Prevalence of blaIMP and blaVIM gene carriage in metallo-β–lactamase-producing burn isolates of Pseudomonas aeruginosa in Tehran

Background/aim: To study the prevalence of blaVIM and blaIMP genes in metallo-β-lactamase (MBL)–producing burn isolates of Pseudomonas aeruginosa in relation with AmpC and extended-spectrum β-lactamase (ESBL) production. Materials and methods: Thirty-two carbapenem-resistant MBL-producing P. aeruginosa burn isolates from Shahid Motahari Burn Hospital in Tehran were employed. Antibiotic susceptibility was determined to 13 antibiotics including imipenem and meropenem by disk diffusion. AmpC and ESBL production was detected by the AmpC disk test and combined disk diffusion assay, respectively. blaIMP and blaVIM gene carriage was shown by polymerase chain reaction and type-specific primers. Results: AmpC production was observed in 81% and ESBL production was detected in 12.5% of the isolates. blaIMP carriage was observed in 56.25% and blaVIM gene in 46.8% of the isolates. Surprisingly, 43.5% of the isolates carried both blaIMP and blaVIM genes. Conclusion: We think that this is the first report on the cocarriage of blaIMP and blaVIM in P. aeruginosa. There was also a strong association between MBL gene carriage and AmpC β-lactamase production.