Within Six Months of Effectively Using Methicillin to Treat S

question 4

Multiple Choice

Within six months of effectively using methicillin to treat S. aureus infections in a community, all new infections were caused by MRSA. How can this result best be explained?

• A) S. aureus can resist vaccines.
• B) A patient must have become infected with MRSA from another community.
• C) In response to the drug, S. aureus began making drug-resistant versions of the protein targeted by the drug.
• D) Some drug-resistant bacteria were present at the start of treatment, and natural selection increased their frequency.
• E) The drug caused the S. aureus DNA to change.

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Definitions:

Intercept

The value where a line crosses the y-axis in a graph.

Predicted GPA

An estimation of a student's grade point average based on variables or predictors such as study habits, high school GPA, and standardized test scores.

Slope

A measure of the steepness or incline of a line, calculated as the ratio of the vertical change to the horizontal change between two points on the line.

Intercept

In linear regression, it is the expected value of the dependent variable when all independent variables are zero.