Induction of cephalosporinase production by various penicillins in Enterobacteriaceae.

Abstract

The inducer activity of 7 penicillins for cephalosporinase (CSase) production and their antibacterial activity against CSase-producing strains were studied using clinical isolates of Proteus morganii, P. rettgeri, P. vulgaris, Enterobacter cloacae and Serratia marcescens. Piperacillin, apalcillin and methicillin showed rather low inducer activity for CSase production in all strains tested. Ampicillin, carbenicillin and sulbenicillin showed higher inducer activity for CSase production. Piperacillin, apalcillin and ampicillin were less stable to CSase than were carbenicillin, sulbenicillin and methicillin, but much more stable than benzylpenicillin. In the growing culture of CSase-producing strains, piperacillin and apalcillin were rather stable. Against CSase-producing strains, piperacillin and apalcillin were more active than other penicillins tested.