The Gram-positive bacterium Enterococcus faecalis and the fungus Candida albicans are both found as commensals in many of the same niches of the human body, such as the oral cavity and gastrointestinal (GI) tract. However, both are opportunistic pathogens and have frequently been found to be coconstituents of polymicrobial infections. Despite these features in common, there has been little investigation into whether these microbes affect one another in a biologically significant manner. Using a Caenorhabditis elegans model of polymicrobial infection, we discovered that E. faecalis and C. albicans negatively impact each other's virulence. Much of the negative effect of E. faecalis on C. albicans was due to the inhibition of C. albicans hyphal morphogenesis, a developmental program crucial to C. albicans pathogenicity. We discovered that the inhibition was partially dependent on the Fsr quorum-sensing system, a major regulator of virulence in E. faecalis. Specifically, two proteases regulated by Fsr, GelE and SerE, were partially required. Further characterization of the inhibitory signal revealed that it is secreted into the supernatant, is heat resistant, and is between 3 and 10 kDa. The substance was also shown to inhibit C. albicans filamentation in the context of an in vitro biofilm. Finally, a screen of an E. faecalis transposon mutant library identified other genes required for suppression of C. albicans hyphal formation. Overall, we demonstrate a biologically relevant interaction between two clinically important microbes that could affect treatment strategies as well as impact our understanding of interkingdom signaling and sensing in the human-associated microbiome.

Background:Acute ruptures of the ulnar collateral ligament (UCL) of the thumb are common injuries in sports. Surgical repair has yielded excellent results and high return-to-sport (RTS) rates in elite athletes.Purpose:To determine (1) the RTS rate in Major League Baseball (MLB) players following thumb UCL repair, (2) postoperative career length and games played per season, (3) pre- and postoperative performance, (4) postoperative performance compared with matched control players, and (5) whether dominant and nondominant hand injuries respond differently.Study Design:Cohort study; Level of evidence, 3.Methods:MLB players who underwent thumb UCL surgery from August 3, 1987, to September 6, 2016, were identified. Demographic and performance data were collected for each player, and matched controls were identified. RTS in the MLB was defined as playing in at least 1 MLB game after surgery. Comparisons were made by use of paired-samples Student t tests.Results:Twenty-one players were identified, with a mean ± SD age of 31.7 ± 3.9 years and mean experience in the MLB of 8.6 ± 3.3 years at time of surgery. Twenty-one players (100%) achieved RTS in the MLB at a mean 120.0 ± 75.9 days. No significant decrease was found in games per season or career length for any position following surgery. Infielders had a significantly lower rate of postoperative wins above replacement (WAR) compared with preoperatively (P = .006), but no significant differences in postoperative performance score were found compared with controls after the index date. No significant difference was found for performance between players undergoing surgery on their dominant hand and those who had surgery on their nondominant (glove) hand compared with controls.Conclusion:In this study, 100% of MLB players achieved RTS after thumb UCL repair, with in-season players returning at a mean of 8 weeks. Players who underwent thumb UCL repair played in a similar number of games per season and had similar career lengths in the MLB as controls. Infielders had a significantly lower postoperative WAR compared with preoperatively, but no significant postoperative performance score differences were noted when infielders were compared with post–index date matched controls. No significant performance differences were noted with regard to surgery on dominant and nondominant hands.

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