Type I beta-lactamases of Enterobacter cloacae and resistance to beta-lactam antibiotics.

The interaction of type-I beta-lactamases from Enterobacter cloacae with diverse beta-lactam compounds was examined. The ability of penicillin and cefoxitin to induce beta-lactamase production in this strain was assessed. The effect of beta-lactamase inhibitors was measured on beta-lactamase extracts and on intact cells. E. cloacae 78 strain is a stably derepressed mutant showing limited susceptibility to a number of antibiotics except imipenem. Imipenem would therefore be the appropriate choice for therapy of infections caused by stably derepressed mutants of Enterobacter sp. producing type-I beta-lactamases.