Enterococcus faecalis is a major opportunistic bacterial pathogen of increasing clinical relevance. A substantial body of experimental evidence suggests that early biofilm formation plays a critical role in these infections, as well as in colonization and persistence in the GI tract as a commensal member of the microbiome in most terrestrial animals. Animal models of experimental endocarditis generally involve inducing mechanical valve damage by cardiac catheterization prior to infection, and it has long been presumed that endocarditis vegetation formation resulting from bacterial attachment to the endocardial endothelium requires some pre-existing tissue damage. Here we review both historical and contemporary animal model studies demonstrating the robust ability of E. faecalis to directly attach and form stable microcolony biofilms encased within a bacterially-derived extracellular matrix on the undamaged endovascular endothelial surface. We also discuss the morphological similarities when these biofilms form on other host tissues, including when E. faecalis colonizes the GI epithelium as a commensal member of the normal vertebrate microbiome - hiding in plain sight where it can serve as a source for systemic infection via translocation. We propose that these phenotypes may allow the organism to persist as an undetected infection in asymptomatic individuals and thus provide an infectious reservoir for later clinical endocarditis.

中文翻译：

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肠球菌性心内膜炎：隐藏在普通视线中。

粪肠球菌是临床相关性日益增加的主要机会性细菌病原体。大量实验证据表明，早期生物膜形成在这些感染以及作为大多数陆生动物微生物组共生成员的胃肠道中的定植和持久性中起着关键作用。实验性心内膜炎的动物模型通常涉及在感染前通过心导管插入术诱导机械瓣膜损伤，并且长期以来一直假设由细菌附着到心内膜内皮导致的心内膜炎赘生物形成需要一些预先存在的组织损伤。在这里，我们回顾了历史和当代动物模型研究，证明了大肠杆菌的强大能力。粪便直接附着并形成稳定的微菌落生物膜，包裹在未受损的血管内皮表面上的细菌衍生的细胞外基质中。我们还讨论了当这些生物膜在其他宿主组织上形成时的形态相似性，包括当粪肠球菌作为正常脊椎动物微生物群的共生成员定植于胃肠道上皮时——隐藏在显眼的地方，它可以通过易位作为全身感染的来源. 我们提出这些表型可能使该生物体在无症状个体中作为未被发现的感染持续存在，从而为以后的临床心内膜炎提供传染源。我们还讨论了当这些生物膜在其他宿主组织上形成时的形态相似性，包括当粪肠球菌作为正常脊椎动物微生物群的共生成员定植于胃肠道上皮时——隐藏在显眼的地方，它可以通过易位作为全身感染的来源. 我们提出这些表型可能使该生物体在无症状个体中作为未被发现的感染持续存在，从而为以后的临床心内膜炎提供传染源。我们还讨论了当这些生物膜在其他宿主组织上形成时的形态相似性，包括当粪肠球菌作为正常脊椎动物微生物群的共生成员定植于胃肠道上皮时——隐藏在显眼的地方，它可以通过易位作为全身感染的来源. 我们提出这些表型可能使该生物体在无症状个体中作为未被发现的感染持续存在，从而为以后的临床心内膜炎提供传染源。