Association of virulence genes with biofilm formation in clinical Enterococcus faecalis isolates: a systematic review and meta-analysis

Abstract

This systematic review and meta-analysis examined association between virulence gene carriage and phenotypic biofilm formation in human clinical Enterococcus faecalis isolates. PubMed, Scopus, and Web of Science databases were searched on April 9, 2026, and the protocol was registered in PROSPERO (CRD420261405485). Eligible studies used microplate-based biofilm assessment, detected virulence genes, and provided extractable 2 × 2 data. Random-effects meta-analyses were performed using odds ratios (OR). Twenty-six studies comprising 1848 isolates were included. For strong versus non-strong biofilm formation, esp (OR 2.34, 95% CI 1.32–4.13), efaA (OR 26.28, 95% CI 1.12–614.84), and sprE (OR 3.06, 95% CI 1.18–7.92) showed significant associations, although efaA and sprE estimates were based on few studies and were imprecise. For any biofilm versus no biofilm formation, asa1 (OR 2.55, 95% CI 1.39–4.67), esp (OR 2.71, 95% CI 1.82–4.04), agg (OR 1.87, 95% CI 1.25–2.78), and cylA (OR 2.17, 95% CI 1.20–3.91) were significant. Sensitivity analyses identified esp as the most consistent association, although heterogeneity remained for strong biofilm formation. Gene-biofilm associations were gene-specific and phenotype-dependent. esp positivity alone is insufficient to predict biofilm phenotype because biofilm formation is multifactorial and context dependent.