Polymyxin B and rifampin: new regimen for multiresistant Serratia marcescens infections.

Polymyxin B and rifampin were given to 12 patients with multi-drug-resistant nosocomial Serratia marcescens infections. Eight cures were achieved; drug hepatotoxicity occurred once; one fatal suprainfection was encountered; and two patients died during therapy of causes related to severe underlying illnesses. Polymyxin B and rifampin were uniformly synergistic in vitro against the infecting strains and against 40 additional clinical isolates of S. marcescens.