Clinical study of combination therapy with oxacillin and rifampin for staphylococcal infections.

In a prospective, randomized study of staphylococcal infections, 27 patients received oxacillin plus rifampin and 29 received oxacillin alone. Vancomycin was substituted for oxacillin when the pathogen was demonstrated to be resistant to oxacillin in vitro. Infection was cured in 18 (67%) of the 27 patients receiving oxacillin (or vancomycin) plus rifampin and in 12 (41%) of the 29 receiving oxacillin (or vancomycin) alone (P less than .01). The clinical effect of the addition of rifampin to oxacillin (or vancomycin) was beneficial in spite of a rifampin-associated reduction in the bactericidal activity of serum containing high concentrations of oxacillin.