Susceptibility of 50 isolates of Clostridium perfringens to cefotaxime, fosfomycin, penicillin G and vancomycin; variable tolerance for vancomycin.

50 strains of Clostridium perfringens recovered from human fecal specimens were examined for susceptibility to cefotaxime (CTX), fosfomycin (Fosfo), penicillin G (Pen G) and vancomycin (Vanco) with the aid of a microtiter procedure. The geometric mean minimal inhibitory concentrations (MICs) of CTX, Fosfo, Pen G and Vanco were 0.81, 48.3, 0.15 and 0.33 micrograms/ml, respectively; the geometric mean bactericidal concentrations (MBCs) of the four drugs were 1.25, 109.8, 0.53 and 9.05 micrograms/ml, respectively. The geometric mean MBC:MIC ratios of CTX, Fosfo, Pen G and Vanco amounted to 1.56, 1.97, 3.64 and 27.0. It was concluded that the C. perfringens strains were not tolerant for CTX, Fosfo and Pen G; however, the strains displayed variable tolerance for Vanco.