High Prevalence of vanA‐Positive Vancomycin‐Resistant Enterococcus faecalis and Enterococcus faecium: Antibiotic Resistance, Biofilm Formation, and Virulence Profiles
- 1Infectious Diseases Research Center (IDRC) Arak University of Medical Sciences Arak Iran
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.
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BibTeX
@article{mezher2026high,
title = {{High Prevalence of vanA‐Positive Vancomycin‐Resistant Enterococcus faecalis and Enterococcus faecium: Antibiotic Resistance, Biofilm Formation, and Virulence Profiles}},
author = {Rusul Tareq Mezher and Rasha Radhi Abbas and Hayder Akram Jabbar and Majid Akbari and Milad Kashi and Zahra Chegini and Aref Shariati},
journal = {Health Science Reports},
year = {2026},
month = nov,
doi = {10.1002/hsr2.73468},
url = {https://doi.org/10.1002/hsr2.73468},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - High Prevalence of vanA‐Positive Vancomycin‐Resistant Enterococcus faecalis and Enterococcus faecium: Antibiotic Resistance, Biofilm Formation, and Virulence Profiles
AU - Rusul Tareq Mezher
AU - Rasha Radhi Abbas
AU - Hayder Akram Jabbar
AU - Majid Akbari
AU - Milad Kashi
AU - Zahra Chegini
AU - Aref Shariati
PY - 2026
DA - 2026/11/04
JO - Health Science Reports
DO - 10.1002/hsr2.73468
UR - https://doi.org/10.1002/hsr2.73468
AB - 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.
SN - 2398-8835
ER -