Prevalence and Resistance Profiles of Acinetobacter Baumannii in the Intensive Care Unit: A Retrospective Analysis Between 2023 and 2025

Abstract

Introduction: This study investigated the prevalence and antimicrobial resistance profiles of Acinetobacter baumannii strains isolated from a tertiary intensive care unit between 2023 and 2025. Materials and Methods: Between January 2023 and August 2025, A. baumannii strains isolated from various clinical specimens in a tertiary intensive care unit were retrospectively analyzed. Identification and antibiotic susceptibility testing of the isolates were performed using the BD Phoenix 100 M50 (Becton Dickinson Company, USA) automated system, and the results were interpreted according to the standards of the European Committee on Antimicrobial Susceptibility Testing. Only one isolate per patient was included in the study. Results: A total of 566 A. baumannii isolates were evaluated. The annual isolation rates were 13.7% in 2023, 12.5% in 2024, and 17.5% in 2025, with an overall three-year average of 14.7%. Of these isolates, 77.4% were obtained from tracheal aspirates and 16.6% from blood cultures. The lowest resistance rates were observed for colistin (10.2%) and tigecycline (11.4%), while resistance rates exceeded 90% for carbapenems, aminoglycosides, and fluoroquinolones. Trend analysis revealed a significant decrease in tigecycline resistance (p< 0.001), whereas significant increasing trends were observed for cefoperazone-sulbactam, gentamicin, fluoroquinolones, cephalosporins, and carbapenems. Conclusion: A. baumannii remains a clinically significant pathogen in intensive care units and exhibits high resistance rates, particularly against broad-spectrum antibiotics. In our study, colistin and tigecycline were observed to retain relative activity. Regular surveillance of resistance patterns and the revision of empirical treatment protocols in light of these data may contribute to reducing mortality and morbidity rates.