Question

A mixture of S. aureus and the enteric bacteria E. coli was placed onto the skin of the fingertips of a volunteer. The volunteer immediately touched one of their inoculated fingertips to nutrient agar plate #1 and then waited 30 minutes and touched a different inoculated finger to nutrient agar plate #2. After incubating the plates overnight, what pattern of growth would you expect to see on the plates?

A. Both E. coli and S. aureus grew on both plates.
B. Plate #1 grew both, while plate #2 grew only S. aureus.
C. Plate #1 grew both, while plate #2 grew only E. coli.
D. Plate #1 grew only S. aureus, while plate #2 grew both.
E. Plate #1 grew only E. coli, while plate #2 grew both.

Answer 1

Plate #1 would show growth of both S. aureus and E. coli, while Plate #2 would show growth of only S. aureus.

Step-by-step explanation:

Based on the information provided, we know that the volunteer touched fingers inoculated with both S. aureus (Staphylococcus aureus) and E. coli (Escherichia coli) to nutrient agar plates #1 and #2, respectively. After incubating overnight, the pattern of growth on Plate #1 would show growth of both S. aureus and E. coli, while Plate #2 would show growth of only S. aureus. This is because S. aureus is a Gram-positive bacterium that can grow on nutrient agar, whereas E. coli is a Gram-negative bacterium that may not grow well on nutrient agar.