Nocardicin A, a new monocyclic beta-lactam antibiotic V. In vivo evaluation.

Nocardicin A is a new monocyclic beta-lactam antibiotic which provides a potent therapeutic effect in mice experimentally infected with gram-negative bacilli. When given subcutaneously to mice, the therapeutic effect of the drug was stronger than had been anticipated from in vitro studies. Nocardicin A was more potent in therapeutic effect than carbenicillin against infections due to Pseudomonas aeruginosa, Proteus mirabilis, Pr. vulgaris, Pr. rettgeri and Pr. inconstans, and was similar in effect to carbenicillin against infections due to Escherichia coli in mice. In addition, nocardicin A proved to be active against infections due to Serratia marcescens and other organisms resistant to beta-lactam antibiotics. When nocardicin A was given subcutaneously to mice, blood and hepatic levels of the drug were higher than those of carbenicillin.