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19 Cards in this Set
- Front
- Back
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how can you do antimicrobial susceptibility testing?
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test tube serial dilutions - here, look for the MIC (concentration of antibiotic that doesn't allow growth) - also can tell MBC (usually higher concentration, here it's killing an already existant culture in a fixed amount of time). For bacteriostatic agents, MBC is higher than MIC.
also can do Disc Agar Diffusion Technique - lots of potential variablity (size of inoculum, the size of the antibiotic molecule = different diffusion radius, etc). Small molecules may look artificially beneficial, since they move farther than large molecules. incubation might also kill antibiotics. also, ONLY BACTERIOSTSTIC characteristics can be obeserved, as you're preventing lawn growth. E strips. |
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go over differentiating the streps -
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catalayse negative.
beta hemolytic = complete lysis...this means pyogenes or agalactaie. there's a ZONE of clearing and decolorization around the colony. alpha hemolysis = incomplete lysis with green/brown discoloration. gamma hemolytic = no hemolysis. beta differentiation - use BACATRACIN - if sensitive = strep pyogenes. differentiate Strep Pneumonae from viridans = both are alpha hemolytic, but only pneumonae is sensitive to OPTOCHIN. gamma hemolytics - need to tell group D (enteroccus and S. bovis) from non-d. D's will grow in BILE ESCULIN AGAR - only the enteroccus can put up with 6.5% NaCl. |
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identify staph aureus? epidermididis?
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green/yellow pigment. epidermidis does not produce the same color.
STAPH = CATALAYSE positive. only staph aureus is COAGULASE positive. |
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what are our enterobacteriacae groups we need to tell apart?
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E. coli, Klebsiella, and Proteus.
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diagnosis of UTI?
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greater than 10,000 colonies/mL = UTI. Usually by E. coli, enteroccus, klebsiella, and proteus.
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tell between e. coli and shigella/salmonella?
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on maconkey agar, only E. coli ferments lactose and changes color.
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identify proteus?
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very motile - swim on blood agar.
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why do an oxidase test?
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this is for pseudomonas in poop - remember that it can cause intestinal problems.
all members of enteroccus are oxidase negative, but pseudomonas is oxidase positive. |
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tell between e. coli, shigella, salmonella, and pretus?
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citrate test -
if they can use citrate, they're klebsiella, slamonella, and pretus. if they can't use citrate, they're e. coli and shigella. |
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talk about the TSI test -
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has three sugars (a tiny bit of glucose, lots of sucrose and fructose). Also, thiosulfate to see if it can be turned into hydrogen sulfide gas.
notation uses A for acidic, K for basic. Know that for salmonella/shigella, turn acidic at first then back to basic (pink) as they run out of glucose. E. coli will always be acidic (yellow). know that salmonella/proteus are K/a, H2s+, slank alkaline, but acid. e. coli is A/a, slant and butt acid, NO GAS. K always means salmonella/shigella/proteus. hydrogen sulfide gas is ONLY salmonella and proteus! = SAP non motile, think klebsiella and shigella. |
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talk about monomorphic vs. dimorphic and what that means -
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generally, the primary pathogens (those affecting the healthy) are dimorphic (molds at cold temp, yeats at body temp). these include histoplasma, blastomyces, coccidiodies, paracoccidioies.
the opportunistic pathogens tend to be monomorphic - aspirgillus, cryptococcus, candida |
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how can you identify shigella?
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shigella can't do anything. doesn't use citrate (stays green), can't make gas, is alkaline, etc.
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what's non motile?
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shigella and klebsiella
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what's weird about coccoidies?
what are our opportunitstic yeasts/molds? |
it's a primary fungus, so it should be dimorphic - it is, but in tissue forms SPHEREULES, not exactly yeast.
yeasts that are opportunistic are cryptosporidium and candidia. aspirgillis is an opportunistic mold. |
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what's weird about crypotococcus? what about candida?
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encapsulated, can be either primary or opportunistic pathogen. monomorphic yeast (along with candida).
candida is weird 'cause it's monomorphic, but in people makes hyphae/pseudoyphae/germ tubes. |
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when molds are grown on media asexually, what happens?
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they make spores, aka condida.
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go through the plate identification strategy
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if yeast, can't tell by appearance from bacteria.
india ink = cryptococcus, quick, for CSF. germ tubes = candida. LPCB - lactophenol cotton blue - good for fungi. scope = tease, scotch tape, slide. |
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what plate kinds are used for mycology?
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sab + chloramphenocol (SAB-C) = most bacteria don't grow.
germ tube testing = candida. Uni Yeast Tek Kits |
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what matters under the scope?
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presence/abundance/shape/placement of the CONDIDA (spores).
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