lead to disease by elimination of microbiome organisms allowing growth of inappropriate bacteria
question
dysbiosis
answer
two organisms live together and only one benefits
question
commensals
answer
two organisms live together and both benefit
question
mutuals
answer
community of microbes that live in and on an individual; can vary widely
aka normal flora
aka normal flora
question
microbiota
answer
1. saturation of colonization sites and consumption of nutrients limits pathogen access
2. microbiota prime innate immunity by stimulating mucin production, IgA, and antimicrobial peptides (AMPs)
3. microbiota stimulate IL-22 expression, which increases epithelial AMPs, and IL-1beta production (promotes recruitment of inflammatory cells)
2. microbiota prime innate immunity by stimulating mucin production, IgA, and antimicrobial peptides (AMPs)
3. microbiota stimulate IL-22 expression, which increases epithelial AMPs, and IL-1beta production (promotes recruitment of inflammatory cells)
question
Microbiota and Protection Against Enteric Pathogens
answer
environment in which a microbiome lives
example - the oral cavity
example - the oral cavity
question
habitat
answer
all the living organisms plus physical and chemical constituents in an environment
example - the oral cavity
example - the oral cavity
question
Ecosystem
answer
study of microbes in their natural environments
question
microbial ecology
answer
diversity and abundance of microbes is controlled by resources and environmental conditions
activities of microbial communities and affect the chemical and physical properties of their habitats
activities of microbial communities and affect the chemical and physical properties of their habitats
question
Microbiome and its environment
answer
each species contributes something to the microbiome for the good of all the members
question
cooperation
answer
each species must compete with others for its niche
question
competition
answer
bacteriocins, other antibacterial proteins, and metabolites that deter other species from growing
example - colicins produced by E. coli
example - colicins produced by E. coli
question
warfare
answer
digestion
synthesis of vitamins, other nutrients, and a large collection of metabolites
out-compete certain pathogens
synthesis of vitamins, other nutrients, and a large collection of metabolites
out-compete certain pathogens
question
Gut Microbiome Assists in
answer
our behavior
development of our immune system
development or prevention of obesity
development of inflammatory disease
development or prevention of cancer
success or failure of cancer immunotherapy
development of our immune system
development or prevention of obesity
development of inflammatory disease
development or prevention of cancer
success or failure of cancer immunotherapy
question
Gut Microbiome affects
answer
of the almost 200 species, most are
actinobacteria
bacteroidetes
firmicutes
actinobacteria
bacteroidetes
firmicutes
question
Species of the Gut Microbiome
answer
highest bacterial content
anaerobic environment
microbiota is incredibly stable (like a fingerprint)
bacteria firmly attached (usually with the help of pili attaching to mucus or mannose sugars)
anaerobic environment
microbiota is incredibly stable (like a fingerprint)
bacteria firmly attached (usually with the help of pili attaching to mucus or mannose sugars)
question
Large Intestine
answer
ciprofloxacin decreases diversity of gut microbiome during and after 5-day course. It took four weeks to return to almost normal after treatment, but some failed to return
Clindamycin reduces diversity in the Bacteroides gneus and led to increase in highly antibiotic resistant colonies. Took up to 2 years to return to normal
Clostridium difficile can proliferate after a round of antibiotics and release enterotoxins, leading to antibiotic-associated colitis
Clindamycin reduces diversity in the Bacteroides gneus and led to increase in highly antibiotic resistant colonies. Took up to 2 years to return to normal
Clostridium difficile can proliferate after a round of antibiotics and release enterotoxins, leading to antibiotic-associated colitis
question
Antibiotics effects on gut microbiota
answer
skin is formidable barrier to penetration by microbes
sweat glands, which are moist, contain their own normal flora different from epidermis
sweat glands, which are moist, contain their own normal flora different from epidermis
question
Skin Microbiota
answer
