Enterococcus faecium is typically PYR positive and usually nonhemolytic.

Enterococcus faecium is typically PYR positive and usually nonhemolytic.

• A. PYR positive and nonhemolytic
• B. PYR negative and nonhemolytic
• C. PYR positive and beta-hemolytic
• D. PYR negative and beta-hemolytic

Answer: (A)

The main idea is using a combination of a biochemical test result and a colony appearance on blood agar to identify Enterococcus species. Enterococcus faecium typically tests positive for PYR because it has the enzyme pyrrolidonyl arylamidase. On blood agar, Enterococcus usually shows gamma-hemolysis, meaning there’s no hemolysis around the colonies. Put together, a PYR-positive result with nonhemolysis fits Enterococcus faecium well. While some strains can vary and show weak or unusual hemolysis, the common pattern you’re expected to know is PYR positive and nonhemolytic. If you saw PYR negative or beta-hemolysis, that would point away from Enterococcus and toward other organisms with different profiles.

The main idea is using a combination of a biochemical test result and a colony appearance on blood agar to identify Enterococcus species. Enterococcus faecium typically tests positive for PYR because it has the enzyme pyrrolidonyl arylamidase. On blood agar, Enterococcus usually shows gamma-hemolysis, meaning there’s no hemolysis around the colonies. Put together, a PYR-positive result with nonhemolysis fits Enterococcus faecium well. While some strains can vary and show weak or unusual hemolysis, the common pattern you’re expected to know is PYR positive and nonhemolytic. If you saw PYR negative or beta-hemolysis, that would point away from Enterococcus and toward other organisms with different profiles.