Laboratory Part, Exam # 2 Flashcards
What characteristic differentiates genus Proteus from all the other Enterobacteriaceae?
urease positive
When a bacteria is said to be positive for gelatin test, it contains gelatinase. What does gelatinase do?
hydrolyzes gelatin
A TSI tube was inoculated with isolated culture from MAC. It yielded K/A. What does this mean?
only glucose was fermented
A SIM tube was inoculated with isolated culture from MAC. The said tube was incubated. After incubation, it became turbid, with black color & it turned red during indole test. What does this mean?
motile
H2S producing
indole positive
In Indole test, what reagent is involved?
Ehrlich’s reagent
Citrobacter often tests positive for Simmons citrate agar. What color does it yield?
blue
Which is false?
A. To isolate Salmonella, selenite F broth is used.
B. To isolate Salmonella, MacConkey agar is used.
C. Both are false.
D. Both are true.
A
False about Salmonella A.Most are non-motile B. Non-lactose fermenter C. Most produce H2S (slight production only) D. Form acid in glucose and mannose
A
What sort of colony growth is observed in Salmonella-Shigella agar, when Salmonella is inoculated?
colorless colonies with black centers
XLD is one of the media used in Salmonella culture. What does XLD stand for?
Xylose Lysine Desoxycholate
To isolate Salmonella, what specimen is usually obtained?
feces or rectal swab
False about Shigella
a. non-lactose fermenting
b. non-motile
c. able to produce gas from glucose
d. none of the above
C
EMB may be used to culture Salmonella and Shigella. What does EMB stand for?
Eosin Methylene Blue
False about E.coli A. positive for indole, MR and VP B. negative for H2S, urease and citrate C. may be motile or non-motile D. ferments mannitol, glucose and lactose
A
negative for VP
Since E.coli ferments lactose, what sort of colonies does one expect to see on MAC?
dry, pink colonies