N251 Exam 1 (lectures 4-5)

• bacterial cells build up protoplasm & double in size
• once doubled in size & ea. of its parts; the cell divides into 2 daughter cells (this reproduction is called binary fission) = asexual reproduction = how they reproduce

it is hardly noticeable. growth is measured by an increase in the # of bacterial cells

1. a measured quantity of specimen is planted to a streak plate - calibration - using a calibrated loop
• a single bacterium will produce a colony containing millions of bacteria
• in clinical labs the # of bacteria is quantitated depending on the measured specimen

• count the number of colonies growing x (times) per ml of urine use

1. add a specific diluted homogenized specimen to melted agar and pour into sterile petri dish - quantitative
(observe & count colonies after incubation)
2. EX: testing sterility of tissue sample for skin graft

** does NOT have any solid medium
1. inoculate empty plate
2. add melted nutrient agar
3. swirl to mix
4. colonies grow in & on solidified medium

** contains solid medium
1. inoculate plate containing solid medium
2. spread inoculum over surface evenly
3. colonies grow only on surface of medium

serial dilution of the biological samples. (for the final counting of bacterial cells, consider dilution factor)

a stepwise dilution of a substance in solution

colonies are typically ISOLATED so that we can identify them. this is considered more qualitative (can indicate heavy or light growth) than quantitative. w/ isolation you can tell if you have a pure or mixed culture

4 quadrants (1st quadrant - initial inoculum)

• minimum temp: lowest temp that permits growth = 8°C
• maximum temp: highest temp that permits growth = 48°C
• optimum temp: range of temp that promotes the highest growth rate = 37°C

EX: flayobacterium spp.
• optimum between 5°C-20°C
• snow fields, polar ice, ocean depths

• optimum between 20°C-50°C
• majority of bacteria = human pathogens

EX: bacillus stearothermophillus
• optimum between 50°C-80°C (40°C-90°C)
• habitats exposed to sun/hot springs
• can produce some bright colors of Grand Prismatic Spring & Yellowstone National Park

• optimum between 80°C and above
• soil and water assc. w/ volcanic activity

• must HAVE O2
• use respiration to get energy
• EX: pseudomonas aeruginosa

• CANNOT grow in the presence of O2
• use FERMENTATION to get energy
• EX: bacteroides fragilis

• organism can grow WITH or WITHOUT the presence of O2
• uses both fermentation AND respiration
• occurs optionally in response to circumstances rather than by nature (greater growth in O2 & lesser growth in anaerobic cond.)
• EX: e. coli; staph aureus

• require O2 BUT in SMALL amounts; higher O2 content will kill organism
• EX: helicobacter pylori & neisseria gonorrhoeae

• grows WITH or WITHOUT O2; O2 has NO effect
• growth occurs evenly throughout the culture tube
• EX: streptococci species

aerobic bacteria have mechanisms to get rid of toxic by products of aerobic metabolism whereas anaerobes DON'T

need a source of carbon from catabolized organic molecules such as proteins, carbohydrates, fatty acids, amino acids, etc

acquired from "redox" (reduction and oxidation) reactions. primary energy source is glucose metabolism

vitamins, minerals, and water (H ions)

• exponential phase - rapid growth
• stationary phase - plateau: growth levels out

• closed system: nutrient and space are finite; no mechanism to remove waste products
• four growth phases = lag, exponential (log), stationary, death

• lag phase: cells need time to adjust to the environment before reproduction; cells aren't reproducing a max rate
• exponential (log) phase: reproducing @ max rate; growth continues as long as nutritional content is sufficient & environment is favorable
• stationary phase: decline in growth rate; increase in death rate
• death phase: cells die rapidly

dead cells will sediment @ the bottom of the culture tube/flask; note max number of live cells in exponential phase

sites through which pathogens enter the body

respiratory, GI tract, urogenital, eye

hair follicles, sweat glands, cuts, bites, stabs, etc

typically forms protective barrier to most pathogens; pathogens that can cross placenta: syphilis, HIV, & toxoplasma

pathogens enter body by means other than GI route (non oral); get deposited directly into tissues; occurs in punctures by nails, thorns, needles; breaks in the skin by cuts, bites, abrasions, or surgery

