Molecular Epidemiology and Risk Factors for Carbapenem-Resistant Acinetobacter baumannii Infections in an Intensive Care Unit

Carbapenem-resistant Acinetobacter baumannii (CRAB) poses a significant threat to global health, particularly in intensive care units (ICUs). This study investigated the molecular epidemiology and risk factors associated with CRAB infections in four Iraqi ICUs. A total of 164 patients with invasive MDR A. baumannii infections were included. Demographic and clinical data were collected prospectively, and antimicrobial susceptibility testing was performed on 172 isolates (164 clinical and 8 environmental). Multiplex PCR was used to identify four key carbapenem resistance genes. The study revealed a high mortality rate (56.4%) among infected patients. The majority were male (51.6%), admitted to surgical ICUs (44.2%), and had undergone invasive procedures, including urinary catheterization (97.4%) and mechanical ventilation (67.3%). Univariate analysis identified older age (>65 years), diabetes mellitus, chronic liver failure, and prior chemotherapy treatment as independent risk factors for mortality. Antimicrobial susceptibility testing revealed alarmingly high resistance rates (>90%) to most tested antibiotics, including amikacin, ampicillin-sulbactam, ceftazidime, ciprofloxacin, and imipenem. Colistin exhibited the lowest resistance (2.2%). blaOXA-23 was the most prevalent resistance gene detected across all centers, with significantly higher frequencies in two centers. These findings emphasize the critical need for effective infection control measures, judicious antibiotic stewardship, and continuous surveillance of resistance patterns to combat the spread of MDR A. baumannii in healthcare settings. Furthermore, the development of novel therapeutic strategies is crucial to address the limited treatment options for this increasingly resistant pathogen.