Role of Permeability in the Activities of β-Lactams against Gram-Negative Bacteria Which Produce a Group 3 β-Lactamase

Abstract

The production of a group 3 β-lactamase permittedEscherichia coli to raise the MICs of ceftazidime, cefpirome, and meropenem greatly but those of imipenem and piperacillin only slightly. The ratios of maximum rate of hydrolysis toK_m of ceftazidime, cefpirome, and piperacillin were lower than those of meropenem and imipenem for the group 3 β-lactamase. The permeability coefficients for piperacillin and meropenem were higher than those for ceftazidime and cefpirome. Imipenem had the highest permeability coefficient.