lab 14-15-18 Flashcards
how many units of TaxoA (bacitracin) is placed on the agar plate?
0.04 units
incubation temp and period Bacitracin for STAPH
18-24hr at 35-37C in ambient air
Bacitracin for STREP differentiation requirements
5-10% CO2
ZOI size for (+) bacitracin sus
> 10mm
Bile Esculin Test for what?
differentiate enterococci and group D streptococci,
inhibitory agent in bile esculin test
4% Bile salts
Gram-positive bacteria other than some streptococci and enterococci are inhibited by the bile salts in this medium. Organisms capable of growth in the presence of 4% bile and able to hydrolyze esculin to esculetin.
Esculetin reacts with Fe3+ and forms a dark brown to black precipitate.
Esculetin reacts with ____ and forms a dark brown to black precipitate.
Fe3+
(+): Enterococcus faecalis
(-): Streptococcus pyogenes
catalase can what?
degrade hydrogen peroxide to water and oxygen
coagulase will react directly with??
fibrinogen
Side note:
The clotting mechanism involves activation of a plasma coagulase-reacting factor (CRF), which is a modified or derived thrombin molecule, to form a coagulase-CRF complex. This complex in turn reacts with fibrinogen to produce the fibrin clot
muah
tube coagulase test
-incubate for how long?
35-37c in ambient air for 4hrs
the degradation product from metabolism of TRYPTOPHAN
Indole
Indole test medium
Tryptophan test medium
indole test reagent?
observe for red color after adding
Kovac’s reagent containing
p-dimethylaminobenzaldehyde
dim-ethyl-amino-benzal-dehyde
positive for indole?
Pink to wine-colored ring
negative: no color change
Bacteria (+) and (-) for indole
(+): E. coli
(-): Klebsiella pneumoniae
test to observe mixed acid fermentation route
Methyl Red Test
MR pH acid color breakpoint?
(+) pH: 4.4 = bright red color
weakly (+): Red-orange color
(-): Yellow colorn
VP test detects the formation of ?
acethyl methyl carbinol (ACETOIN)
as a product of glucose fermentation
Side note:
Acetoin is formed as a product of an alternative pathway of glucose fermentation utilized by some species of Enterobacteriacee.
Magandang gabi, baby.
VP reagents
6-8 drops of 5% alpha napthol
4 drops of 40% potassium hydroxide
Bacteria
VP pos and neg
Pos: K. pneumoniae
Neg: e coli
citrate test postive color indicator?
Bromthymol blue — from green to blue
Bacteria:
Citrate pos and neg
Pos: Enterobacter aerogenes
Neg: E. coli
The only members of enterobacteriaceae that are deaminase positive?
PPM
-proteus
-providencia
-morganella
LIA useful for identification of what bacterias?
SPPM
-Salmonella
-Proteus
-Providencia
-Morganella
when is cadaverine formed?
When the organism produces lysine decarboxylase
what forms the burgundy color on the slant of LIA?
2pts
- ferric ammonium citrate
- flavin mononucleotide
pH indicator of LIA
bromocresol purple
yellow at or below pH 5.2
purple above pH 6.8
Interpret the results LIA:
K/K
K/A
R/A
K/K - lysine decarboxylation (cadaverine is formed)
K/A -glucose fermentation
R/A - lysine deamination
side note:
Sodium thiosulfate in the presence of Ferric ammonium citrate will produce black precipitates
magandang gabi, baby.
motility semi-solid agar concentration?
0.4% or less to permit the organism to spread freely.
side note:
a. Alkaline slant and butt: H2S positive: Citrobacter freundi
b. Alkaline slant and butt: Escherichia coli
c. Alkaline slant and butt: H25 positive: Salmonella typhimurium
d. Red slant, acid butt: Proteus mirabilis
~
optochin interferes with??
ATPase and the production of ATP
TaxoP ZOI mm susceptible on sheep blood agar
14-16 mm
interpret the results TaxoP
- 17mm
- 13 mm
- sus
- resistant
test to differentiate members of enterobacteriaceae from other gram neg-rods.
TSI
TSI pH indicator
Phenol Red
serves as the indicators of acidification and H2S production of in TSI
(2)
- phenol red
- ferrous sulfate
test medium for salt tolerance test
-indicators or acid prodcution
heart infusion broth with 6.5% NaCl
-glucose and bromocresol purple
(+)
(-)
for salt tolerance test
(+) Visible turbidity in the broth, with or without a color change from purple to yellow.
(-) No turbidity and no color change (yellow color)
medium for urea test
results:
pos
neg
Christensen urea medium / urea test broth
(+) Change in color of slant or throughout the medium from light orange to magenta or pink
(-) No color change (agar slant and butt or broth remain light orange)
