Emergence of metallo-β-lactamase IMP-14 and VIM-2 in Pseudomonas aeruginosa clinical isolates from a tertiary-level hospital in Thailand

Seventy-five clinical isolates of Pseudomonas aeruginosa collected in a tertiary teaching hospital in Thailand were investigated for susceptibility to antimicrobials including imipenem. Metallo-beta-lactamase (MBL) enzymes were detected by E-test MBL assay and PCR; class 1 integron genes were also detected by PCR. Strains positive for bla(IMP) and bla(VIM) genes were further characterized by DNA sequencing and examined for clonality by pulsed-field gel electrophoresis. High rates of resistance to anti-pseudomonal agents were found. MBL enzymes were found in 13 (17.3%) strains and 24 (32%) carried class 1 integron genes. Twelve of the latter strains harboured the bla(IMP-14) gene and one strain the bla(VIM)-(2) gene. All of the IMP-14 strains were identical or closely related suggesting clonal dissemination of these genes.