general characteristics of staph and strep

what do staph species produce (with examples and what they do)

exotoxins; leukotoxin (kills WBC), enterotoxin (food poisioning), TSS1 (toxic shock-1), protein A (blocks phagocytosis)

describe the reaction in a positive catalase rxn

H2O2>>O2+H2O

are staph species generally considered motile or non-motile

non-motile (not moving)

describle the principle in a coagulase rxn

fibrinogen+coagulase enzyme= fibrin enzyme (breaking down fibrinogen to fibrin)

what are the three ways to test for a coagulase rxn (and what do they test for)

slide (bound), tube (free), latex (bound,free, and protein A)

describe what happens in a slide coagulase

(not done as much) slide uses rabbit plasma, looking at the reaction with fibrinogen to detect bound coagulase (clumping factor): this is a RAPID test that takes approx. 10 min

describe what happens in tube coagulase

NOT rapid can take up to 24 hours to test; MAKE SURE to check at 4 hours- sometimes clots will form and will dissapear; if no clot is seen at 4 hours incubate for 24- this is testing for coagulation through fibrinolysis

describe what happens in latex coag rxn

(commonly used) this is an IMMEDIATE rxn that looks for bound coagulase (clumping factor) and protein A (found on cell wall and is exotoxin)

DNAse

not done as much (DNAse is secreted by s.areus, but other organisms can also be +)

what is MRSA

methicillin resistant: resistant to methicillin and penicillin and oxacillin (all beta lactam drugs)

how is MRSA screened

with cefoxin and/or chromagar

what causes MRSA

the mec A gene changing the PBP (penicillin binding protein)

what is chromagar

a quick screen test that turns blue when +

how is MRSA treated why isn't this treatment used first

vancomycin: not treated with this first because it causes more side effects in humans

what is VISA/VRSA

vancomycin intermediate or vancomycin resistant: not as many antibiotics are left to treat the patient

what is PYR

L-pyrrolidonyl arylamidase; test that differentiates s. areus from other staph-- +=pink -=no change

what is Novobiosin resistant and describe where its seen and what hemolysis it has

bacteria that is resitant to Novobiosin; seen on a lawning plate: commonly seen in urine infections in young females (reported out in low numbers) usuallygamma hemolytic but can beta

describe the general morphology of strep scecies

small(er), more grey in color

what hemolysis can strep species be

ALL (categorized by it!)

what is capnophillic and which species is this term associated with

likes CO2 and associated with strep species

describe a gram stain for a strep species

G+ cocci in pairs or chains

what catalase rxn does strep have

neg

what catalase rxn does staph have

pos

describe a bile solubility test

done on a tube or plate (pos rxn= clearing can be seen), reagent:deoxycholate, it changes surface tension (causing lysis)

describe a Optochin test

done on a P disc (ethylhydrocuprine HCl) used as a screening

describe a urine antigen test

repaid screening test that uses a lateral flow immunoassay: this test shows antigen in urine and antibiodies (good with people on antibiotics) --like pregnancy test a swab is stuck in the test with a reader

what is a MALDI and what's the exception(s)

a machine that differentiates and identifies different organisms by their peaks (like a mass spec machine); exception: CANNOT differentiate between s. pnemo and s. viridian's= confirmatory BILE test is needed (their peaks are to similar)

describe a LAP test

leucine aminopeptidase; detects enzyme leucine aminopeptidase (LAP) that is produced by certain bac. +test= hydrolysis of leucine substrate(Red color)

what plates can staph species grow on

blood chocolate CNA and PEA

describe the miscrodase test

(modified oxidase) its a disc that tests for cytochrome C (which is an oxidase enzyme), a + rxn is purple/blue

is micrococci commonly normal flora or pathogenic

normal flora

which antibiotics is micrococci resitant to

lysostatin R, bacitracin S

what is a Na Hippurate test

testing for enzyme: hippuricase produced by s. alaciae pos=blue/purple (shows breaking down of enzyme to glycine& benzoic acid) -specifically when the reagent ninehydrine reactes with broken down glycine

what is a salt tolerant test

where an organism is tested with concentrated amount of bile of salt to test its resilience (whether it dies or not)