sebaceous glands nutrient rich supporting:
proprionibacteria, staphylococci, corynebacteria
proprionibacteria, staphylococci, corynebacteria
question
Bacteria of Sebaceous Glands
answer
generally cannot grow due to low moisture content, acidic pH, high salt, and defensins
question
Microbial Transients and Skin
answer
bacteria proliferation occurs in the mucous membranes of upper respiratory tract
pathogenic bacteria generally start in nasopharynx
most bacteria from air is trapped in nasal passages
lower respiratory tract kept sterile due to cilia pushing particles upward, away from lungs
pathogenic bacteria generally start in nasopharynx
most bacteria from air is trapped in nasal passages
lower respiratory tract kept sterile due to cilia pushing particles upward, away from lungs
question
respiratory tract Microbiome
answer
pathogen that causes meningitis
attaches to nasal epithelium via type IV pili
attaches to nasal epithelium via type IV pili
question
Nesseria Meningitidis
answer
Streptococcus Mutans
Lactobacillus
Streptococcus sobrinus
Candida albicans (yeast)
Lactobacillus
Streptococcus sobrinus
Candida albicans (yeast)
question
Bacteria of Salivary Domain of Oral Cavity
answer
Porphyromonas gingivalis
Actinobacillus
Fusobacterium
Actinobacillus
Fusobacterium
question
Bacteria of Gingival Domain of Oral Cavity
answer
polysaccharides
proteins
DNA that have attractive and repulsive forces
all hold the biofilm together and give it shape
proteins
DNA that have attractive and repulsive forces
all hold the biofilm together and give it shape
question
extracellular matrix of biofilm
answer
1. motile bacteria approach surface
2. after sensing surface, contact is established using pili or fimbriae, which support surface crawling and contribute to 3D architecture of biofilm
3. contact triggers the release of adhesive extracellular matrix components, mediating irreversible binding
4. microcolonies become foundation of mature biofilm with distinct physiological properties, including antibiotic resistance and immune-system resilience
2. after sensing surface, contact is established using pili or fimbriae, which support surface crawling and contribute to 3D architecture of biofilm
3. contact triggers the release of adhesive extracellular matrix components, mediating irreversible binding
4. microcolonies become foundation of mature biofilm with distinct physiological properties, including antibiotic resistance and immune-system resilience
question
Biofilm Devolpment
answer
singular bacteria released from biofilms that trigger the start of a new biofilm
question
Planktonic bacteria
answer
Legionella pneumophila
was present in the water line during routine treatment
was present in the water line during routine treatment
question
Bacteria that caused death of dental patient
answer
bacteria attach to surfaces of teeth or gums via sticky polysaccharide (dextran)
certain bacteria generate localized changes in oxygen and pH (dental caries)
certain bacteria generate localized changes in oxygen and pH (dental caries)
question
Salivary Domain
answer
many anaerobic bacteria proliferate in the deep crevices near the borders of teeth and gums
question
Gingival Domain
answer
biofilm of bacteria encased in polysaccharides and extracellular polymers and salivary products on the tooth
caused by bacteria that produce acids (like lactic acid) that lower the pH near the tooth and dissolve the calcium phosphate that makes up the tooth
promoted by diets high in sucrose
caused by bacteria that produce acids (like lactic acid) that lower the pH near the tooth and dissolve the calcium phosphate that makes up the tooth
promoted by diets high in sucrose
question
dental plaque
answer
streptococcus mutans and streptococcus sobrinus
question
Bacteria involved in dental caries
answer
an example of how one member of a microbiome can control the growth of another member
Streptococcus salivarius controls Streptococcus mutans participation in biofilm formation through production of fructanase
Streptococcus salivarius controls Streptococcus mutans participation in biofilm formation through production of fructanase
question
Commensal Streptococci
answer
live organism that is believed to provide benefit to the host when ingested
question
probiotic
answer
food ingredient that supports the growth of one or more members of the microbiota
question
prebiotic
answer
colonization of the bacteria, while beneficial, only lasts about 1-2 weeks.
