Abstract

Acinetobacter baumannii has crystallized into a formidable adversary within clinical environments, primarily attributable to its adeptness at biofilm formation and its notable resistance to a spectrum of antibiotics. This study included 10 clinical isolates of A. baumannii, assessing their biofilm production capabilities, antibiotics resistance profiles, and expression levels of efflux pump genes (adeA besides adeS). Notably, only 10 isolates (33.3%) demonstrated quantifiable biofilm production, bifurcated into 5 categorized as moderate biofilm producers (optical density range: 0.638–0.845) and 5 as strong producers (optical density range: 0.980–1.67). Antibiotic susceptibility evaluations conducted via the VITEK 2 system illuminated that 80% of the isolates exhibited resistance to imipenem, while 60% displayed resistance to amikacin, contrastingly, merely 13.3% manifested resistance to colistin. Gene expression analysis unveiled a broad spectrum of fold changes in adeA expression (0.0089 to 9.11) and adeS (0.0161 to 28.73). Multidrug-resistant (MDR) isolates were characterized by a markedly higher median fold expression for adeS (13.4) in comparison to non-MDR counterparts (1.46), nevertheless this disparity did not influence statistical significance (p > 0.05). Likewise, a comparative analysis of biofilm phenotypes indicated that moderate biofilm producers exhibited marginally elevated median expression levels of adeA (3.7) relative to strong producers (1.4), yet once again, this difference lacked statistical significance. A resistance heatmap elucidated pronounced clustering of high resistance among MDR isolates, particularly regarding beta-lactams and aminoglycosides. These findings imply that while expression levels of adeA and adeS are indeed variable and sometimes heightened in MDR or biofilm-forming isolates, a consistent correlation remains elusive. This highpoints intricate in addition to multifaceted nature of antimicrobial resistance and biofilm regulation in A. baumannii, advocating for expansive molecular profiling to unearth more dependable resistance markers.