Prevalence and associations of antibiotic resistance and biofilm formation with molecular determinants in clinical Acinetobacter baumannii isolates

Abstract

Acinetobacter baumannii is a notorious opportunistic pathogen commonly associated with healthcare-associated infections and multidrug resistance. Its survival in hospital environments, biofilm formation, and iron acquisition systems complicate treatment. Understanding virulence factors and resistance mechanisms is crucial for developing effective control strategies. This study investigates genetic determinants of virulence and antibiotic resistance in selected MDR/XDR clinical A. baumannii isolates and explores their relationship with phenotypic traits. The selected MDR/XDR clinical A. baumannii isolates were identified using standard microbiological methods. Antimicrobial susceptibility followed CLSI guidelines. Biofilm formation was assessed using the tissue culture plate method. Molecular confirmation and detection of the selected genes were performed by multiplex PCR. In this study, 150 non-duplicate MDR/XDR clinical A. baumannii isolates were selectively collected from routine laboratory records based on their resistance profiles. Among the selected isolates, (84%) were XDR and (16%) were MDR. blaOXA-51 and adeA gene were present in all selected MDR/XDR isolates (100%). Among MBL genes, blaIMP, blaNDM, and blaVIM were detected in 82%, 64%, and 52% of the selected studied isolates, respectively, with each isolate carrying at least one or more of these genes, while blaKPC was absent. Biofilm formation was observed in 96% of the selected MDR/XDR studied isolates, including 36% strong, 44% moderate, and 16% weak producers. Virulence genes basD, surA1, and bfmR were present in all selected MDR/XDR isolates, while csuE, ompA, and bap were detected in 94%, 80%, and 46%, respectively. The high detection rates of metallo-β-lactamases, biofilm formation, and iron acquisition genes among the selected MDR/XDR clinical isolates, highlight the importance of continuous surveillance and infection control measures. Notably, a significant association was observed between biofilm formation and antimicrobial susceptibility profile for most tested antibiotics. Additionally, the antimicrobial susceptibility profile of the selected MDR/XDR A. baumannii showed statistically significant and non-significant associations with both antibiotic resistance genes and biofilm genes.