Table 3.
Virulence factors of enterococci classified by function.
| Virulence Factors | Classification | Type of Research | Enterococcus strains | Functions | Reference |
|---|---|---|---|---|---|
| Adhesin to collagen of E. faecalis (Ace) | Adherence | Cell culture and analysis of clinical isolates from patients with endocarditis | E. faecium OG1RF | Ability to bind with collagen type I and IV, as well as laminin | Nallapareddy et al., 2000 [47] |
| Cell wall-anchored collagen membrane adhesin (Acm) | Adherence | Cell culture and analysis of isolates from patients with severe clinical infections |
E. faecium TX0054 E. faecium TX2535 E. faecium TX2555 |
Ability to bind with collagen type I | Nallapareddy et al., 2003 [48] |
| Endocarditis- and biofilm-associated pili (Ebp) | Adherence | Analysis of isolates from rats | E. faecalis OG1RF | Contribution to biofilm formation and adherence to fibrinogen | Nallapareddy et al., 2006 [49] |
| Enterococcus collagen-binding adhesin (EcbA) |
Adherence | Cell culture and analysis of hospital-acquired isolates in vitro | E. faecalis E1162 | Ability to bind with collagen type I, IV, V, and fibrinogen | Hendrickx et al., 2009 [50] |
| E. faecalis antigen A (EfaA) | Adherence | In vitro analysis of clinical isolates from patients with endocarditis | E. faecalis EBH1 | Potential function as an adhesin in the endocardium | Lowe et al., 1995 [51] |
| Extracellular surface protein (Esp) | Adherence | In vivo experiment regarding urinary tract infection with a mouse model | E. faecalis MMH94 | Colonization and survival in the bladder | Shankar et al., 2001 [52] |
| Promotion aggregation complex (PrgB) |
Adherence | In vitro experiment with PrgB (AS 10) wildtype and PrgB mutant | E. faecalis OG1RF | Promotion of aggregation and biofilm formation | Schmitt et al., 2018 [53] |
| Second collagen adhesin of E. faecium (Scm) | Adherence | Cell culture and analysis of endocarditis isolates |
E. faecium TX0068 E. faecium TX0074 |
Ability to bind with specificity to collagen type V | Sillanpää et al., 2008 [54] |
| Serine glutamate repeat A (SgrA) | Adherence | Cell culture and analysis of hospital-acquired isolates in vitro |
E. faecium U0317 E. faecium E1162 |
Potential contribution to biofilm formation by binding nidogen and fibrinogen | Hendrickx et al., 2009 [50] |
| Gelatinase (GelE) | Exoenzyme | Cell culture and analysis in vitro | E. faecalis (non-specified) | Cleavage of complement C3, resulting in activation of the complement system | Park et al., 2008 [55] |
| Serine Protease (SprE) | Exoenzyme | In vivo experiment with rabbit model of endophthalmitis | E. faecalis OG1RF | Activation of fsrABC by working together with GelE (Attenuation of endophthalmitis pathogenesis in rabbits with SprE-deficient mutant) |
Engelbert et al., 2004 [56] |
| Cytolysin (Cyl) | Exotoxin | Translocation experiment in vitro | E. faecalis JH22, E. faecalis TX1322 | Cleavage of complements C3 and iC3b | Zeng et al., 2005 [57] |
| In vitro analysis of clinical isolates in patients | E. faecalis (non-specified) | Higher occurrence of Cyl among clinical pathogens | Huycke et al., 1995 [58] |
||
| Biofilm on plastic D (BopD) | Biofilm | In vivo experiment with mice |
E. faecalis T9, E. faecalis 10D5, E. faecalis TDM |
Contribution to biofilm formation | Creti et al., 2006 [59] |
| Quorum-sensing complex (FsrABC) |
Biofilm | Comparative Transcriptional Analysis |
E. faecalis OG1RF, E. faecalis TX5266 |
Encoding of a two-component signal transduction system for initiation of quorum sensing | Bourgogne et al., 2006 [60] |
| Capsular polysaccharides (Cps) | Immune Modulation | Cell culture and analysis in vitro |
E. faecalis V583, E. faecalis LT02, E. faecalis LT06 |
Higher resistance to opsonophagocytosis | Thurlow et al., 2009 [61] |
None of the above virulence factors have been reported in enterococci used in probiotics.