this is because we need to provide nutrients for these bacteria and they must compete with existing bacteria
this is because we need to provide nutrients for these bacteria and they must compete with existing bacteria
question
Use of Probiotics
answer
ability of a parasite to inflict damage to host
question
pathogenicity
answer
growth of any microbe in a host, good or bad
question
infection
answer
degree of pathogenicity
determined by invasiveness, toxicity, and other factors produced by a pathogen
determined by invasiveness, toxicity, and other factors produced by a pathogen
question
virulence
answer
injury to host that impairs function
question
disease
answer
cause disease only in the absence of normal host immunity
question
opportunistic pathogens
answer
binds iron, making it unavailable to microbes and slowing their growth
question
transferrin
answer
a virulence factor that counters transferring by binding up iron
question
siderophores
answer
follows attachment of parasite
growth and production of virulence factors
some of these virulence factors are toxic, cause tissue damage, cause further invasiveness, and induce inflammation
growth and production of virulence factors
some of these virulence factors are toxic, cause tissue damage, cause further invasiveness, and induce inflammation
question
Invasion
answer
escape of antibody response through antigenic variation, inactivation of antibody, or by intracellular growth
Neisseria gonorrhoeae produces a protease that degrades IgA
Staphylococcus Aureus makes IgG-binding protein (protein A) - prevents antibody from activating complement proteins, being an opsin, and masks bacteria from detection
Neisseria gonorrhoeae produces a protease that degrades IgA
Staphylococcus Aureus makes IgG-binding protein (protein A) - prevents antibody from activating complement proteins, being an opsin, and masks bacteria from detection
question
Evasion
answer
mycobacteria, francisellae, brucellae, chlamydiae, and rickettsiae
control of these infections requires T-helper cell response to activate macrophages to kill or create a granuloma (wall) around the infected cell
control of these infections requires T-helper cell response to activate macrophages to kill or create a granuloma (wall) around the infected cell
question
Bacteria that grow intracellularly
answer
inhibition of phagolysosome fusion (legionella, mycobacterium tuberculosis, chlamydia)
resistance to lysosomal enzymes (Salmonella typhimurium, Coxiella, Ehrlichia, Mycobacterium leprae, Leishmania)
Adaptation to cytoplasmic replication (Listeria, Francisella, Rickettsia)
resistance to lysosomal enzymes (Salmonella typhimurium, Coxiella, Ehrlichia, Mycobacterium leprae, Leishmania)
Adaptation to cytoplasmic replication (Listeria, Francisella, Rickettsia)
question
Bacterial methods to evade phagocytic killing
answer
hyaluronidase
collagenase
Streptokinase
coagulase
hemolysins
leukocidins
alpha-toxin
collagenase
Streptokinase
coagulase
hemolysins
leukocidins
alpha-toxin
question
Virulence Factors
answer
breaks down hyaluronic acid at skin to help spread throughout the body
produced by Staphylocossus and Streptococcu
produced by Staphylocossus and Streptococcu
question
hyaluronidase
answer
breaks down collagen
produced by organisms that cause gas gangrene
produced by organisms that cause gas gangrene
question
Collagenase
answer
produced by streptococci
binds to inactive zymogen plasminogen, resulting in production of active plasmin, breaking down fibrin
binds to inactive zymogen plasminogen, resulting in production of active plasmin, breaking down fibrin
question
Streptokinase
answer
produced by staphylococci
cause of boils, abscesses, and pimples
causes clots by converting fibrinogen to fibrin
helps staphylococci resist phagocytosis
cause of boils, abscesses, and pimples
causes clots by converting fibrinogen to fibrin
helps staphylococci resist phagocytosis
question
coagulase
answer
break down RBCs or any cell membrane through phospholipase activity
helps bacteria to obtain iron and break down membrane of phagocytosis
produced by bacteria that infect the skin or the back of the throat
helps bacteria to obtain iron and break down membrane of phagocytosis
produced by bacteria that infect the skin or the back of the throat
question
hemolysins
answer
specifically attack white blood cells
question
leukocidins
answer
produced by staphylococcus
pore forming cytotoxin released as monomers
7 identical subunits oligomerize in cytoplasmic membrane of target cells
forms a pore releasing contents of the cell
in RBCs hemolysis occurs
pore forming cytotoxin released as monomers
7 identical subunits oligomerize in cytoplasmic membrane of target cells
forms a pore releasing contents of the cell
in RBCs hemolysis occurs
question
alpha-toxin
answer
infection and growth of bacteria into blood
life threating outcome of some skin infections with staphylococcus aureus
life threating outcome of some skin infections with staphylococcus aureus
question
Septicemia
answer
staphylococcus aureus lyses erythrocytes through secretion of hemolytic toxins, then binds hemoglobin at its cell wall
iron containing heme cofactor is then extracted from hemoglobin and passed through cell membrane
heme is degraded to release iron for the staphylococcus aureus bacterium
iron containing heme cofactor is then extracted from hemoglobin and passed through cell membrane
heme is degraded to release iron for the staphylococcus aureus bacterium
question
staphylococcus aureus and septicemia
answer
transient entry of bacteria into the blood
