Volume 75, no. 11, p. 5399-5404, 2007. Page 5401: Figure 1 should appear as shown below.
Recently, Guiton et al. (Infect. Immun. 77:3626-3638, 2009) reported that the Enterococcus faecalis ΔsrtA mutant forms significantly reduced (∼60%, P = 0.0142) biofilm in comparison to that of wild-type E. faecalis strain OG1RF during growth under static and hydrodynamic conditions. This report prompted us to reinvestigate our previously published biofilm (grown using static conditions) and mouse urinary tract infection (UTI) data, where we reported that a ΔsrtA mutant showed only ∼5% reduction (but significant) in biofilm in comparison to wild-type E. faecalis OG1RF. We found that our freezer vial of the ΔsrtA mutant was contaminated with wild-type E. faecalis OG1RF cells. We then repeated both the biofilm and the mouse UTI experiments with OG1RF-free ΔsrtA mutant cells and found no difference in log10 CFU recovery at kidney and UTI bladder infection sites in monoinfection experiments (at 104 inocula), consistent with our published results. However, the decrease in biofilm seen with the contaminant-free ΔsrtA mutant (Fig. 1) was much more substantial, with the median optical density at 570 nm (OD570) of the ΔsrtA mutant 48% less than that of the wild type (P = 0.0017), much closer to the reduction reported by Guiton et al.; the results for the Δbps and ΔsrtA Δbps mutants were similar to those in our original paper. These results indicate that the previous report of only a slight decrease in biofilm was due to the inadvertent contamination of the ΔsrtA mutant with wild-type OG1RF. We regret this unfortunate error.
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