Abstract：
Enterococcus faecalis is a Gram-positive bacterium that is frequently found in the periapical lesion of patients with apical periodontitis. Its biofilm formation in root canal is closely related to the development of refractory apical periodontitis by providing increased resistance to endodontic treatments. Phage therapy has recently been considered as an efficient therapeutic strategy in controlling various periodontal pathogens. We previously demonstrated the bactericidal capacities of Enterococcus phage vB_EfaS_HEf13 (phage HEf13) against clinically-isolated E. faecalis strains. Here, we investigated whether phage HEf13 affects biofilm formation and pre-formed biofilm of clinically-isolated E. faecalis, and its combinatory effect with endodontic treatments, including chlorhexidine (CHX) and penicillin. The phage HEf13 inhibited biofilm formation and disrupted pre-formed biofilms of E. faecalis in a dose- and time-dependent manner. Interestingly, phage HEf13 destroyed E. faecalis biofilm exopolysaccharide (EPS), which is known to be a major component of bacterial biofilm. Furthermore, combined treatment of phage HEf13 with CHX or penicillin more potently inhibited biofilm formation and disrupted pre-formed biofilm than either treatment alone. Confocal laser scanning microscopic examination demonstrated that these additive effects of the combination treatments on disruption of pre-formed biofilm are mediated by relatively enhanced reduction in thickness distribution and biomass of biofilm. Collectively, our results suggest that the effect of phage HEf13 on E. faecalis biofilm is mediated by its EPS-degrading property, and its combination with endodontic treatments more potently suppresses E. faecalis biofilm, implying that phage HEf13 has potential to be used as a combination therapy against E. faecalis infections.
摘要：
粪肠球菌是一种革兰氏阳性细菌，常见于根尖周炎患者的根尖病变中。它在根管中的生物膜形成与难治性根尖周炎的发展密切相关，因为它增加了对牙髓治疗的抵抗力。噬菌体疗法最近被认为是控制各种牙周病原体的有效治疗策略。我们先前证明了肠球菌噬菌体vB_EfaS_HEf13(噬菌体HEf13)对临床分离的粪肠球菌菌株的杀菌能力。这里,我们调查了噬菌体HEf13是否影响临床分离的粪肠球菌的生物膜形成和预先形成的生物膜，以及它与牙髓治疗的联合作用，包括氯己定（CHX）和青霉素。噬菌体HEf13以剂量和时间依赖性方式抑制粪肠球菌的生物膜形成和破坏预先形成的生物膜。有趣的是,噬菌体HEf13破坏粪肠球菌生物膜胞外多糖(EPS)，已知是细菌生物膜的主要组成部分。此外，噬菌体HEf13与CHX或青霉素联合治疗比单独治疗更有效地抑制生物膜形成和破坏预先形成的生物膜。共聚焦激光扫描显微镜检查表明，组合处理对预形成的生物膜破坏的这些加性效应是由生物膜的厚度分布和生物量的相对增强的减少介导的。总的来说，我们的结果表明，噬菌体HEf13对粪肠球菌生物膜的作用是由其EPS降解特性介导的，并且其与牙髓治疗的组合更有效地抑制粪肠球菌生物膜，这意味着噬菌体HEf13有潜力用作针对粪肠球菌感染的联合疗法。
