PDF(Pubmed)
Abstract：
Enterococcus faecalis is a common cause of healthcare-acquired bloodstream infections and catheter-associated urinary tract infections (CAUTIs) in both adults and children. Treatment of E. faecalis infection is frequently complicated by multi-drug resistance. Based on protein homology, E. faecalis encodes two putative hyaluronidases, EF3023 (HylA) and EF0818 (HylB). In other Gram-positive pathogens, hyaluronidases have been shown to contribute to tissue damage and immune evasion, but the function in E. faecalis has yet to be explored. Here, we show that both hylA and hylB contribute to E. faecalis pathogenesis. In a CAUTI model, ΔhylA exhibited defects in bladder colonization and dissemination to the bloodstream, and ΔhylB exhibited a defect in kidney colonization. Furthermore, a ΔhylAΔhylB double mutant exhibited a severe colonization defect in a model of bacteremia while the single mutants colonized to a similar level as the wild-type strain, suggesting potential functional redundancy within the bloodstream. We next examined enzymatic activity, and demonstrate that HylB is capable of digesting both hyaluronic acid (HA) and chondroitin sulfate in vitro, while HylA exhibits only a very modest activity against heparin. Importantly, HA degradation by HylB provided a modest increase in cell density during the stationary phase and also contributed to dampening of lipopolysaccharide-mediated NF-κB activation. Overall, these data demonstrate that glycosaminoglycan degradation is important for E. faecalis pathogenesis in the urinary tract and during bloodstream infection.
摘要：
粪肠球菌是成人和儿童医疗保健获得性血流感染和导管相关尿路感染（CAUTI）的常见原因。粪肠球菌感染的治疗经常因多重耐药性而复杂化。基于蛋白质同源性,粪肠球菌编码两种推定的透明质酸酶，EF3023(HylA)和EF0818(HylB)。在其他革兰氏阳性病原体中，透明质酸酶已被证明有助于组织损伤和免疫逃避，但是粪肠球菌的功能还有待探索。这里,我们表明hylA和hylB都有助于粪肠球菌的发病机制。在CAUTI模型中,ΔhylA表现出膀胱定植和向血流传播的缺陷，和ΔhylB表现出肾脏定植缺陷。此外，ΔhyLAΔhylB双突变体在菌血症模型中表现出严重的定植缺陷，而单个突变体定植到与野生型菌株相似的水平，提示血液中潜在的功能冗余。我们接下来检查了酶活性，并证明HylB能够在体外消化透明质酸（HA）和硫酸软骨素，而HylA对肝素仅表现出非常适度的活性。重要的是,HylB的HA降解在稳定期期间提供了细胞密度的适度增加，并且还有助于抑制脂多糖介导的NF-κB激活。总的来说,这些数据表明,糖胺聚糖降解对于泌尿道和血流感染期间的粪肠球菌发病机制是重要的。
