Elham Jafarzadeh
Masoud Kargar
Susan Amiri

Background: This research aimed to examine the frequency of resistance to antimicrobial agents and their variations in Pseudomonas aeruginosa clinical isolates, which are accountable for invasive infections in the southern part of Iran, from ۲۰۱۸ to ۲۰۲۲. Methods: A retrospective study was conducted, involving the gathering of microbiological data from Taleghani Burn Hospital from ۲۰۱۸ to ۲۰۲۲. The primary variables under scrutiny were department, sample origin, the antiprogram system (e.g., disc diffusion and strip methods, and clinical laboratory standards), and the rate or percentage of resistant isolates investigated by antimicrobial susceptibility testing. The interpretation criteria employed for the study were those of the Clinical Laboratory Standards Institute (CLSI). And the percentage of resistant isolates was also taken into consideration. Results: The disc diffusion and strip method is the most commonly used approach for antimicrobial susceptibility testing. According to the CLSI, resistance rates ranged from ۳.۶۴% (colistin) to ۷۷.۳۸% (amikacin). The rates of antimicrobial resistance remained relatively constant over time in ۲۰۱۸-۲۰۲۲. Approximately ۶۷.۶۲% of isolates were multidrug resistant, and the remaining ۹.۴۶% were extensively drug-resistant. Wound and urine isolates demonstrated higher resistance, except for amikacin and piperacillin, than those from blood culture and biopsy. Conclusion: Antimicrobial resistance is widely prevalent in P. aeruginosa, a common bacterium in southern Iran. The findings revealed the highest resistance rates for commonly used antibiotics such as amikacin, piperacillin, ceftazidime, and meropenem. However, colistin and nitrofurantoin are more effective against this bacterium. The wound and urine isolates represented the highest resistance rates, indicating the need for prompt and appropriate treatment. Interestingly, the resistance rates for most antibiotics remained relatively stable during the study period, emphasizing the need to develop alternative treatments for P. aeruginosa infections.