• defense mechanism: dryness, acidity, toxicity, constant shedding
• cond. that foster entry: wounds, excess moisture, serious discharge

• defense mechanism: ciliated cells constantly moving mucus to throat
• cond. that foster entry: reduced mvmt. of ciliated cells as in smoking, chilling, narcotics, viral infection

• defense mechanisms: 0.2% hydrochloric acid; enzyme pepsin
• cond. that foster entry: reduced stomach acid; ingestion of antacid

• defense mechanisms: lactobacilli during childbearing years
• cond. that foster entry: reduced #'s of lactobacilli from douching, soaps, menopause, antibiotic therapy

• defense mechanisms: flushing action of urination
• cond. that foster entry: short urethra in women; incomplete or infrequent urination; sexual intercourse

directed against any organism that tries to invade the host

• skin & mucus membrane surfaces
• most pathogens enter body by binding to & penetrating mucous membranes - saliva, tears, and mucous secretions wash away potential pathogens; mucus, secreted by epithelial cells of the mucous membrane: trap pathogens; cilia (hair like projections from the epithelial cell lining the respiratory tract) - propel mucous trapped pathogens from the respiratory tract

pH
• stomach @ pH 2 - kills most ingested pathogens (heliobacter pylori only known bacteria to colonize stomach)

• body temp inhibits growth of some pathogens
• fever response inhibits growth of some pathogens

• proteases in GI tract
• bile acids
• lysozyme in saliva and tears

specialized cells phagocytize pathogens. these are WBC called polymorphonuclear leucocytes or "polys" for short. they seek out to help destroy pathogens

increased blood flow to affected area; capillaries are engorged & responsible for tissue redness & temp

tissue damage caused by a wound or by invading pathogen induces sequence of events call the _____

influx of fluid & cells from engorged capillaries into tissue

contains proteins & antibodies & contributes to tissue swelling/edema

main component of blood clotting, if bleeding occurs, influx of phagocytic cells respond to injured cells and pathogens

these changes produce the classic clinical signs of inflammation: heat(calor), reddness(rubor), edema(tumor), pain(dolor), loss of function

calor

heat

rubor

redness

tumor

edema

dolor

pain

• babies up to 3mos don't produce their own antibodies, depends on mother's antibodies (gets their mom's antibodies through placenta and breast milk)
• the older an individual gets, the more the immune sys. f(x) decreases

appears to exist a correlation btwn functioning of immune sys. and nutritional habits of individual (eat good = have a good immune sys; eat bad = bad immune sys)

• radiation & chemotherapeutic agents
• antibodies
EX: give a female antibodies for UTI, kills infecting organism as well as normal flora of the vagina; which gives yeast an opportunity to take over (overgrow) and cause a secondary infection

• AIDS, leukemia, cancers, chronic, latent diseases
EX: diabetes: high sugar in the urine, trouble voiding urine completely, stasis of urine leading to urinary infection

you've been in an accident (banged up) - that can affect immune sys (weaken it)

• splinters, bites, punctures, needles, etc
• indwelling catheters, surgeries, etc

microbes that colonize the body (external & internal - outside/inside but doesn't cause disease) w/o normally causing disease

prevents the growth of other potentially harmful bacteria
• by preventing attachment to tissue; competing for nutrients; metabolic requirements or products produced

consume large amounts of O2 = requires large amounts of O2
• decreasing amount of O2 around them prevents the growth of some aerobic organisms

produce acids, toxins, and peroxides that are toxic to harmful bacteria

• specialized immune system; you get specific responses
• includes B cell and T cell antibodies; and each have a specific target.

a marker for your body to realize when a pathogen is present in the body

• free antigens directly activate
• antibodies b cells
• defend against extracellular pathogens by binding to antigens and making them easier targets for phagocytes and complement

