In vitro activity of temocillin, moxalactam and cefotaxime against gram negative bacteria sensitive or resistant to ureidopenicillins and/or cefacedone.

Minimal inhibitory concentrations (MIC's) of temocillin, cefotaxime and moxalactam were determined by agar dilution technique for 225 strains belonging to various species of Enterobacteriaceae and for 58 strains of H. influenzae and H. parainfluenzae. For Enterobacteriaceae, the MIC's of temocillin are distinctly higher than that of cefotaxime and moxalactam. But temocillin activity was not affected by resistance against ureidopenicillins and/or cefacedone. No resistant strains were encountered among E. coli, K. pneumoniae, Proteus spp. except one strain of P. vulgaris. In E. cloacae- strains with resistance against cefotaxime, temocillin was more active than moxalactam. S. marcescens- strains with a high MIC of temocillin were sensitive to cefotaxime and moxalactam. Temocillin is of the same order of activity as ampicillin against ampicillin-sensitive strains of H. influenzae and H. parainfluenzae. Its MIC is not influenced by beta-lactamases of these species.