The in vitro activity of 15 penicillins and mecillinam against Neisseria gonorrhoeae

Abstract

Minimum inhibitory concentrations (MIC's) of 15 penicillins and mecillinam were determined on solid media for 92 strains of Neisseria gonorrhoeae. Regression lines for MIC's of each antibiotic against those of benzylpenicillin were calculated. The order of activity against benzylpenicillin-insensitive strains was ampicillin, amoxycillin, azidocillin, ticarcillin carbenicillin, sulfocillin, phenoxymethylpenicillin, methicillin, phenethicillin, mecillinam, propicillin, flucloxacillin, nafcillin, cloxacillin and dicloxacillin. The regressions for flucloxacillin, cloxacillin and dicloxacillin were indistinguishable as were those of azidocillin, ticarcillin and carbenicillin. Only ampicillin and amoxycillin showed greater activity than benzyl-penicillin against relatively resistant strains.