happens in many dental procedures that allow entry of streptococcus mutans into the bloodstream
happens in many dental procedures that allow entry of streptococcus mutans into the bloodstream
question
bacteremia
answer
Streptococcus mutans can sometimes colonize heart valves, leading to infective endocarditis
most frequently detected bacteria in diseased heart valve tissues
most frequently detected bacteria in diseased heart valve tissues
question
Streptococcus Mutans and Bacteremia
answer
based on composition of and structure of rhamnose glucose polysaccharide (RGP) associated in its cell wall
S. mutans c
S. mutans e
S. mutans f
S. mutans k
S. mutans c
S. mutans e
S. mutans f
S. mutans k
question
four strains of streptococcus mutans
answer
persist in cytoplasm of coronary artery endothelial cells
seem to be associated with collagen and laminin binding activity of protein Cnm
this collagen and laminin is normally found in the ECM of the heart valve
seem to be associated with collagen and laminin binding activity of protein Cnm
this collagen and laminin is normally found in the ECM of the heart valve
question
Streptococcus mutans e and f
answer
extracellular virulence factors that often cause host damage at site far removed from focus of infection
Clostridium botulinum toxins coded by lysogenic bacteriophage
Corynebacterium diphtheriae toxin genetic information is contained in prophage - carried by pathogenic strains and stimulated when iron concentration is low
Clostridium botulinum toxins coded by lysogenic bacteriophage
Corynebacterium diphtheriae toxin genetic information is contained in prophage - carried by pathogenic strains and stimulated when iron concentration is low
question
Exotoxins
answer
generally excreted
gram positive or negative bacteria
heat labile - usually protein
specific action
highly toxic
highly immunogenic
usually does not produce fever
gram positive or negative bacteria
heat labile - usually protein
specific action
highly toxic
highly immunogenic
usually does not produce fever
question
Exotoxin Properties
answer
produced by corynebacterium diphtheriae of the nasopharynx
inhibits eukaryotic protein synthesis (immunity induced by diptheria-pertussis-tetanus (DPT) vaccine)
Fragment B - recognizes specific receptors and promotes entry of Fragment A
Fragment A - catalyzes reaction between NAD and EF-2 involved in protein synthesis, which inactivates EF-2 by adding ADP-ribose to it
inhibits eukaryotic protein synthesis (immunity induced by diptheria-pertussis-tetanus (DPT) vaccine)
Fragment B - recognizes specific receptors and promotes entry of Fragment A
Fragment A - catalyzes reaction between NAD and EF-2 involved in protein synthesis, which inactivates EF-2 by adding ADP-ribose to it
question
Diphtheria toxin
answer
half of NAD
question
ADP-ribose
answer
blocks release of acetylcholine at nerve-muscle junctions, preventing muscle contraction (flaccid paralysis)
clinical syndrome - bilateral cranial neuropathies and descending muscle weakness, slurred speech, diplopia, dysphagia, bilateral ptosis, a sluggish pupillary response to light, bilateral CN VI palsies
produced by Clostridium Botulinum
clinical syndrome - bilateral cranial neuropathies and descending muscle weakness, slurred speech, diplopia, dysphagia, bilateral ptosis, a sluggish pupillary response to light, bilateral CN VI palsies
produced by Clostridium Botulinum
question
Botulinum toxin
answer
does not grow well win humans, but does grow in improperly processed food
question
Clostridium Botulinum
answer
produced by clostridium tetani, which is introduced into the body by deep puncture wounds
spastic paralysis by binding to lipid in nerve synapses and blocking release of glycine and GABA from inhibitory motor neurons
spastic paralysis by binding to lipid in nerve synapses and blocking release of glycine and GABA from inhibitory motor neurons
question
Tetanus Toxin
answer
exotoxins that act in the small intestine
cause diarrhea
pathogens enter body in contaminated food or water
staphylococcus aureus enterotoxin produced by growth of bacteria in food
other bacteria colonize the small intestine before producing enterotoxin (Escherichia coli and Salmonella)
cause diarrhea
pathogens enter body in contaminated food or water
staphylococcus aureus enterotoxin produced by growth of bacteria in food
other bacteria colonize the small intestine before producing enterotoxin (Escherichia coli and Salmonella)
question
Enterotoxins
answer
causes life-threatening diarrhea by producing enterotoxin produced by lysogenic filamentous bacteriophage CTX-phi
B subunit - recognizes animal cell receptor
A1 subunit - produces toxic effect by activating adenyl cyclase
B subunit - recognizes animal cell receptor
A1 subunit - produces toxic effect by activating adenyl cyclase
question
Vibrio Cholerae
answer
lipopolysaccharides or lipooligosaccharides derived from outer membrane of gram negative bacteria, released on lysis
cause fever and other systemic toxic effects to host
specifically the Lipid A of lipopolysaccharide
can induce inflammation (host response)
can lead to death by hemorrhagic shock
LPS binds to specific receptors (TLR4 - Toll-like receptor 4)f
cause fever and other systemic toxic effects to host
specifically the Lipid A of lipopolysaccharide
can induce inflammation (host response)
can lead to death by hemorrhagic shock
LPS binds to specific receptors (TLR4 - Toll-like receptor 4)f
question
Endotoxins
answer
loss of virulence
question
attenuation
answer
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