Seyed Morteza Moosavi - Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
Omid Pouresmaeil - 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 - 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 - Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
Fatemeh Akhavan - 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 - 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 - Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran

Background: 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 Pseudomonas aeruginosa, a gram-negative bacterium with both intrinsic and acquired antibiotic resistance (AR) properties. nalB mutations can be found on the mexR in the P. aeruginosa 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 nalB mutants can be useful for monitoring factors affecting AR. Methods: In this study, 70 P. aeruginosa isolates identified from burn patients and antibacterial sensitivity was evaluated using the Kirby-Bauer method. We also investigated nalB mutations in samples using molecular methods including Polymerase reaction chain (PCR) and Sequencing. Results: We identified nalB mutations in 16 isolates. We also found that the increasing effect of nalB mutants induces hyper production activity of MexAB-OprM resulting in AR. Overall, these findings compliment the findings of previous reports. Conclusions: According to the resistance patterns of the samples, both Amikacin and Ciprofloxacin showed the highest resistance (%). Further, the relationship between Ciprofloxacin resistance and nalB mutations was statistically significant (p= 0.016). The results confirm that the increasing effect of nalB mutants on hyper production activity of MexAB-OprM leads to AR.

Antibiotic Resistance, Burn Infections, Hospital-Acquired Infections, Nosocomial Infections, Pseudomonas aeruginosa.