Within six months of effectively using methicillin to treat S. aureus infections in a community, all new S. aureus infections were caused by MRSA. How can this best be explained? a. A patient must have become infected with MRSA from another community. b. In response to the drug, S. aureus began making drug- resistant versions of the protein targeted by the drug. c. Some drug-resistant bacteria were present at the start of treatment, and natural selection increased their frequency. d. S. aureus evolved to resist vaccines.

Video transcript

Hello everyone here We have a question telling us. S. Aureus diagnosis were brought on by Mersa six months after methicillin was successfully used to treat S. Aureus outbreaks in the community. What is the easiest way to understand this? A. The vaccine news contains a stronger strain of bacteria. B some s aureus bacteria were able to survive and have evolved to a more resistant type. See another source of infection had sprung or deed. The vaccine was not able to identify target species. So the easiest way to understand this is that some s aureus bacteria were able to survive and had evolved to a more resistance hype because the vaccine did not completely eliminate the bacteria so the bacteria that survived was able to evolve. So our answer here is B. Thank you for watching. Bye.