Imipenem-EDTA disk method for differentiation of metallo-β-lactamase-producing clinical isolates of Pseudomonas spp. and Acinetobacter spp.

Rapid detection of metallo-beta-lactamase (MBL)-producing gram-negative bacilli is necessary to prevent their dissemination. The method using a disk with imipenem plus 750 mug of EDTA differentiated all MBL-producing pseudomonads, and the sensitivity and specificity for acinetobacters were 95.7 and 91.0%, respectively. The imipenem-EDTA disks were stable for 12 and 16 weeks at 4 and -20degreesC, respectively.