E. coli 0157:H7 produces clear colonies on MacConkey agar, while common strains of the organism produce pink colonies on this medium. The organism stains pink in the Gram stain. Select the True statement, given this information.
A) E. coli 0157:H7 is Gram-positive AND is a normal constituent of the intestinal tract.
B) E. coli 0157:H7 is a normal constituent of the intestinal tract AND does not ferment sorbitol.
C) E. coli 0157:H7 does not ferment sorbitol AND is Gram negative.
D) E. coli 0157:H7 does not ferment sorbitol AND is Gram-positive.
E) E. coli 0157:H7 produces a toxin AND is a normal constituent of the intestinal tract.

Question

E. coli 0157:H7 produces clear colonies on MacConkey agar, while common strains of the organism produce pink colonies on this medium. The organism stains pink in the Gram stain. Select the True statement, given this information.
A) E. coli 0157:H7 is Gram-positive AND is a normal constituent of the intestinal tract.
B) E. coli 0157:H7 is a normal constituent of the intestinal tract AND does not ferment sorbitol.
C) E. coli 0157:H7 does not ferment sorbitol AND is Gram negative.
D) E. coli 0157:H7 does not ferment sorbitol AND is Gram-positive.
E) E. coli 0157:H7 produces a toxin AND is a normal constituent of the intestinal tract.

Quizplus · Accepted Answer

E. coli O157:H7 does not ferment sorbitol, which is why it produces clear colonies on MacConkey agar, unlike common E. coli strains that ferment sorbitol and produce pink colonies. It stains pink in the Gram stain, indicating it is Gram-negative.

E Coli 0157:H7 Produces Clear Colonies on MacConkey Agar, While