Genetic characterization of Pseudomonas aeruginosa-resistant isolates at the university teaching hospital in 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 bla(OXAgroup-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.