7%, sensitivity to complement-mediated phagocytosis did not differ between the 12030 wild type and 12030ΔbgsB (Additional file 2). Furthermore, rabbit antibodies raised against whole bacterial cells of E. faecalis 12030 mediated opsonophagocytic killing of 12030ΔbgsB comparable U0126 to levels obtained for the wild-type strain (Additional file 2). The loss of glycolipids from the cell membrane is associated with reduced adherence to Caco-2 cells and impaired biofilm formation We recently showed that deletion of bgsA leads to loss of biofilm formation on polystyrene and to reduced adherence to Caco-2 cells [5]. Partial deletion of bgsB also strongly impaired biofilm formation, reducing production

by 50% (Figure 3). This defect in biofilm formation was not a result of decreased initial attachment (i.e., bacteria attached in ≤ 30 min of incubation); rather, it was due to defective accumulation of biofilm mass after initial attachment (Figure 3). Over a period of 24 h, biofilm mass of wild-type bacteria on polystyrene grew in a linear fashion. In contrast, the amount of biofilm produced by bgsB and bgsA mutants selleckchem remained constant at the level of initial attachment. Adhesion to colonic epithelial cells (Caco-2 cells) was also impaired in 12030ΔbgsB, reaching only 50% of the adhesion of wild-type bacteria (Figure 3).

bgsB contributes to virulence during bacteremia in mice Previous experiments with a bgsA deletion mutant in E. faecalis showed that it leads

to an attenuation of virulence in a mouse bacteremia model [5]. To assess whether cell membrane glycolipids or glycolipid anchoring of LTA is required for the pathogenesis of enterococcal infections, we employed the same model to investigate the bgsB mutant. As mentioned above, 12030 wild-type and respective mutants had comparable growth characteristics. For virulence studies, we infected BALB/c mice 6 – 8 weeks old by i.v. injection, sacrificed the animals after 3 days, and enumerated the viable bacteria. Pilot experiments indicated that, with a high inoculum of 2 × 109 bacteria, infected mice are bacteremic up to 4 days without succumbing to the infection. Compared to the wild type, mice infected with 12030ΔbgsB or 12030ΔbgsA cleared significantly Ponatinib in vitro more bacteria from the bloodstream (Figure 6). No difference in virulence between 12030ΔbgsB and 12030ΔbgsA was detected in this model. Figure 6 Virulence of E. faecalis Δ bgsB in a mouse bacteremia model. Female BALB/c mice 6-8 weeks old were infected via the tail vein with stationary-phase E. faecalis strains (2.0 × 109 cfu). After 72 h mice were sacrificed and bacterial counts in the blood were enumerated. Data represent the individual bacterial counts and the geometric mean. ** P < 0.01, *** P < 0.001, Dunn’s multiple comparison test. The lower limit of detection of the assay was 10 CFU/ml blood.