Background: Pseudomonas aeruginosa is one of the most important agents causing nosocomial infections worldwide. Multidrug
resistance of isolated bacteria from nosocomial infections makes it difficult and sometimes impossible to treat.
Objectives: The aim of the present study was to investigate the antibiotic resistance and association between blaIMP and blaVIM genes with
resistance to meropenem and imipenem among P. aeruginosa strains isolated from Iranian patients in ICU wards of Hamadan, IR Iran.
Patients and Methods: In this cross-sectional study, 100 P. aeruginosa strains were isolated from bedridden patients in ICU wards of three
university hospitals during five months in 2012. Isolates were confirmed at species level using biochemical tests. Their susceptibility to 18
antibiotics was assessed using Kirby-Bauer disc diffusion method. The minimum inhibitory concentration (MIC) was determined by E-test
method. Single PCR was used for detecting blaVIM, and blaIMP genes.
Results: The highest resistance rates of the isolates to ampicillin/sulbactam, tigecycline, and cefotaxime were 95%, 76%, and 67%,
respectively. The lowest resistance rates were observed by colistin sulfate (96%), piperacillin/tazobactam (81%), amikacin (77%), aztreonam
(77%), meropenem (76%), imipenem (76%), cefepime (76%), piperacillin (74%), ceftazidime (74%), gentamycin (72%), tobramycin (73%), and
levofloxacin (70%) . E-test illustrated that 24% of the isolates were resistant to imipenem (MIC: 32 µg/mL). In contrary to blaVIM gene that
was not detected in any isolate, blaIMP gene was detected in 4% of the isolates. No statistically significant association was observed between
resistance rates to imipenem and meropenem with aforementioned genes.
Conclusions: Prevalence of P. aeruginosa strains drug resistance in our areas was very high and alerting, but the other antibiotics were
effective enough to be used in treatment of the infection. Overall, low resistance rate in this region was probably resulted from low
prevalence of metallo-β-lactamases producing strains. Permanent monitoring of changes in P. aeruginosa resistance would help to
determine national priorities for local intervention efforts.