Beneficial effects of catalase or pyruvate in a most-probable-number technique for the detection of Staphylococcus aureus

The effects of the addition of catalase (EC 1.11.1.6) or pyruvate on the enumeration of Staphylococcus aureus in Trypticase soy broth with 10% NaCl were examined using a most-probable-number technique. Addition of catalase or pyruvate to the broth increased enumeration of all heat-stressed S. aureus strains tested. Increases were also observed with nonstressed cells. Catalase and pyruvate were similarly effective when added to Trypticase soy broth-10% NaCl in enumerating staphylococci naturally present in low-temperature-rendered ground-beef samples.