Cefotetan: antimicrobial activity in-vitro compared with that of cefotaxime

The antimicrobial activity of cefotetan and cefotaxime were compared in vitro against 547 strains of aerobes and 24 strains of Bacteroides fragilis. The strains were recent clinical isolates from 20 hospitals. Cefotetan was found to exhibit an activity two- to fourfold lower than that of cefotaxime against most of the enterobacteriaceae. About half the number of Enterobacter aerogenes and Enterobacter cloacae strains resistant to cefotetan were resistant also to cefotaxime. Cefotetan was more active than cefotaxime against most of the strains of Proteus vulgaris. In contrast to cefotaxime which was moderately active, cefotetan was inactive against Pseudomonas aeruginosa. Cefotetan had limited activity against Staphylococcus aureus and Streptococcus faecalis was resistant to both cefotetan and cefotaxime. Bact. fragilis was inhibited more effectively by cefotetan than by cefotaxime. Depending on the species tested, the activity of cefotetan was influenced significantly by the inoculum size in some cases. Different test media did not affect the results.