Isolation and assessment of phenotypic and genotypic characteristics of metallo-β-lactamase genes in Pseudomonas aueroginosa strains isolated from clinical samples at Vali-e-Asr Hospital in Zanjan province

Infections caused by Pseudomonas aeruginosa and dissemination of metallo-beta-lactamases (MBL) have been reported with increasing frequency through-out the world. The aim of this study was to investigate the antibiotic susceptibility and identification of blaVIM and blaIMP genes in P. aeruginosa isolates in Zanjan Province. A total of 70 P. aeruginosa isolates were identified from the patients at intensive care units (ICU) in Zanjan Province. The antimicrobial susceptibility was tested by disk diffusion (Kirby-Bauer) method and MBL producing strains were identified by double-disk synergy test (DDST). From genotypical point of view the presence of blaVIM and blaIMP genes and class 1 integron was confirmed by PCR. Of 70 strains of P. aeruginosa detected by phenotypic method، the highest rate of resistance was found in the following order: meropenem، cefotaxime and ceftazidime، imepenem gentamicin، piperacillin، and ciprofloxacin. DDS test showed that of 44 resistant isolates to imepenem 36 (81. 8%) were MBL producing. We found 33 MBL producing strains by PCR، 23 isolates had VIM gene (52. 2%) and 10 isolates carried IMP gene (22. 3%). The IMP gene in 8 of the 10 isolates was IMP1 (18. 2%). Of 44 resistant strains to imepenem only 31 isolates (70. 5%) had class 1 integron gene. Our results showed that prevalence of antibiotic resistance due to MBL production in our province is on the rise and among the MBL producing strains the frequency of VIM genes is higher than IMP genes.