staph + strep unknown LAB QUIZ

staph is gram ___

positive

strep and entero is gram ___

positive

what is the shape of staph

cocci, grape clusters

what is the shape of strep and entero

cocci, chains

normal microbiota of staph is found on

skin

normal microbiota of strep is found on

pharynx/upper throat

normal microbiota of entero is found on

gut/intestines

staph is catalase ____

positive

strep and entero is catalase ____

negative

what staph species is the most virulent

s aureus

salt tolerance of staph

facultative halophiles

what is a mannitol fermenter

microbe that can break down mannitol

what is mannitol

sugar alcohol

what is the medium for mannitol test

mannitol salt agar, msa

msa tests for both ______ and ________

salt tolerance, mannitol fermentation

what percent of NaCl is in msa

7.5

whats the ph indicator for mannitol

phenol red

positive mannitol fermentation

drop in ph, turns YELLOW

non mannitol fermenters

stays red

what organism does MANNITOL single out from the rest? and what is its result?

s. epidermidis, negative/red

what is coagulation

clotting of blood plasma proteins

what is the medium for coagulase test

rabbit plasma

what organism does COAGULASE single out from the rest? and what is its result?

s. aureus, positive/clots

what is alpha toxin

toxin produced by bacteria that damages host cells by forming holes in their membranes, causing cell death

production of alpha toxin causes _____ __________

beta hemolysis

what is the MEDIUM for alpha toxin test

sheep blood agar, BAP

alpha toxin POSITIVE appearance:

yellow halo

alpha toxin NEGATIVE appearance

gray, no halo

what organism does ALPHA TOXIN single out from the rest? and what is its result?

s aureus, positive/yellow halo

what are the three antibiotics covered:

novobiocin, bacitracin, sxt

whats the MEDIUM for novobiocin susceptibility

tryptic soy agar, TSA

novobiocin sensitive is

16 mm and over

novobiocin resistant is

15 mm and under

what organism does NOVOBIOCIN single out from the rest? and what is its result?

s. saprophyticus, resistant

media types: TSA

general purpose, supportive

media types: MSA

selective and differential

media types: BAP

enrichment and differential

media types: rabbit plasma

differential

which medium are staph organisms routinely inoculated for initial isolation

MSA

what is hemolysis

breakdown of rbc

what is gamma hemolysis

no hemolysis

what is alpha hemolysis

partial hemolysis, green brown discoloration

what is beta hemolysis

complete lysis of rbc, clear zone around colonies

strong beta hemolysis

large clear zone

weak beta hemolysis

small clear zone

what is the MEDIUM for hemolysis test

sheep blood agar, BAP

what is camp factor

protein and virulence factor that enhances hemolysis on blood agar

what is the MEDIUM for camp factor

sheep blood agar, BAP

camp factor POSITIVE appearance

arrowhead shaped hemolysis at junction

camp factor NEGATIVE appearance

no change

what organism does CAMP FACTOR single out from the rest? and what is its result?

s. agalactiae, positive

what is the MEDIUM for bacitracin and sxt susceptibility

brain heart infusion agar, BHIA

bacitracin and sxt SENSITIVE

any zone of inhibition

bacitracin and sxt RESISTANT

0mm

purpose of hippurate hydrolysis

detects if an organism can hydrolyze hippurate

what is the medium for hippurate hydrolysis

hippurate disk

what is the reagent for hippurate hydrolysis

ninhydrin

hydrolyzed hippurate appearance

purple

unhydrolyzed hippurate appearance

colorless

what organism does HIPPURATE HYDROLYSIS single out from the rest? and what is its result?

s. agalactiae, positive/purple

purpose of bile esculin hydrolysis

detects if an organism can hydrolyze esculin in the presence of bile

what is the MEDIUM for bile esculin hydrolysis

bile esculin agar slant, BEA

explain the process of hydrolyzed esculin:

group D strep hydrolyzes esculin into esculetin. esculetin and ferric citrate forms a black precipitate

bile esculin: selective agent

1% oxbile to inhibit non group D strep

bile esculin: differential agent

esculin

bile esculin: indicator

ferric citrate

hydrolyzed esculin appearance

black

unhydrolyzed esculin appearance

no change/tan

what organism does BILE ESCULIN single out from the rest? and what is its result?

e. faecalis, positive/black

purpose of tolerance to 6.5% NaCl

determines if bacteria can grow in high salt concentrations

what is the MEDIUM for NaCl

6.5 nacl broth

nacl broth tolerant appearance

turbidity, growth

cant tolerate nacl broth appearance

clear, no growth

what organism does NACL single out from the rest? and what is its result?

e. faecalis, positive/turbid

media types: BHIA

enrichment and general purpose/supportive

media types: hippurate disks

differential

media types: BEA

selective and differential

media types: nacl

selective

what tests use BAP

alpha toxin, hemolysis, camp factor