In vivo testing of an Enterococcus faecalis efaA mutant and use of efaA homologs for species identification

Abstract

Disruption of the previously described efaA (from Enterococcus faecalis antigen A) gene was generated in E. faecalis strain OG1RF and loss of an V37-kDa immunoreactive band from the mutant was demonstrated in Western blots. In a mouse peritonitis model, mice infected with the efaA fs (fs=from Enterococcus faecalis) mutant showed more prolonged survival than mice infected with the parent strain OG1RF. These results suggest that efaA fs encodes a function important for infection of mice by enterococci. An efaA-like gene was also identified in E. faecium DNA libraries and its deduced amino acid sequence showed 73% similarity to EfaA of E. faecalis and 42^63% similarities to a group of streptococcal virulence and adhesion associated proteins that are components of ATP-binding cassette transport systems. Intragenic probes representing efaA fs , recA fs , efaA fm (fm=from E. faecium) and gyrA fm were tested for their ability to identify E. faecalis and E. faecium using colony lysates of 133 enterococci and one Streptococcus sp. Probes of E. faecium and E. faecalis origin hybridized to all isolates of E. faecium and E. faecalis, respectively, regardless of their clinical source but not to any of 29 other enterococci. These results suggest that the use of gene probes may prove helpful in identification of isolates of E. faecium and E. faecalis. z

The prolipoprotein diacylglyceryl transferase (Lgt) of Enterococcus faecalis contributes to virulence

“…According to Machata et al (2008), L. monocytogenes entry into and survival inside epithelial cells or macrophages can be affected in the absence of Lgt, and there is certainly a balance between adhesion, cytotoxicity, activation of the immune system and lipidation of lipoproteins. Of the 90 predicted lipoproteins in E. faecalis, two [EF1818 (GelE) and EF2076 (EfaA)] are involved in virulence (Qin et al, 2000;Singh et al, 1998), one (EF2488) is encoded by a gene which is a part of an operon responsible for the synthesis of a capsular carbohydrate also involved in virulence (Hancock & Gilmore, 2002), and 39 correspond to putative components of ABC transporters, among which 24 have been predicted to be important for virulence (Reffuveille et al, 2011). Indeed, metal transport is a prerequisite for growth during infection and virulence, and amino acid, peptide and amine ABC transporters, as well as pheromone-binding proteins, could have direct or indirect roles in virulence (Reffuveille et al, 2011).…”

Manganese-dependent regulation of the endocarditis-associated virulence factor EfaA of Enterococcus faecalis

“…Northern blot analysis indicated that its expression was induced by growth of the cells in medium supplemented with human serum (Lowe et al, 1995). Studies with a mouse model of peritoneal infection suggest that EfaA is a virulence factor (Singh et al, 1998). The efaA gene has since been found to be the third gene of the efaCBA operon, likely encoding an ABC-type transporter, with EfaA being the lipoprotein component.…”

Vancomycin-Resistant Enterococcus faecalis Endocarditis: Linezolid Failure and Strain Characterization of Virulence Factors

“…Colony lysates of the VR E. faecalis blood isolate from hospitalization day 5 (TX2853) were prepared by previously described methods (29) and hybridized with probes represent-ing 17 genes that encode proven or suspect virulence determinants. These included the gelatinase gene (22,26,28,30); recently described pilus-encoding genes (16); genes encoding putative MSCRAMMs (microbial surface components recognizing adhesive matrix molecules) with predicted immunoglobulin (Ig)-like folds (17,18,27; J. Sillanpää, S. R. Nallapareddy, and B. E. Murray, unpublished data); genes, including esp (33), in a predicted pathogenicity island (PAI) (15); and an acquired gene that contributes to biofilm formation (32) ( Table 1).…”