Over the past several years, methicillin-resistant Staphylococcus aureus (MRSA) has become infamous as the cause of skin infections among football players, wrestlers, fencers, and other athletes who share equipment or engage in contact sports. MRSA strains are resistant to many drugs, including methicillin, a penicillin derivative commonly used to treat staphylococcal infections. Gram staining of samples taken from the cutaneous pustules of the caretakers and the calf in this case would have revealed the presence of:.