Enterococcus faecium is characteristically

Enterococcus faecium is characteristically

• A. Inhibited by the presence of bile in culture media
• B. Able to grow in the presence of high concentrations of salt
• C. L-pyrolidonyl-α-naphthylamide (PYR) negative
• D. Beta-hemolytic

Answer: (B)

The key trait being tested is salt tolerance. Enterococcus faecium, like other enterococci, can grow in high salt concentrations such as 6.5% NaCl. This ability is a classic differential feature used in labs to distinguish enterococci from many other streptococci, which are inhibited by such saline conditions. Therefore, the statement that Enterococcus faecium is able to grow in the presence of high concentrations of salt best captures its characteristic behavior. For context, enterococci are also known to tolerate bile and hydrolyze esculin, and they are typically PYR positive, not negative, and they are not reliably beta-hemolytic (they are often non-hemolytic or alpha). These additional traits help confirm identification, but the high-salt growth capability is the most distinctive and defining feature among the choices.

The key trait being tested is salt tolerance. Enterococcus faecium, like other enterococci, can grow in high salt concentrations such as 6.5% NaCl. This ability is a classic differential feature used in labs to distinguish enterococci from many other streptococci, which are inhibited by such saline conditions. Therefore, the statement that Enterococcus faecium is able to grow in the presence of high concentrations of salt best captures its characteristic behavior.

For context, enterococci are also known to tolerate bile and hydrolyze esculin, and they are typically PYR positive, not negative, and they are not reliably beta-hemolytic (they are often non-hemolytic or alpha). These additional traits help confirm identification, but the high-salt growth capability is the most distinctive and defining feature among the choices.