Molecular Epidemiology and MLST-Based Typing of Pandrug-Resistant Acinetobacter baumannii Clinical Isolates in Iraq: A Cross-Sectional Study.

Background & objective: Acinetobacter baumannii is a globally recognized nosocomial pathogen capable of developing multidrug resistance. This study investigates antibiotic resistance patterns, evaluates common resistance genotypes, and explores the genetic relatedness of PDR A. baumannii clinical isolates from hospitals in the Middle Euphrates region of Iraq.

Methods: Fourteen PDR A. baumannii isolates were obtained and subjected to antimicrobial susceptibility testing using the Vitek-2 compact system. Resistance genes were identified via conventional PCR, and clonal relationships were analyzed using multilocus sequence typing (MLST).

Results: Among 175 A. baumannii isolates, 8% (14/175) were classified as PDR strains, exhibiting resistance to all tested antibiotics. TEM was the most prevalent resistance gene (50%), followed by CTX-M (43%). SHV, IMP, KPC, OXA-48, and Mcr-1 genes were absent in all PDR isolates. MLST analysis identified five sequence types (STs): ST2, ST218, ST138, ST123, and ST460, with ST2 being the most common (50%).

Conclusion: The high prevalence of PDR A. baumannii strains in Iraq highlights the need for enhanced antibiotic surveillance. A comprehensive molecular investigation is necessary to mitigate the spread of these resistant pathogens.