Class 1 integron containing metallo β-lactamase gene blaIMP-1 in carbapenem-resistant Pseudomonas aeruginosa in Thailand

We investigated the genetic properties of two carbapenem-resistant Pseudomonas aeruginosa isolates collected from a regional hospital in the north of Thailand. Both isolates demonstrated high-level resistance to extended-spectrum cephalosporins and carbapenems. Detection of the MBL genes was positive for blaIMP in both isolates. Pulsed field gel electrophoresis (PFGE) analysis showed that the two P. aeruginosa isolates were nonclonal. Molecular analysis of the blaIMP in isolate 837 showed the presence of a blaIMP-1 gene inserted in a class 1 integron. The blaIMP-1 was plasmid-mediated according to the transformation assay. This is the first case of the blaIMP-1 gene in carbapenem-resistant P. aeruginosa in Thailand, suggesting the further dissemination of this gene in Southeast Asia.