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

The interaction of type-I β-lactamases from Enterobacter cloacae with diverse β-lactam compounds was examined. The ability of penicillin and cefoxitin to induce β-lactamase production in this strain was assessed. The effect of β-lactamase inhibitors was measured on β-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 appropiate choice for therapy of infections caused by stably derepressed mutants of Enterobacter sp. producing type-I β-lactamases.