Genetic characterization of Pseudomonas aeruginosa-resistant isolates at the university teaching hospital in Iran


1 Department of Microbiology, School of Medicine, Isfahan University of Medical sciences, Isfahan, Iran

2 Department of Microbiology, School of Medicine, Zahedan University of Medical Sciences, Zahedan; Department of Microbiology, School of Medicine, Isfahan University of Medical sciences, Isfahan, Iran

3 Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran


Background: Pseudomonas aeruginosa is an opportunistic pathogen that is commonly responsible for nosocomial infections. The aim of this study was to perform a genotyping analysis of the Pseudomonas aeruginosa-resistant isolates by the multilocus sequence typing (MLST) method at the university teaching hospital in Iran.
Materials and Methods: Antimicrobial susceptibility was analyzed for P. aeruginosa isolates. Ceftazidime-resistant (CAZ res ) isolates with a positive double-disc synergy test were screened for the presence of extended-spectrum β-lactamase-encoding genes. Phenotypic tests to detect the metallo-β-lactamase strains of P. aeruginosa were performed on imipenem-resistant (IMP res ) isolates. Selected strains were characterized by MLST.
Results: Of 35 P. aeruginosa isolates, 71%, 45% and 45% of isolates were CAZ res , IMP res and multidrug resistant (MDR), respectively. Fifty-seven percent of the isolates carried the blaOXAgroup-1 . All the five typed isolates were ST235. Isolates of ST235 that were MDR showed a unique resistance pattern.
Conclusion: This study shows a high rate of MDR P. aeruginosa isolates at the university teaching hospital in Iran. It seems MDR isolates of P. aeruginosa ST235 with unique resistance pattern disseminated in this hospital.


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