The in vitro activity and beta-lactamase stability of cefpiramide compared with other beta-lactam antibiotics.

The in vitro activity of cefpiramide, a new ureido cephalosporin antibiotic, was determined against 1128 gram-positive and gram-negative aerobic and anaerobic bacteria selected for resistance to ampicillin and cefazolin. Cefpiramide was less active on a milligram basis than cefotaxime, ceftazidime, moxalactam, and aztreonam against all of the members of the Enterobacteriaceae. Cefpiramide inhibited many Pseudomonas aeruginosa resistant to carbenicillin, piperacillin, and cefotaxime, but it was less active than ceftazidime and cefsulodin. Cefpiramide inhibited staphylococci and streptococci and had appreciable activity against Streptococcus faecalis and Listeria moncytogenes. It had less activity than cefoxitin against anaerobic species. Cefpiramide inhibited permeability mutants of Escherichia coli at lower concentrations than the parent strain, suggesting an effect of entry upon its activity. Although cefpiramide was resistant to attack by most chromosomal beta-lactamases, it was hydrolyzed by the common plasmid beta-lactamases TEM and SHV and by the chromosomal Proteus vulgaris, type Ic, cephalosporinase.