question
What can be confirmed by Koch's Postulates?
answer
That a pathogen is the cause of a particular disease
question
Define virulence
answer
the relative ability of a pathogen to cause disease
question
What are the steps of virulence?
answer
Infection process
1. Exposure (to pathogens)
2. Adherence (to skin or mucosa)
3. Invasion (through epithelium)
4. Multiplication
Disease process
1. Toxicity/Invasiveness (further growth)
2. Tissue or systemic damage
1. Exposure (to pathogens)
2. Adherence (to skin or mucosa)
3. Invasion (through epithelium)
4. Multiplication
Disease process
1. Toxicity/Invasiveness (further growth)
2. Tissue or systemic damage
question
How does a pathogen adhere to a cell?
answer
- Receptors called adhesins (glycoproteins or lipoproteins
- Bacterial capsule (sticky and contains receptors)
- Bacterial capsule (sticky and contains receptors)
question
All bacterial cells have capsules. (T/F)
answer
False
question
Fimbriae, flagella, and pili are all examples of _____ structures found in some bacteria.
answer
attachment
question
Define colonization
answer
the presence and growth of microorganisms within a host but without tissue invasion or damage; formation of biofilm (example- cavities (plaque))
question
What is the most important factor in affecting pathogen growth?
answer
Availability of nutrients (amino acids, sugars, organic acids, etc.)
question
Define invasion
answer
ability of a pathogen to spread and cause disease (enhances by enzymes that interfere with normal host defense mechanisms- clotting)
question
How can virulence be measured?
answer
Can be estimated from experimental studies of the LD50 (amount of an agent that kills 50% of the animals in a test group)
question
Define attenuation
answer
decrease or loss of virulence
question
Why are attenuated strains valuable to clinical medicine?
answer
often used for the production of viral vaccines (yellow fever vaccine)
question
What are pathogenicity islands?
answer
Clustered genes that direct invasion
question
How are pathogenicity islands acquired?
answer
horizontal gene transfer
question
What is an opportunistic infection?
answer
one caused by organisms that do not cause disease in healthy hosts (remain latent until host is compromised)
question
___________ is the growth of microorganisms NOT normally present within a host.
answer
Infection
question
Following exposure to a pathogen, events leading to disease—in the correct order—are
answer
Adherence, Invasion, infection, toxicity
question
Adherence factors include ALL of the following EXCEPT
a) capsules
b) fimbriae
c) lipopolysaccharide layer
d) flagella
a) capsules
b) fimbriae
c) lipopolysaccharide layer
d) flagella
answer
lipopolysaccharide layers
question
Growth of a microorganism after entering a host is called
answer
colonization
question
Which of the following does NOT occur during the development of dental caries?
answer
Oral microflora produce high concentrations of exoenzymes when sucrose is present.
question
The ability of a pathogen to enter a cell, spread, and cause disease is termed
answer
Invasion
question
A bacterial infection becomes a disease when
answer
A microorganism that is established and growing in a host causes is damage and injury that impairs host function
question
_____________can vary between strains of an organism depending on the ability to adhere, colonize, and invade a host.
answer
Virulence
question
___________organisms are valuable in the production of vaccines.
answer
Attenuated
question
Organism X has an L D50 of 2 × 102, and organism Y has an L D50 of 3 × 104. Which organism is more virulent?
answer
Organism X
question
Which of the following is NOT true of human gut microbes?
a) They produce and excrete amino acids.
b) They are involved in the "maturing" of the digestive tract.
c) The population size is low, but the diversity is high.
d) They help utilize polysaccharides.
a) They produce and excrete amino acids.
b) They are involved in the "maturing" of the digestive tract.
c) The population size is low, but the diversity is high.
d) They help utilize polysaccharides.
answer
The population size is low, but the diversity is high
question
The host-microbiome supraorganism refers to
answer
a body and all of its associated microbes
question
Which of these microorganisms is most likely to be found in the human stomach?
