Figure 1. Role for pili in the establishment of E. faecalis infection.

Enterococci may use pili (surface fibrils) for microbial attachment to host tissues (i). Surface proteins (e.g., AS, Esp, and Ace) are involved in establishing tight bacterial adherence to host cells (ii). Enterococcal aggregation induces biofilm formation (iii) and elaboration of exopolysaccharide matrix (blue surface layer). Quorum-sensing–controlled expression of protease and cytolysin mediate host cell death and spread of infection (iv). Schematic modified with permission from ASM Press (1).