Question

1. which pair of bacteria can be differentiated by oxidase test?
A. Pseudomonas and E. coli
B. Salmonella and Proteus
C. Proteus and E. coli
D. Shigella and Salmonella

2. Colonies of which color would you expect on HE agar if shigellosis is suspected?
A. Pink
B. Red with black center
C. Red without black center
D. Green with black center
E. Green without black center

3. Colonies of which color would you expect on HE agar if Enterococcus sp. is suspected?
A. Pink
B. Salmon/orange
C. Red with black centers
D. Green with black centers
E. None of the above

Answer 1

Answer:

1. A. Pseudomonas and E. coli

2. B. Red without black center

3. B. Salmon/orange

Explanation:

Pseudomonas is referred to as an oxidase positive bacteria while E. Coli is an oxidase negative bacteria. The use of the oxidase test will be helpful in the differentiation of the two Bacteria according to their oxidase activity/properties.

Colonies of Red without black center color is what is expected on HE agar if shigellosis is suspected.

Colonies of Salmon/Orange color is what is expected on HE agar if Enterococcus sp. is suspected.