lab tests Flashcards
catalase test
differentiates strep (neg.) and staph (pos.)
–>3% hydrogen peroxide
positive reaction = bubbles
slide coagulase test
looks for clumping factor
+ reaction: clumps
controls: staph aur. + and staph epi. -
cefoxitin disc
less than or equal to 19 –> methicillin resistant
more than or equal to 20 –> methicillin sensitive
bacitracin disk
defined zone of inhibition: sensitive
no zone of inhibition: resistant
optochin disc
greater than or equal to 14 –> sensitive
less than or equal to 13 –> resistant
oxidase test
+ reaction: turns violet
- reaction: no color change
spot indole
+ reaction: blue green color
- reaction: no color change
tsi
slant: yellow (A) red (K)
butt: yellow (A) red (K) or neutral (N)
gas: large amounts (G) or small amounts (g)
H2S: turns black
urease
+ reaction: pink
- reaction: yellow
methyl red
+ reaction: turns red
- reaction: stays yellow
vp
+ reaction: turns red
- reaction: no color change
