Do Oral Pathogens Inhabit the Eye and Play a Role in Ocular Diseases?

Abstract

Fascinatingly, the immune-privileged healthy eye has a small unique population of microbiota. The human microbiome project led to continuing interest in the ocular microbiome. Typically, ocular microflorae are commensals of low diversity that colonize the external and internal sites of the eye, without instigating any disorders. Ocular commensals modulate immunity and optimally regulate host defense against pathogenic invasion, both on the ocular surface and neuroretina. Yet, any alteration in this symbiotic relationship culminates in the perturbation of ocular homeostasis and shifts the equilibrium toward local or systemic inflammation and, in turn, impaired visual function. A compositional variation in the ocular microbiota is associated with surface disorders such as keratitis, blepharitis, and conjunctivitis. Nevertheless, innovative studies now implicate non-ocular microbial dysbiosis in glaucoma, age-related macular degeneration (AMD), uveitis, and diabetic retinopathy. Accordingly, prompt identification of the extra-ocular etiology and a methodical understanding of the mechanisms of invasion and host-microbial interaction is of paramount importance for preventative and therapeutic interventions for vision-threatening conditions. This review article aims to explore the current literature evidence to better comprehend the role of oral pathogens in the etiopathogenesis of ocular diseases, specifically AMD.

Interactions between systemic diseases and oral microbiota shifts in the aging community: A narrative review

“…Low levels of oral Lactococcus also imply that microbial dysbiosis plays a part in the pathogenesis of GM [85]. The significantly higher oral bacterial load observed in GM patients revealed that constant exposure to bacterial products in GM patients exacerbates the severity/progression of the disease [162].…”

Ocular Surface Microbiome: Influences of Physiological, Environmental, and Lifestyle Factors

“…A "core" microbiota, consisting of a few taxa, is shared among all individuals [20], encompassing commensal, environmental, and potentially pathogenic bacteria [21]. The predominant phyla observed on the OS include Proteobacteria, Actinobacteria, and Firmicutes [11,12,22,23,24,25,26,27,28]. At the genus level, commonly found taxa comprise Pseudomonas, Propionibacterium, Bradyrhizobium, Corynebacterium, Acinetobacter, Brevundimonas, Staphylococci, Aquabacterium, Sphingomonas, Streptococcus, Streptophyta, and Methylobacterium.…”

Molecular Characterization of Bacterial Agents Causing External Ocular Infections Isolates of Patients in a Third Level Hospital

“…Detecting the specific aetiological agent, as well as understanding the ocular microbiota and its relationship with the host and the patient's comorbidities, allows for optimal management of these infections [10][11][12]. Gram-positive bacteria are the main contributors to bacterial eye infections, such as Staphylococcus aureus and coagulase-negative Staphylococcus, where some species belonging to the skin microbiota are found, e.g., S. epidermidis and S. saprophyticus [13,14].…”