Cefamandole, a Cephalosporin Antibiotic with an Unusually Wide Spectrum of Activity

Abstract

The in vitro activity of cefamandole, 7- d -mandelamido-3-(1 methyl-1H-tetrazol-5 yethiomethyl)-3-cephem-4 carboxylic acid, was investigated. The majority of streptococci and pneumococci were inhibited by 0.1 μg/ml. Activity against Staphylococcus aureus was below that of cephalothin, but most strains were inhibited by 0.4 μg/ml. Enterococci were not inhibited by less than 25 μg/ml. Cefamandole was very active against most members of the Enterobacteriaceae , with 70% of Escherichia coli , 86% of Klebsiella pneumoniae , and 88% of Proteus mirabilis inhibited by 1.6 μg/ml. A number of Enterobacter aerogenes, Proteus vulgaris , and Serratia marcescens strains were inhibited by less than 25 μg/ml. Pseudomonas species were resistant. Cefamandole was more active than cephalothin, cephaloridine, or cephalexin against members of the Enterobacteriaceae . Inoculum size and type of medium had variable effects on the minimal inhibitory concentration, depending upon the particular strain tested. Strains of Enterobacter, Serratia , indole-positive Proteus species showed the greatest inoculum effect. Similarly, these species showed a several-fold difference of bactericidal and inhibitory levels. Resistance of cefamandole to hydrolysis by gram-negative beta-lactamase played a partial role in its activity, but some strains that hydrolyzed the agent were susceptible.