• antigens displayed by infected cells activate and target infected cells; destroying them and the pathogens within them
• antibodies t cells
• defend against intracellular pathogens and cancer by binding to and lysing the infected cells or cancer cells

establishment of bacterial growth on or within the host

when bacteria colonize body tissue and cause the host to react w/ an immune response

when noticeable impairment of body function occurs

when disease is caused by infectious bacteria or virus

• get a cut on your hand, doesn't become a disease. it's a loss of function
• get an infection of bacteria in lungs, it becomes a disease; it's pneumonia (impairment of body function)

any disease causing microorganism or virus

causing

the ability to cause disease

(opportunist)
• causes a disease when the host is impaired
• normal flora can become an opportunist
EX: candidiasis (yeast infection) in males and females

describes characteristics of the bacteria or virus that makes it cause disease/pathogenic

it is MORE likely to cause disease

it is LESS likely to cause disease

strep. pneumoniae - species W/ capsules that are virulent & MORE likely to cause pneumonia; species W/O capsules are avirulent, normal throat flora and NOT likely to cause pneumonia

outside the cell. do not need to invade host cells to reproduce. these pathogens reproduce in spaces and fluids surrounding cells and tissues (referred to as systemic infection). largest # of pathogens and grow on artificial media (in-vitro)
EX: staphylococci; streptococci

will reproduce inside host cells and can live outside host cells. can grow on artificial media that is enriched w/ special nutrients and growth factors. note intracellular pathogen by nature but can become intracellular under circumstances
EX: legionella, some salmonella (typhi), gonorrhoeae

can only survive and reproduce inside host cells. must grow in cell cultures
EX: chlamydia, viruses

1. transmission to susceptible host through portal of entry
2. adherence to target tissue: microorganisms must attach to host cells to avoid being expelled; depending on what type of pathogen, entry into the cell may also be required
3. colonization: susceptible host cond. must be right for bacteria to reproduce
4. damage to host (pathogenicity/virulence factors): exotoxin or endotoxin
5. exit from current host
6. survive outside long enough to find another host

proteins that act as powerful poisons systemically to humans. secreted from the bacterial cytoplasm into the surrounding areas when the organism dies. secreted by gram positive and gram negative bacteria. (made in cell but released outside the cell)
EX: staphylococcus aureus

part of the cell wall of gram negative bacteria and released from the cell wall. released only when bacteria are actively dividing or dying (not systemic). all _______ infections have same effect on the host
EX: salmonella

• exotoxin: gram positive AND gram negative species
• endotoxin: gram negative species ONLY

• exotoxin: synthesized in cytoplasm and released from cell
• endotoxin: component of cell wall

• exotoxin: protein
• endotoxin: lipopolysaccharide containing lipid A

• exotoxin: yes
• endotoxin: no

• exotoxin: generally heat labile. 60°-100°C for 30 min. destroys them
• endotoxin: heat stable. not destroyed by autoclaving

• exotoxin: each has a distinctive effect
• endotoxin: all have the SAME effect: fever, circulatory collapse, and characteristic damage to tissues

• what pts tell doctors
• diseases manifest in different ways. _____ are subjective characteristics of a disease that can be felt/sensed by the pt.
EX: pain, headache, chills, discomfort, itching, etc

• what doctors can see in pts
• ____ are objective manifestations of diseased that can be observed or measured by others
EX: swelling, rash, vomiting, diarrhea, fever, etc

• a manifested group of symptoms and signs that collectively characterize a particular disease or abnormal cond.
EX: strep throat

• best outcome-infection is eliminated WITH NO damage
• immunity, antibiotic, chemotherapy effective cure

• (pus formation) also called purulent infection
• liquid material that contains masses of WBC and leads to necrosis of tissue
• may result in formation of abscess

• long standing infection
EX: pneumonia, bladder infection, respiratory, etc

• diffuse purulent inflammation
• spreads btwn the layers of the involved tissue
• may result from an acute or chronic infection

• chronic inflammation in which granulomas are formed
• body walls off the organism
EX: TB

• infection severe enough to kill tissue causing scar formation
• severe scarring: cause loss of function of the organ
EX: hepatitis virus can cause fibrosis of the liver (cirrhosis)

it is a step by step procedure of SCIENTIFIC PROBLEM SOLVING. similar to a recipe for science. ____ is a process used to systematically investigate observations, solve problems, and test hypotheses. ____ helps scientists ensure that the theories they test are true by TESTING A HYPOTHESES WITH TESTS.