Multidrug resistance patterns among clinical isolates of Acinetobacter baumannii from Imam Khomeini Hospital, Tehran

Background and Objectives Acinetobacter baumannii has emerged as one of the most significant opportunistic pathogens in hospital environments due to its remarkable ability to acquire and disseminate antibiotic resistance genes. It is a major cause of healthcare-associated infections, particularly in intensive care units (ICUs), leading to ventilator-associated pneumonia, wound infections, and septicemia. The present study aimed to investigate the antibiotic resistance patterns of clinical A. baumannii isolates and to assess the prevalence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) phenotypes among them. Materials and Methods In this descriptive-analytical study, several clinical isolates of A. baumannii, categorized into ABI and ABH groups, were collected from hospitalized patients in a tertiary-care hospital. Bacterial identification was performed using standard biochemical and molecular methods. Antimicrobial susceptibility testing was conducted by the disk diffusion (Kirby–Bauer) method in accordance with CLSI guidelines. Results Antibiogram results showed that more than 50% of the isolates were resistant to imipenem and meropenem, while high levels of resistance were also observed to cephalosporins and fluoroquinolones. Colistin remained the most effective antibiotic, with only a small percentage of isolates showing resistance. Comparative analysis showed that isolates from the (ABI) group showed a broader resistance profile than isolates from the (ABH) group. Overall, 92% of the isolates were classified as multidrug-resistant (MDR) and 47% as extensively resistant (XDR). Discussion Implementation of rigorous antibiotic stewardship programs and continuous resistance surveillance are urgently needed to prevent the dissemination of MDR and XDR A. baumannii strains in clinical settings. Conclusion The findings of this study demonstrate an alarming prevalence of antibiotic resistance among A. baumannii isolates in the hospital environment, posing a serious threat to infection control and patient safety.