In 1980, only 1 to 5% of all Staphylococcus aureus isolates were MRSA strains. Now 60 to 70% of S. aureus isolates are MRSA strains. What process is the cause of this situation?
A) stabilizing selection of humans
B) directional selection of humans
C) directional selection of bacteria
D) diversifying selection of bacteria

Question

Quizplus · Accepted Answer

The increase in MRSA strains suggests that directional selection is occurring among the bacteria, favoring the prevalence of MRSA. This could be due to increased antibiotic use, which selects for bacteria with antibiotic resistance genes. There is no evidence to suggest that stabilizing or diversifying selection of bacteria is occurring, and selection of humans is not directly related to the increase in MRSA strains.

In 1980, Only 1 to 5% of All Staphylococcus Aureus