Distribution of Virulence and Pheromone-Associated Genes Among Colonizing Enterococcus faecalis Isolates Recovered...

Background: Enterococcus faecalis is a common gastrointestinal commensal and an important opportunistic pathogen. While vancomycin resistance is well characterized, data on virulence-associated genes in colonizing isolates remain limited. Methods: A total of 44 colonizing E. faecalis isolates recovered from routine VRE screening (rectal swabs) were included in the study. The presence of the virulence-associated genes asa, esp, eep, ccf, and cpd was investigated by PCR. Antimicrobial susceptibility testing was performed using standardized methods, and isolates were subsequently classified as either vancomycin-resistant (VRE) or vancomycin-susceptible (VSE). A cumulative virulence gene score was calculated for each isolate and compared between the two groups. Results: Virulence-associated genes were heterogeneously distributed. Overall, the prevalence of the investigated virulence genes was cpd (33/44), eep (26/44), esp (24/44), ccf (22/44), and asa (8/44). Among these, only esp was significantly more prevalent in VRE than in VSE isolates (p < 0.01). VRE isolates showed a significantly higher median virulence gene score compared to VSE isolates (3 [IQR: 2-4] vs. 2 [IQR: 2-3]; p = 0.028, Mann-Whitney U test). The esp gene was more frequently detected among VRE isolates, while pheromone-associated genes displayed no clear group-specific pattern. Conclusions: Colonizing E. faecalis isolates carried a heterogeneous repertoire of the selected virulence-associated genes, with a higher burden of these genes among VRE isolates. These findings contribute additional data from Eastern Europe on the molecular characteristics of colonizing E. faecalis populations and support further investigation of their epidemiological relevance in healthcare settings.