Oxacillin, a derivative of methicillin, was first synthesized in the early 1960s as part of a research initiative led by Peter Doyle and John Naylor of Beecham, in consort with Bristol-Myers. Members of the isoxazolyl penicillin family, which includes cloxacillin, dicloxacillin, and oxacillin, were synthesized to counter the increasing prevalence of infections caused by penicillin-resistant Staphylococcus aureus. While methicillin could only be administered via injection, the isoxazolyl penicillins, including oxacillin, could be given orally or by injection. Following the synthesis of cloxacillin and oxacillin, Beecham retained the right to commercially develop cloxacillin in the United Kingdom while Bristol-Myers was given the marketing rights for oxacillin in the United States.