Staphylococcus aureus infection of dialysis shunt: absence of synergy with vancomycin and rifampin.

A 69-year-old man with chronic renal failure maintained on twice weekly hemodialysis had infection of the vascular access graft with bacteremia due to Staphylococcus aureus. Despite serum vancomycin levels that greatly exceeded the mean inhibitory and bactericidal concentrations, he failed to respond and rifampin was added. The bacteremia promptly cleared, but the patient died suddenly eight days later. Autopsy showed an acute arteritis of the graft with intracellular gram-positive organisms; two splenic blood cultures grew S aureus. Although previous investigators have shown that the combination of vancomycin and rifampin may be effective in some cases of S aureus endocarditis this antibiotic combination should not be used routinely unless in vitro synergy is demonstrated.