The new penicillinase-resistant semisynthetic penicillins methicillin and oxacillin have proved effective against staphylococci in vitro and in vivo. They are considered the answer to the staphylococcal problem. It has been observed that the antibacterial activity of the new penicillins is much inferior to that of benzylpenicillin since a large number of bacteria survived despite their action.1-3,7
In using methicillin at first and oxacillin lately we have been struck by the slowness of response, especially of the septicemia and endocarditis patients. In the 2 representative cases that we describe here, Staphylococcus was isolated from the blood stream while the patients were under treatment with methicillin or oxacillin. A large number of survivors have been observed in in vitro experiments in high concentrations of the antibiotics.
Report of Cases
This patient was a 19-year-old male with a congenital aortic stenosis. Staphylococcal endocarditis was diagnosed in January, 1961. The fever
DAIKOS GK, KONTOMICHALOU P. Persistence of Staphylococcus to Methicillin and Oxacillin: Observations on Two Cases of Endocarditis. Arch Intern Med. 1963;111(6):719–724. doi:10.1001/archinte.1963.03620300039007
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