The FraA adhesin and Ebp pili mediate Enterococcus faecalis adhesion under fluid flow

Enterococcus faecalis is a frequent cause of infective endocarditis and catheter-associated urinary tract infections (CAUTI). Successful colonization is challenged by blood and urine flow and relies on a strong and resilient bacterial attachment. Here, we identify molecular determinants that enable E. faecalis to maintain adhesion under flow, notably the flow-related adhesin (FraA), a previously uncharacterized adhesion factor encoded by OG1RF_11764. Transcriptomic analysis revealed increased fraA expression in surface-attached bacteria exposed to shear stress. Structural predictions identified an N-terminal region with homology to characterized Gram-positive adhesins, followed by tandem CLIPPER repeats with putative isopeptide-bond-forming residues and a C-terminal cell-wall sorting signal. Using microfluidics and single-cell tracking, we found that deletion of fraA accelerated detachment from hydrophobic abiotic surfaces under fluid flow. In line with this finding, loss of fraA reduced catheter colonization in a murine CAUTI model. Analysis of 9,192 E. faecalis genomes identified FraA in 50.8% of isolates, spanning clinical and non-clinical sources, with sequence type-associated variation in CLIPPER repeat number. Another determinant, Ebp pilus, enhances adhesion at high shear stress and contributes to a shear-enhanced adhesion pattern. Collectively, these findings identify FraA as an adhesion factor contributing to medical-device colonization and together with Ebp pili support attachment across different hydrodynamic conditions. Identifying these adhesion mechanisms could inform strategies to prevent colonization of medical devices exposed to fluid flow.