Identification of Staphylococcus aureus

In accordance with Clinical Laboratory Standards Institute guidelines (CLSI) (10), clinical specimens were inoculated onto the blood agar base (Oxoid, Basingstoke, Hampshire, England) to which 5% sheep blood was added and mannitol salt agar (Oxoid, Basingstoke, Hampshire, England) by using the streaking method. Inoculated plates were incubated at 35–37°C for 18 to 24 hrs aerobically. Bacterial colonies showing typical characteristics of S. aureus (i.e., beta-hemolytic on blood agar and colonies with golden yellow pigmentation on mannitol salt agar) were subjected to subculture onto basic media, Gram stain, catalase, coagulase, and Pastorex staph extract. These catalase, coagulase, Pastorex, and Gram-positive bacteria appearing in grape-like clusters were considered as S. aureus [8 (link), 10 ].