Gram Negative: Enteric - Enterobacteriaceae

Question 1

All are part of normal flora except

Answer 1

SSY

• Shigella
• Salmonella
• Yersinia

meaning dli opportunistic but pathogenic

Question 2

T/F:

I. toxins of family enterobacteriaceae are endotoxins
II. E. coli is the only pathogen capable of secreting both endotoxin and exotoxin

Answer 2

Both are TRUE

Question 3

Characteristics of Enterobacteriaceae family

Answer 3

• FA
• Cat (+)
• Oxidase (-)

Question 4

Salmonella spp. has how many serotypes

Answer 4

Salmonella: 1500
Escheria: 150

Question 5

Transport medium for Enterobactiaceae spp.

Answer 5

Carry-Blair medium

Question 6

H2S indicator in TSI

Answer 6

• Ferrous siulfate

Question 7

Sugars fermented in TSI

Answer 7

Glucose
Lactose
Sucrose

Question 8

Lactose fermenters:

Answer 8

LF-KEVEr

• Klebsiella
• Escherichia
• Vibrio
• Enterobacter

Question 9

Biochemical tests for Enterobacteriaceae

Answer 9

✓ TSI - PR
✓ Indole
- (+) control: E.coli
- (-) control: E. cloacae

✓ MR-VP
-ph for MR: 4.4
- Controls:
E.cloacae: MR (-) VP(+)
E.coli: MR (+) VP (-)

✓ Citrate utilization test (BTM blue)
- (+) control: K. pneumoniae – blue w/ growth
- (-) control: E.coli – no growth no color

Question 10

Indicator for Citrate utilization test

Answer 10

Bromothymol blue

Alkaline pH + BTM blue = Green -----> turquoise blue

Question 11

Infections occur due to hospital invasive procedures such as intravenous catheterization and urinary tract manipulations

Answer 11

Serratia marcesens

Question 12

Characteristics:
Proteus – Providencia – Morganella

Answer 12

Phenylalanine deaminase (+)
urease (+)

All are indole (+) except: P.mirabilis
H2S (+): Proteus
H2S (-): Providencia & Morganella