Farzin Khorvash - Department of Infectious Diseases, Nosocomial Infection Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
Mohammad reza Yazdani - Department of Infectious Diseases, Infectious Diseases and Tropical Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
Shiva Shabani - Department of Infectious Diseases, Isfahan University of Medical Sciences, Isfahan, Iran
Houri Alizadeh - Department of Microbiology, Science and Research, Islamic Azad University, Shiraz, Iran
Ali asghar Soudi - Department of Infectious Diseases, Isfahan University of Medical Sciences, Isfahan, Iran
Parisa Shoaei - Department of Microbiology, Science and Research, Islamic Azad University, Shiraz, Iran
Behrooz Ataei - Department of Infectious Diseases, Infectious Diseases and Tropical Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
Majid Yaran - Department of Infectious Diseases, Acquired Immunodeficiency Research Center, Isfahan University of Medical Sciences, Isfahan, Iran

Introduction: Pseudomonas aeruginosa is a serious challenge for antimicrobial therapy, due to chromosomal mutations or intrinsic resistance to various antimicrobial agents, such as Metallo-β-Lactams (MBL). This study aimed to investigate the prevalence of β-lactamases encoding genes among P. aeruginosa strains isolated from intensive care unit (ICU) patients by phenotypic and multiplex PCR methods. Methods: A total of ۴۸ non-duplicate strains of P. aeruginosa were collected from different clinical specimens of patients hospitalized in ICU wards of a teaching hospital in Isfahan, Iran. Susceptibility test was performed by disk diffusion method. All meropenem resistant strains were subjected to modified Hodge test (MHT) for detection of carbapenemases. Multiplex PCRs were performed to detect β-lactam-resistant P. aeruginosa isolates. Results: In disk diffusion method, P. aeruginosa strains showed the most (۹۷.۹%) resistance against imipenem and meropenem and the least (۴۵.۸%) against colistin. Thirty-six (۷۵%) out of the ۴۸ isolates were multidrug resistant. PCR amplification of β-lactamase genes showed the presence of blaVIM genes in ۷ (۱۴.۶%) and blaIMP in ۱۵ (۳۱.۳%) strains. Also, blaSME, SPM, GIM, AIM and NDM genes were not observed in any of the strains. We only found a statistically significance difference between the presence of blaIMP gene and multidrug-resistant (MDR) positivity and source of specimen (p=۰.۰۰۹ and ۰.۰۰۲, respectively). Conclusion: Rapid and reliable identification of MBLs appears to be necessary for effective treatment of related infections. Besides, our results may provide useful perception to make a more appropriate choice of antibiotics, which may put a stop to carbapenem-resistant infections.

Pseudomonas aeruginosa, PCR, Carbapenem, Beta-lactamase