Nonspecific Induction of -lactamase in Enterobacter cloacae

Abstract

Induction of .beta.-lactamase was monitored in a strain of E. cloacae exhibiting high resistance to most .beta.-lactam antibiotics. Large amounts of the enzyme were induced not only in the presence of .beta.-lactams, but also in the presence of other bicyclic molecules such as folic acid, thiamine, tryptophan or hemin. Complex media (such as Trypticase soy broth and Schaedler''s broth) and various body fluids (serum, pleural fluid and CSF) also possessed considerable induction potency. Neither specific induction (by .beta.-lactams) nor nonspecific induction (by other bicyclic compounds) could be augmented by addition of exogenous cAMP. Inducible .beta.-lactamases deserve more attention, above all with respect to the development of resistance against 3rd-generation cephalosporins.