Enterics Bench

Question 1

the approach to isolation an ID of Enterobacteriaceae is dependent on type of specimen to be examined:

Answer 1

• extraintestinal origin = urine, wound swabs, etc.; any member of Enterics may be significant and all organisms should be isolated + identified
• fecal = examined specifically for enteric pathogens using enteric screening media and biochemical tests

Question 2

Enterobacteriaceae pathogens

Answer 2

Salmonella
Shigella
Yersinia 
Plesiomonas
STEC (including O157:H7)

ALSO screen for:
Campylobacter
Vibrio
Aeromonas

Question 3

Acute gatrointestinal disease

Answer 3

• food intoxication

S. aureus, B. cereus, C. perfringens

Question 4

Reagent for:

a) Kovac’s indole
b) spot indole

Answer 4

a) paradimethylaminobenzaldehyde (cherry red)

b) p-dimethylaminocinnamaldehyde (blue/green)

Question 5

Aerosporin

Answer 5

polymyxin

inhibits gram neg b

Question 6

PEA

Answer 6

• phenylethyl alcohol
  used more for anaerobes; B. fragilis grows
  inhibits facultative anaerobic gnbs
  gram pos grows

Question 7

CNA

Answer 7

• colistin naladixic acid

- active against gnbs; isolate gpc