Therapeutic potential of rifampin in enterococcal infections.

Rifampin is active against enterococci in vitro; virtually all clinical isolates are inhibited by concentrations of less than or equal to 16 micrograms/ml. However, rifampin is bacteriostatic, not bactericidal, and resistance emerges rapidly when the drug is employed alone against enterococci in vitro. The combination of rifampin with beta-lactam drugs, aminoglycosides, or vancomycin generally gives indifferent results. Limited data from studies done in vivo are contradictory and do not document unequivocally that rifampin is strikingly active, even in combination with other agents, against enterococcal infections. Whether rifampin will ever play a role in therapy for enterococcal infections in humans remains to be determined.