| Summary: | Solmaz Ohadian Moghadam,1 Davoud Afshar,2 Mohammad Reza Nowroozi,1 Amir Behnamfar,1 Amirreza Farzin1 1Uro-Oncology Research Center, Tehran University of Medical Sciences, Tehran, Iran; 2Department of Microbiology and Virology, Zanjan University of Medical Sciences, Zanjan, IranCorrespondence: Solmaz Ohadian MoghadamUro-Oncology Research Center, Tehran University of Medical Sciences, Tehran, IranTel/ Fax +98 21 66 43 77 25Email s-ohadian@sina.tums.ac.irPurpose: Given the importance of treatment failure due to multidrug-resistant (MDR) strains, studies on population structure of these organisms are necessary to improve control strategies. Accordingly, the current study aimed to determine the prevalence of carbapenem-resistant P. aeruginosa (CRPA) at a teaching referral hospital in Iran and to analyze their molecular clonality by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) for epidemiological purposes.Methods: In this study, modified Hodge test (MHT) and double-disk synergy test (DDST) were used for carbapenemase production and metallo-β-lactamases (MBLs) screening, respectively. All P. aeruginosa isolates were tested for antimicrobial resistance. Moreover, MBL genes (blaIMP, blaVIM, blaSPM, blaNDM) were detected by multiplex PCR assay.Results: Among 68 P. aeruginosa clinical isolates, 38 (55.88%) isolates were CRPA. Antibiotic susceptibility testing revealed that most of these isolates were MDR. PFGE analyses showed 5 common types and 27 single types among CRPA isolates. MLST analysis revealed three major clusters (MLST-sequence types (STs): 235, 357, and 861) among them. The 30 non-CRPA isolates corresponded mainly to MLST-STs 253, 360, and 446.Conclusion: Our results showed that internationally distributed MLST-STs with widely genomic diversity have spread in our hospital, and clonal expansion of MDR strains of P. aeruginosa was described as well.Keywords: carbapenem-resistant P. aeruginosa, CRPA, carbapenemase, metallo-β-lactamases, MBLs, multidrug-resistant, MDR, Pseudomonas aeruginosa, multilocus sequence typing, MLST, pulsed-field gel electrophoresis, PFGE
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