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Antimicrobial resistance, virulence factors, and genotypes of Pseudomonas aeruginosa clinical isolates from Gorgan, northern Iran


Pseudomonas aeruginosa is an important nosocomial pathogen with a capacity of resistance to multiple antibiotics and production of various extracellular and cell-associated virulence factors that clearly contribute to its pathogenicity. The objective of this study was to investigate the antibiotic susceptibility, virulence factors, and clonal relationship among clinical isolates of P. aeruginosa. Different clinical specimens from hospitalized patients were investigated for P. aeruginosa. Susceptibility of the isolates was evaluated by disc diffusion and broth microdilution methods, as described by the Clinical and Laboratory Standards Institute (CLSI) guideline. A total of 97 P. aeruginosa isolates were recovered from clinical specimens. The percentage of isolates resistant to antimicrobials was imipenem 25.77%, meropenem 15.46%, gentamicin 16.49%, tobramycin 15.46%, amikacin 16.49%, ciprofloxacin 20.61%, levofloxacin 24.74, ceftazidime 20.61%, piperacillin 15.46%, piperacillin/tazobactam 12.37%, colistin 9.27%, and polymyxin B 11.34%. Of isolates, 87.62% possessed β-hemolytic activity, 78.35% lecithinase, 59.8% elastase, 37.11% DNase, and 28.86% twitching motility. The frequency of virulence genes in isolates was lasB 82.47%, plcH 82.47%, exoA 58.76%, exoS 56.7%, and pilA 10.3%. ERIC-PCR typing clustered P. aeruginosa isolates to 19 common types (CT1-CT19) containing isolates from different hospitals and 43 single types (ST1-ST43). Colistin and polymyxin B were the most effective agents against the majority of P. aeruginosa isolates, emphasizing the effort to maintain their antibacterial activity as last-line therapy. The frequency of some virulence factors and genes was noticeably high, which is alarming. In addition, more effective strategies and surveillance are necessary to confine and prevent the inter-hospital and/or intra-hospital dissemination of P. aeruginosa between therapeutic centers.

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The authors would like to thank the staff of the selected hospitals as well as all the colleagues at the Department of Microbiology, Golestan University of Medical Sciences, Gorgan, Iran, for their laboratory cooperation.


This work was financially supported by grant 110212 from the Golestan University of Medical Sciences, Gorgan, Iran.

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Authors and Affiliations



AA, AJ, and FNS conceptualized and designed study. FNS, AA, HB, and AH performed the experiments. FNS, AA, AJ, and MASBG interpreted results and analyzed data. FNS and AI wrote the original draft. AA reviewed the manuscript and critically revised it.

Corresponding author

Correspondence to Abdollah Ardebili.

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This study was approved by the Ethics Committee of Golestan University of Medical Sciences with ethical code number IR.GUMS. REC.1398.079. All patients were verbally informed about this study, and consensus was obtained from their close relatives. In order to maintain patient’s confidentiality, participants were anonymous, and no personal information was collected or included in the study.

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The authors declare no competing interests.

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Shahri, F.N., Izanloo, A., Goharrizi, M.A.S.B. et al. Antimicrobial resistance, virulence factors, and genotypes of Pseudomonas aeruginosa clinical isolates from Gorgan, northern Iran. Int Microbiol (2022).

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  • Antibiotic resistance
  • PCR amplification
  • Pseudomonas aeruginosa
  • Virulence factors