Activity and specific beta-lactamase susceptibility of cefoperazone and moxalactam. Comparison with other cephalosporins.

Comparison of the activity of cefoperazone, cefamandole, cefotaxime, cephalothin and moxalactam against Enterobacteriaceae showed cefoperazone to be twofold (Escherichia coli, Klebsiella) to eigthfold (Enterobacter) more active than cefamandole. The lowes MIC values were found for cefotaxime (0.03 - 0.25 microgram/ml) followed by moxalactam (0.06 - 0.25 microgram/ml). Cefoperazone stood out in activity against Pseudomonas aeruginosa (MIC50 4 microgram/ml). Cephalothin resistance affected the MIC values of cefoperazone and moxalactam only to a small degree. From beta-lactamase susceptibility studies it was concluded that cefoperazone may be hydrolyzed by TEM type beta-lactamases, but that the cephalosporinases (class I) and the chromosomal broad-spectrum beta-lactamases (class IV) only have little effect on this antibiotic. Moxalactam was not degraded by any of the beta-lactamase preparations tested.