Identification and clinical isolates of metallo-beta-lactamases producing Pseudomonas aeruginosa clinical isolates in university hospital from Zanjan province, Iran

ABSTRACT

Infectious by Pseudomonas aeruginosa has spread worldwide and metallo-beta-lactamases [MBL] are being reported with increasing frequency. The aim of this study was to investigate the antibiotic susceptibility and distribution of bla[VIM] and bla[IMP] genes in P. aeruginosa isolates from Zanjan Province of Iran. A total of 70 P. aeruginosa isolates were identified from patients admitted at intensive care units. The antimicrobial susceptibility was tested by disk diffusion [Kirby-Bauer] method and for production of MBL using double-disk synergy test [DDST]. After DNA extraction, the presence of bla[VIM] and bla[IMP] genes and class 1 integron were detected by PCR. Most of the isolates were resistant to meropenem, cefotaxime and imipenem [IPM]. Also, 44/70 [62.85%] IPM resistant isolates were confirmed by DDST. Of the 44 clinical isolates, 41 [93%] isolates showed MIC >/= 4 micro g/ml for IPM. Based on the DDST results, 36 [87.8%] were confirmed to be MBL producers. PCR amplification showed that 23/41 [56%] carried bla[VIM] and 10/41 [24.3%] possessed bla[IMP] gene. Also, 31/44 [70.5%] isolates contained class 1 integron gene. Our results highlight that the genes for Verona integron-encoded metallo- beta -lactamase, IPM beta -lactamases and class 1 integrons were predominantly present among the IPM-resistant P. aeruginosa tested in our province and also the frequency of bla[VIM] type is higher than bla[IMP]. This is the first report of P. aeruginosa strains producing blaIMP with high frequency from Zanjan province of Iran