A plasmid-mediated beta-lactamase with carbapenem-hydrolyzing activity from Serratia marcescens.

Serratia marcescens W-313/pSW313 was isolated from a clinical specimen that showed resistance to various beta-lactams. beta-Lactamase from this strain hydrolyzed oxyiminocephalosporins and carbapenems, but did not hydrolyze 2-carboxypenam and aztreonam. The kinetic parameters of this enzyme were similar to those of the carbapenem-hydrolyzing beta-lactamases mediated by R-plasmid from Pseudomonas aeruginosa and S. marcescens, whose properties were previously reported.