Neisseria gonorrhoeae
Streptococcus mutans
Streptococcus sobrinus
Helicobacter pylori
Neisseria gonorrhoeae
Streptococcus mutans
Streptococcus sobrinus
Helicobacter pylori
answer
Helicobacter pylori
question
Which of the following is NOT a major question in the Human Microbiome Project?
a) Are differences in the relative abundance of different bacteria important?
b) Do differences in the human microbiome correlate with differences in human health?
c) Is there a correlation between microbial population structure and host genotype?
d) How can we reduce the number of microbes on the human body?
a) Are differences in the relative abundance of different bacteria important?
b) Do differences in the human microbiome correlate with differences in human health?
c) Is there a correlation between microbial population structure and host genotype?
d) How can we reduce the number of microbes on the human body?
answer
How can we reduce the number of microbes in the human body?
question
Normal microbiota helps to ________ colonization of pathogenic organisms
answer
Prevent
question
The damaged areas of teeth caused by organic acids produced by dental plaque are called
answer
dental caries
question
Which of the following environmental and host factors influence the composition of the resident microbiota on the skin?
a) weather
b) age
c) hygiene
d) age, personal hygiene, and weather
a) weather
b) age
c) hygiene
d) age, personal hygiene, and weather
answer
Age, personal hygiene, and weather
question
Because they are Gram negative, E. coli, Salmonella, and Shigella all produce
answer
endotoxins
question
Pathogens that can secrete ______________ are more virulent because of the organism's potential to spread in the host.
answer
hyaluronidase
question
Streptokinase works to ___________ fibrin clots while coagulase works to ___________ fibrin clots.
answer
dissolve/promote
question
Endotoxins are the secreted products of living cells, whereas exotoxins are cell bound and released in large amounts ONLY when the cells lyse. (T/F)
answer
False
question
Exotoxins classified as A B toxins damage cells by
answer
using the B subunit to attach to the target cell while the A subunit enters and inhibits protein synthesis.
question
Lysozyme is found throughout our bodies to protect us from infection. Some bacteria can evade this defense by
answer
altering their peptidoglycan
question
All of the following are enzymes that increase virulence EXCEPT
a) proteases
b) lipases
c) cellulases
d) nucleases
a) proteases
b) lipases
c) cellulases
d) nucleases
answer
cellulases
question
The vagina of an adult female is
answer
weakly acidic
question
Diphtheria toxin is
answer
an AB toxin
question
Which of the following is TRUE about research on the human microbiome?
a) Cultivation was unimportant in studying its microbial diversity.
b) None of the answers are correct.
c) Advanced nucleic acid sequencing techniques were needed before a good understanding of its microbial abundance and diversity could be developed.
d) Culture-dependent techniques fully Culture-dependent techniques fully elucidated its microbial diversity.microbial diversity.
a) Cultivation was unimportant in studying its microbial diversity.
b) None of the answers are correct.
c) Advanced nucleic acid sequencing techniques were needed before a good understanding of its microbial abundance and diversity could be developed.
d) Culture-dependent techniques fully Culture-dependent techniques fully elucidated its microbial diversity.microbial diversity.
answer
Advanced nucleic acid sequencing techniques were needed before a good understanding of its microbial abundance and diversity could be developed.
question
Genes for antiphagocytic proteins, exotoxins, and adherence that are clustered together on a bacterial chromosome are called
answer
pathogenicity islands
question
Which of the following toxins is NOT a cytolytic exotoxin?
phospholipase
leukocidin
Shiga toxin
hemolysin
phospholipase
leukocidin
Shiga toxin
hemolysin
answer
Shiga toxin
question
What is the difference between Bacteremia and Septicemia
answer
Simple presence of bacteria in the blood vs presence and multiplication of bacteria in the blood
question
Which kind of disease is an example of microbial colonization/ biofilm formation?
answer
Dental caries (cavities)
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