Final Lab Practical Flashcards
why is coccidioides immitis considered to be a dimorphic fungus?
It can grow as yeast or as mold depending on conditions
what is the difference between mold and yeast (macro and micro)?
yeast are creamy looking, moist, large and oval
mold are not creamy or moist
What are the growth differences between fungus and bacteria?
fungi-grow slower, at a lower temperature, and lower pH
what is the difference between vegetative hyphae and aerial hyphae?
Vegetative- grow down or into agar
aerial- grow above agar surface
what is the difference between sporangiospores and conidiospores?
spor- spores grow inside of a sack
conid- spores at the end of hyphae
how are molds identified in the laboratory?
macroscopic and microscopic appearance
Define bacteriophage
lytic
plaque
- virus that infects only bacteria
- lyses or bursting of the host cell
- area of clearing representing a virus blowing up a bacteria
what is the purpose of making dilutions of the T-4 virus?
you need a countable plate of plaques
Define obligate intracellular parasite
lytic cycle
- organisms that can only grow inside another living host cell
- cycle in which virus infects and then bursts their host once the appropriate number of viruses have been synthesized, killing the host cell
How does a medium used for bacterial growth differ from media used for bacteriophage growth?
the virus uses the bacteria on the media to grow/infect. ordinary agar/broth but bacteria is used as host cell
Differentiate between staphyloccocus and streptococcus by the catalase test
staph-positive, bubbles
strep-negative, no bubbles
what is the principle in the catalase and coagulase tests, what is the media used for each?
cat- does bacteria produce catalase enzyme, H2O2 (bubbles)
coag-does bacteria produce coagulase enzyme, rabbit plasma (white clumps)
calculate the titer of phage in the original sample given teh numbe of plaques and dilution of the plate.
what is the unit??
plaque count X dilution factor X sample amount = PFU’s/ml of sample
PFU’s/ml
differentiate between the two species of Staphylococcus by the coagulase test and reaction on mannitol salt agar
BE ABLE TO SPELL!!
Staphylococcus aureus- coagulase (+), yellow salt agar (+)
Staphylococcus epidermidis- coagulase (-), no change in media (-)
How is mannitol salt agar both a selective and differential media?
selective because of high salt and differential because of mannitol fermentation (if positive, bacteria will produce acid, which will change the pH of media, and change the color of media)
Determine species of Micrococcus by pigmentation or nitrate test result. BE ABLE TO SPELL
Micrococcus roseus- pink hue, (+) nitrate test (red at first, or no red after zinc)
Micrococcus luteus- yellow hue, (-) nitrate test(no color at first, red after zinc)
What is the gram result, morphology, and arrangement of staphylococcus and micrococcus?
gram (+), cocci, in clusters
Where are staphylococcus and micrococcus found in the body?
skin and mucous membranes
define carrier
MRSA
nosocomial
- a person who harbors a pathogen but exhibits no symptoms
- methylin resistant staphylococcus aureus
- health-care acquired disease
name two substances that staphylococcus aureus produces to cause disease.
- coagulase enzyme
2. catalase enzyme
when do staphylococcus epidermidis and micrococcus cause disease?
they opportunistic pathogens
describe the difference between the types of hemolysis.
alpha-bruised
beta-lysed, clearing
gamma-no change
why do you use the streak-stab method for blood agar inoculations?
let’s you see hemolysis better
State the atmosphere used to grow streptococcus.
candle-jar, they are microaerophiles
