Which enzyme is produced by Staphylococcus aureus and aids in its identification?

Which enzyme is produced by Staphylococcus aureus and aids in its identification?

• A. Urease production
• B. Coagulase production
• C. Amylase production
• D. Lipase production

Answer: (B)

The key idea is using a virulence enzyme that sets Staphylococcus aureus apart from other staphylococci: coagulase production. S. aureus typically makes coagulase, which converts fibrinogen in blood into fibrin and causes clot formation. In the lab, a positive coagulase test (either the slide test for bound coagulase or the tube test for free coagulase) supports identification of S. aureus, while coagulase-negative staphylococci do not produce this enzyme and yield a negative result. This test is a classic distinguishing step because coagulase presence is strongly associated with S. aureus among clinically relevant Staphylococcus species. Other listed enzymes (urease, amylase, lipase) are not reliable or specific identifiers for S. aureus and don’t differentiate it from related species.

The key idea is using a virulence enzyme that sets Staphylococcus aureus apart from other staphylococci: coagulase production. S. aureus typically makes coagulase, which converts fibrinogen in blood into fibrin and causes clot formation. In the lab, a positive coagulase test (either the slide test for bound coagulase or the tube test for free coagulase) supports identification of S. aureus, while coagulase-negative staphylococci do not produce this enzyme and yield a negative result. This test is a classic distinguishing step because coagulase presence is strongly associated with S. aureus among clinically relevant Staphylococcus species. Other listed enzymes (urease, amylase, lipase) are not reliable or specific identifiers for S. aureus and don’t differentiate it from related species.