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High Prevalence of vanA ‐Positive Vancomycin‐Resistant Enterococcus faecalis and Enterococcus faecium : Antibiotic Resistance, Biofilm Formation, and Virulence Profiles

Year: 2026

Type: article

Abstract: ABSTRACT Background Data on antimicrobial resistance (AMR), biofilm formation, and virulence traits in clinical Enterococcus isolates from central Iran remain limited. This study evaluated AMR profiles, biofilm‐forming capacity, and the prevalence of virulence and resistance genes in clinical Enterococcus isolates from Arak, Iran. Materials and Methods Fifty Enterococcus isolates obtained from 250 clinical specimens were analyzed. Antimicrobial susceptibility was determined by disk diffusion and E ‐test. Biofilm formation was quantified via the crystal violet microtiter plate assay. PCR was performed to detect virulence genes ( acm , ace , gelE , efaA , esp ) and vancomycin resistance determinants ( vanA , vanB ). Results PCR confirmation identified Enterococcus faecalis (66%, n = 33) and Enterococcus faecium (34%, n = 17). Overall, 70% of the isolates were vancomycin‐resistant enterococci (VRE) and carried the vanA gene. Notably, all E. faecium isolates demonstrated 100% resistance to vancomycin, ciprofloxacin, and levofloxacin. Regarding biofilm production, 82% of E. faecium isolates were moderate producers, with no strong producers observed, whereas 64% of E. faecalis isolates were strong biofilm formers. The efaA , gelE , and ace genes were significantly more prevalent in E. faecalis , whereas acm was predominantly detected in E. faecium . Furthermore, the presence of gelE and efaA was significantly associated with strong biofilm formation ( p < 0.05). Conclusions While E. faecalis was the predominant species, E. faecium exhibited a significantly higher burden of AMR. The alarmingly high prevalence of vanA ‐mediated vancomycin resistance, coupled with species‐specific virulence traits and robust biofilm capabilities, underscores the urgent need for stringent infection control measures and continuous molecular surveillance in healthcare settings.

Source: Health Science Reports

DOI: 10.1002/hsr2.73468