Diverse potential of beta-lactamase inhibitors to induce class I enzymes.

The ability of various beta-lactamase inhibitors to induce class I beta-lactamases was assessed. Clavulanate was the most active compound, inducing Morganella morganii, Aeromonas caviae, and Enterobacter aerogenes over a broad concentration range and Citrobacter freundii, Pseudomonas aeruginosa, and Serratia marcescens at high concentrations. Disk approximation tests paralleled these results, with clavulanate, but not sulbactam or tazobactam, antagonizing the activity of several beta-lactams against these organisms.