National Research Institute of Tuberculosis and Lung Disease (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran TANAFFOS (Respiration) 1735-0344 24 2 2025 04 01 Evaluation of Biofilm Formation, Alginate Production, Pattern of Drug Resistance, and the Presence of Efflux Pump MexAB-OprM, MexXY (-OprA), and AmpC Gene in Clinical Isolates of Pseudomonas aeruginosa 163 173 734848 EN Saeid Besharati Department of Microbiology and Microbial Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran Mohammad Rahbar Departments of Microbiology, Iranian Reference Health Laboratory Research Center, Ministry of Health and Medical Education, Tehran, Iran Neda Soleimani Department of Microbiology and Microbial Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran Journal Article 2024 11 16 Background: One of the most significant factors contributing to multidrug resistance in Pseudomonas aeruginosa infections is the formation of biofilms and the production of alginate. This study aimed to evaluate the overexpression of efflux pumps MexAB-OprM, MexXY (-OprA), and the AmpC gene and investigate biofilm and alginate in P. aeruginosa clinical isolates. Materials and Methods: One-hundred isolates of P. aeruginosa were collected two government-specialized hospitals from February 2024 to June 2024 in Tehran, Iran. The disk diffusion method was used for antimicrobial susceptibility and detecting the pattern of antibiotics. We used a microtiter plate and carbazole assay to investigate biofilm formation and alginate production, respectively. We investigated the efflux pump MexAB-OprM, MexXY (-OprA), and the AmpC gene expression with real-time PCR and its correlation with biofilm, alginate, and antibiotic resistance. Results: 30 multidrug-resistant (MDR) isolates were detected, and 27 antibiotic patterns were obtained. A significant relationship between biofilm formation and resistance to PRL was observed (P<0.01). All of the samples with more than 250µg/ml level of alginate production were resistant to Piperacillin-Tazobactam (PTZ), which was significant (P<0.05). Also, the relationship between alginate production and strong biofilm formation was significant. The expression of resistance-nodulation-division (RND) efflux pumps MexAB-OprM, MexXY (-OprA), and AmpC gene in MDR isolates of P. aeruginosa was significantly increased. Conclusion: High prevalence of MDR, along with high expression of efflux pump genes, was concerning. High production of biofilm formation and its relationship with alginate were observed in P. aeruginosa clinical isolates. To prevent the spread of antibiotic resistance, implementing monitoring methods and not overusing and abusing antibiotics is necessary.

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