B

Dicloxacillin is a penicillinase-resistant penicillin and remains the drug of choice for infections caused by penicillinase-producing bacteria such as Staphylococcus aureus, whereas ampicillin is inactivated by the enzyme and erythromycin is only an alternative for penicillin-allergic patients [Gahrn-Hansen, 2002, PMID 12362608].