In vitro activity of new cephalosporins against multi-resistant gram-negative bacteria.

The in vitro sensitivities of 47 multi-resistant gram-negative bacilli against six third generation cephalosporins were investigated. Overall, moxalactam was the most active compound and cefoperazone the least active. Ceftizoxime and ceftazidime were very active against Enterobacteriaceae. Ceftriaxone and ceftizoxime were active against Escherichia coli and Klebsiella spp., but were inactive against Pseudomonas spp.; Achromobacter sp. was resistant to all drugs, while Citrobacter freundii was sensitive to every antibiotic tested. These drugs may be clinically useful in infections with multi-resistant gram-negative bacteria.