blaVIM and blaIMP Genes Detection in Isolates of Carbapenem Resistant P. aeruginosa of Hospitalized Patients in Two Hospitals in Iran

Background & objective: Beta-lactam antibiotics resistance specifically Imipenem and Meropenem, the last choices of treatment, causes fatal events in patients with P.aeruginosa infection. The aim of this study was to detect the VIM and IMP of metallo-beta-lactamase genes in 103 isolates of P. aeruginosa in two Iranian hospitals. Methods: In this study, we evaluated the susceptibility of P. aeruginosa to a range of β-lactam antibiotics using disk diffusion method as a standard biochemical test. Combined disk test of Imipenem (IMP) and Imipenem plus Ethylenediaminetetraacetic acid (EDTA) was performed as a phenotypic method to find metallo-beta-lactamase producing isolates.Using conventional PCR method; we evaluated VIM and IMP of metallo-beta-lactamase (MBL) genes in 103 isolates of P.aeruginosa. Results: Twenty six (25.2%) out of 103 isolates were resistant to Imipenem and 26 (25.2%) to Meropenem. Among 26 Imipenem and Meropenem-resistant strains (25.2%), 19 cases (73.0%) were MBL producing. Using PCR method, we detected the blaVIM and blaIMP genes in 6 (5.8%) and 2(1.9%) of 19 MBL producing isolates, respectively.  Conclusions: Evaluation  of  these  carbepenemases genes improve epidemiologic researches and also, can  be  used  as  a  diagnostic  tool  for discriminating  between  antibiotics  resistant  and  sensitive  strains  of P.aeruginosa as well as follow-up the patients after treatment.