Diversity and Variation Question 8

Methicillin-resistant Staphylococcus aureus (MRSA) can be a serious threat to human health. There is evidence that S. aureus infections are common in hospitals and that MRSA have become resistant to other antibiotics besides methicillin. This suggests that the rapid evolution of resistance in the bacteria poses a serious public-health challenge. Which of the following best explains the ability of MRSA to evade existing drug therapies?

MRSA have very long generation times and very large population sizes.

MRSA develop new alleles by intentionally introducing specific mutations that will give them a selective advantage over other bacteria.

MRSA metabolize many drugs in their lysosomes and therefore evolve resistance at a high rate.

MRSA exchange genetic material with other antibiotic-resistant bacteria, which can spread resistance in the S. aureus population.