Susceptibility of enterococci. II. Inhibitory and bactericidal activity of drugs in combination against Streptococcus faecalis and Streptococcus faecium.

The microbiological utility of antibiotic combinations against Streptococcus faecalis and Streptococcus faecium strains was studied. The drugs used were netilmicin + amoxicillin (20 strains); netilmicin + piperacillin (20 strains); netilmicin- + vancomycin (20 strains); netilmicin + rifampicin (20 strains). Netilmicin used in combination with the penicillins was advantageous against Streptococcus faecalis, but not uniformly against Streptococcus faecium. The combinations of netilmicin with vancomycin or rifampicin were no more effective than the single drugs in most cases, although the response varied for the different strains of the two species.