S. aureus causes a wide variety of infections, ranging from wound infection to pneumonia. Treatment of S. aureus infection with penicillin is often complicated by the

Staphylococci are Gram-positive, non-sporeforming cocci. Clinically, their antibiotic resistance poses major problems. Many strains produce 13-lactamase (penicillinase), an enzyme that destroys penicillin by opening the lactam ring. Drug resistance, mediated by plasmids, may be transferred by transduction.