detection of pseudomonas aeruginosa producing metallo β-lactamases (vim, sme, aim) in the clinical isolates of intensive care units of al-zahra hospital in isfahan, iran

background :    pseudomonas aeruginosa is a severe challenge for antimicrobial therapy, because of chromosomal mutations or exhibition of intrinsic resistance to various antimicrobial agents such as most β-lactams. we undertook this study to evaluate the existence of sme, aim and vim metallo-beta lactamases encoding genes among p. aeruginosa strains isolated from icu patients in al-zahra hospital in isfahan, iran.   methods :  in a retrospective cross sectional study that was conducted between march 2012 to april 2013, in total 48 strains of p. aeruginosa were collected from clinical specimens of bedridden patients in icu wards. susceptibility test was performed by disc diffusion method. all of the meropenem resistant strains were subjected to modified hodge test (mht) for detection of carbapenemases. multiplex pcr was performed for detection of vim , blaaim , blasme genes.   results :    in disk diffusion method imipenem and meropenem showed the most and colistin the least resistant antimicrobial agents against p. aeruginosa strains. of the 48 isolates 36, (75%) were multidrug resistant. amplification of β-lactamase genes showed the presence of blavim genes in 7 (%14.6) strains. all of the isolates were negative for blasme and blaaim genes. we couldn’t find any statistically significance difference among presence of this gene and mdr positive, age or source of the specimen.   conclusion :   as patients with infections caused by mbl-producing bacteria are at an intensified risk of treatment failure, fast determination of these organisms is necessary. our findings may provide useful insights in replace of the appropriate antibiotics and may also prevent mbls mediated resistance problem.