Metallo-β-lactamase-producing Gram-negative bacilli in Korean Nationwide Surveillance of Antimicrobial Resistance group hospitals in 2003: Continued prevalence of VIM-producing pseudomonas spp. and increase of IMP-producing Acinetobacter spp

Metallo-β-lactamase (MBL)-producing Pseudomonas spp. and Acinetobacter spp. were prevalent in Korean hospitals. In this study, the prevalence and presence of MBL-producing isolates among imipenem-nonsusceptible and imipenem-susceptible isolates, respectively, were screened. The genetic and phenotypic characteristics of MBL-producing isolates were determined. Among imipenem-nonsusceptible isolates, 52 (11.1%) of 467 Pseudomonas spp. were bla VIM-like allele-positive, and 33 (15.1%) of 218 Acinetobacter spp. were either bla VIM- or bla IMP-like allele-positive. One bla VIM-like allele-positive isolate of Acinetobacter spp. was detected among 84 imipenem-susceptible Acinetobacter isolates. The minimum inhibitory concentration for 90% of isolates of imipenem was higher (> 128 μg/mL) for Pseudomonas spp. than Acinetobacter spp. (16 μg/mL), although both had bla VIM-like allele. The source of MBL-producing isolates was mostly the sputum and urine of patients in the intensive care unit. Pulsed-field gel electrophoresis analysis suggested the intra- and inter-hospital spread of MBL-producing strains at some hospitals. In conclusion, bla VIM-like allele-positive P. aeruginosa remained highly prevalent, and the proportion of bla IMP-like allele-positive Acinetobacter spp. has increased significantly in most Korean hospitals.