ABSTRACT
Methicillin-resistant Staphylococcus aureus (MRSA) is defined by minimum inhibitory concentrations of methicillin of 16 mg/mL or more or oxacillin 4 mg/mL or more (1). Strains of MRSA possess the mecA gene (1,2). This chromosomal gene encodes an altered enzyme, termed penicillin-binding protein 2a (or PBP20), which has a low affinity for all beta-lactam antibiotics. As a rule, strains of MRSA also possess resistance determinants for many other antimicrobial agents.
