en میکروب شناسی Microbiology مقالات اصلی Original Article <div style="text-align: justify;"><strong><em>Background:</em></strong> Due to extensive damage to the skin, burn victims may acquire life-threatening infections. Though the skin primarily protects against microbial invasions, a large number of bacteria, fungi, and viruses can be isolated from burn patients, specifically <em>Pseudomonas aeruginosa</em>, a gram-negative bacterium with both intrinsic and acquired antibiotic resistance (AR) properties. <em>nalB </em>mutations can be found on the <em>mexR</em> in the <em>P. aeruginosa</em> chromosome. This mutation can induce overexpression of the mexAB-oprMoperon, and affect the MexAB-OprM efflux pump, which removes antimicrobial agents from the bacterial cell. Identifying <em>nalB </em>mutants can be useful for monitoring factors affecting AR.<br> <br> <strong><em>Methods:</em></strong> In this study, 70 <em>P. aeruginosa </em>isolates identified from burn patients and antibacterial sensitivity was evaluated using the Kirby-Bauer method. We also investigated <em>nalB</em> mutations in samples using molecular methods including Polymerase reaction chain (PCR) and Sequencing.<br> <br> <strong><em>Results</em></strong><strong><em>:</em></strong> We identified <em>nalB</em> mutations in 16 isolates. We also found that the increasing effect of <em>nalB</em> mutants induces hyper production activity of MexAB-OprM resulting in AR. Overall, these findings compliment the findings of previous reports.<br> <br> <strong><em>Conclusions:</em></strong> According to the resistance patterns of the samples, both Amikacin and Ciprofloxacin showed the highest resistance (%). Further, the relationship between Ciprofloxacin resistance and <em>nalB</em> mutations was statistically significant (<em>p</em>= 0.016). The results confirm that the increasing effect of <em>nalB</em> mutants on hyper production activity of MexAB-OprM leads to AR.</div> Antibiotic Resistance, Burn Infections, Hospital-Acquired Infections, Nosocomial Infections, Pseudomonas aeruginosa. 140 146 http://rbmb.net/browse.php?a_code=A-10-441-1&slc_lang=en&sid=1 Seyed Morteza Moosavi 100319475328460017563 100319475328460017563 No Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Omid Pouresmaeil 100319475328460017564 100319475328460017564 No Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran & Department of Medical Laboratory Sciences, Varastegan Institute for Medical Sciences, Mashhad, Iran. Hengameh Zandi 100319475328460017565 100319475328460017565 No Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran & Department of Parasitology and Mycology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Sahar Emadi 100319475328460017566 100319475328460017566 No Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Fatemeh Akhavan 100319475328460017567 100319475328460017567 No Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran & Department of Medical Microbiology, School of Medicine, Iran University of Medical Science, Tehran, Iran Alireza Torki 100319475328460017568 100319475328460017568 No Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran & Department of Medical Microbiology, School of Medicine, Iran University of Medical Science, Tehran, Iran Akram Astani astani_ir@ssu.ac.ir 100319475328460017569 100319475328460017569 Yes Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran