Micro Flashcards
what is MRSA known to be resistant to
beta lactam antibiotics
what antibiotics is susceptable to MRSA
vancomyosin or linezolid
Common antibiotic for strep pneumo
penicillin
common antibiotic for enterococcus faecalis
ampicillin and vancomycin
what is CNA agar selective for
GPO
alpha hemolysis principle
partial breakdown of haemoglobin
beta hem principle
complete breadown on haemoglobin
gamma hem principle
bacteria are non hemolytic
principle and purpose of catalase test
enzyme that converts hydrogen peroxide into water and oxygen
differentiates strep (neg) and staph (pos)
false pos of catalase
rbc carry over
enterococci
false neg of catalase
old colonies
principle and purpose of coagulase
converts fibrinogen to fibrin using rabbit plasma on a BAP plate to detect staph aureus (pos)
false pos of coagulase test
staph isolated on selective media
principle and purpose of DNAse
DNAse enzyme cleaves DNA to leave a colorless media
differentiate of aureus (pos) and micrococcus (neg)
what is the gold standard of MRSA ID
PCR - but using Oxacillin disc test works
location and cause of strep pyo (GAS)
pharyngitis causing strep throat
location and cause of strep agal (GBS)
gential tract causing neonatal sepsis and meningitis
location and cause of strep pneumo
URT fllora causing pneumonia, eye and ear infection
location and cause of viridian strep
mouth and URT flora causing heart damage
location and cause of enterococci
GI flora causing UTI and wound infections
what antibiotic can enterococci become resistant to
vancymycin resistancve enterococci (VRE)
what does a pos PYR look like
red dot on poked disc= pos
what is bacitracin (Taxos A) positive result
any zone of inhibition seen
how to set up a CAMP test
S aureus middle line, then perpendicular lines to the middle line
what is a pos CAMP test look like and what organism
arrow heads as GBS is pos
what does a pos BEA look like
black coloration
what does pos NaCl tolerance test look like
purple to green = pos
BUT if no color change and BAP grew, then still pos
principle of decarboxylase
medium contains glucose and bromcresol purple. tubes will turn yellow (acidic) incubated due to glucose fermentation. tubes revert to purple (basic) if decarboxylation occurs.
what color should the control tubes for decardboxylase be
yellow - we want to make sure glucose ferments and its the bacteria that decarboxylases.
Common characteristic of enterobateriaceae
GNB
- ferment glucose
- nitrate to nitrITES
- ox neg
-non spores
principle of cytochrome oxidase test
TMPD interacts with the ETC of cytochrome C making dark purple indophenol. (interacts w bacteria containing cytochrome C)
false negative of oxidase test
selected off MAC - use only fresh BAP 12-24 hrs
principle of TSI
carb fermentation (glucose, lactose, sucrose)
H2S production
gas production
what are non fermenters TSI
K/K (red)
what are non lactose fermenter TSI
K/A
red/yellow - glucose fermented but not lactose
critrate principle and pos
turns blue = pos due to alkaline products produced
indole principle and pos
hydrolyze triptophan to form indole which is detected using kovacs
cherry red = pos
malonate pos colour
change of blue to green = pos
phenylalanine test pos
add ferric chloride - green = pos
urease test pos
cherry red = pos
OF test principle and pos
aerobic = oxidation to gluconic acid
anaerobic = fermentation to triose molecules
yellow = pos
blue = neg (gluose not used)
