Alterations of Antimicrobial Resistance Genes in the Clinical Multidrug-Resistant Acinetobacter baumannii Isolates

This study purposed to investigate the antibiotic susceptibility data and the expression of resistance genes in Acinetobacter baumannii clinical isolates obtained from a military hospital in Vietnam. Antimicrobial susceptibility testing was conducted using both the disc diffusion method and the VITEK 2 automated system. The expression of ten key resistance genes associated with beta-lactamases, carbapenems, and aminoglycosides was assessed using reverse transcription polymerase chain reaction (RT-PCR) method, gene expression quantified via QuantityOne software. Among the analyzed isolates, 83.33% exhibited multidrug resistance, while only 16.67% remained susceptible to antibiotics. The isolates demonstrated the highest resistance rates to beta-lactams and fluoroquinolones, whereas colistin (91.67%) and amikacin (60%) showed the highest levels of effectiveness. RT-PCR analysis revealed ubiquitous expression of the carO gene (100%) and a high prevalence of adeB (96.67%). Additionally, bla _OXA-51-like, adeJ, bla _OXA-23-like, and oprD were detected in 93.33%, 90%, 80%, and 70% of the isolates, respectively. In contrast, aadA1, armA, and adeG were expressed in less than half of the samples. These findings indicate a widespread distribution of several antibiotic resistance genes among A. baumannii isolates, especially a significant threat posed by multidrug-resistant strains in clinical settings. The results underscore the urgent need for robust molecular surveillance and infection control strategies in hospitals to prevent the further spread of these resistant pathogens and to improve treatment outcomes.