CP-45,899 {3,3-dimethyl-7-oxo-4-thia-1-azabicyclo(3.2.0)heptane-2-carboxylic acid, 4,4-dioxide, [2S-(2a,5a)]} is an irreversible inhibitor of several bacterial penicillinases and cephalosporinases. In the presence oflow concentrations of CP45,899, ampicillin and other f,-lactams readily inhibit the growth of a variety of resistant bacteria that contain ,-lactamases. CP-45,899 used alone display...
