Interference of Aureomycin and of Terramycin with Action of Penicillin in Vitro . ∗

Summary

Aureomycin and terramycin interfered in vitro with the bactericidal action of penicillin against S. pyogenes and K. pneumoniae. The early bactericidal rate was slower with mixtures of aureomycin or terramycin with penicillin than with penicillin by itself. Ultimately, however, the mixtures were more likely to destroy all exposed bacteria than were the single antibiotics. Interference was most marked when bacteriostatic concentrations of aureomycin or terramycin were mixed with actively bactericidal concentrations of penicillin.