Antimicrobial Resistance and Molecular Epidemiology of Enterococcus Species Isolated at the University Hospitals of Sfax, Tunisia.

Abstract

Enterococci are major causes of both community-acquired and healthcare-associated infections. The rapid global dissemination of multidrug-resistant clones poses a major challenge to clinical management and infection control. The aim for the present study was to investigate the prevalence, antimicrobial resistance patterns, virulence genes, and molecular epidemiology of Enterococcus species isolated from clinical specimens in university hospitals of Sfax, Tunisia. A descriptive, hospital-based, cross-sectional surveillance study was conducted between March 2020 and February 2021. It included all Enterococcus strains isolated in the Microbiology Department of Habib Bourguiba University Hospital. Enterococcus isolates were tested for antimicrobial susceptibility in accordance with European Committee on Antimicrobial Susceptibility Testing guidelines. Polymerase chain reaction assays were performed to detect resistance genes (vanA, vanB, ermA, ermB, ermC, msrA, mefE, vga, vat, vgb), virulence genes (gelatinase [gelE], aggregation substance, enterococcal surface protein [esp], cytolysin, hyaluronidase), and the IS16 marker associated with the clonal complex 17 (CC17) lineage. A total of 231 Enterococcus isolates were recovered, including Enterococcus faecalis (62.3%) and Enterococcus faecium (34.2%). All E. faecalis isolates were susceptible to ampicillin, vancomycin, and linezolid; all E. faecium isolates were resistant to ampicillin, and 7.6% exhibited vanA-mediated glycopeptide resistance. The ermB gene was the predominant macrolide resistance determinant. Among E. faecium, esp (74.7%) was the most prevalent virulence gene, whereas E. faecalis mainly harbored gelE (78.5%). The IS16 element, characteristic of CC17 clones, was detected in 86.1% of E. faecium isolates. The present study highlights the emergence of multidrug-resistant E. faecium strains with molecular features suggestive of CC17 affiliation in hospital settings in Sfax, Tunisia, underscoring the urgent need for stronger infection control and antimicrobial stewardship programs.