Sensitive and Specific Phenotypic Assay for Metallo-β-Lactamase Detection in Enterobacteria by Use of a Moxalactam Disk Supplemented with EDTA

Moxalactam is highly hydrolyzed by plasmid-mediated metallo-beta-lactamases (MBLs), whereas it is poorly inactivated by serine-active carbapenemases. This study demonstrated that moxalactam resistance constituted an effective screen for MBL expression in enterobacteria, which could be confirmed, even in low-MBL-producing isolates, by a disk potentiation test using moxalactam and EDTA.