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Jerome Ozkan, Mark Willcox, Bernd Wermeuer, Torsten Thomas, Minas T Coroneo; What is hiding in your eyes? The microbiome of ocular surface niches. Invest. Ophthalmol. Vis. Sci. 2018;59(9):908. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Numerous regions of the body contain infolded regions (or crypts), which act as unique habitats for microbial communities. Knowledge of whether microorganisms are able to reside in protected niches of the conjunctiva is potentially significant in terms of minimising risks of contact lens-related inflammation/infection, exogenous endophthalmitis and potentially understanding idiopathic ocular surface disorders with an inflammatory component (including dry eye syndrome, episcleritis, chronic follicular conjunctivitis). In this study, we aim to define if and how microbial communities of limbal and forniceal crypts differ from those on the conjunctival surface.
Normal human limbal and conjunctival forniceal tissue was obtained from 23 patients undergoing pterygium surgery and surface swabs of conjunctival surface were obtained from 45 individuals. Microbial communities were analysed by extracting total DNA from tissue samples and surface swabs and sequencing the 16S rRNA gene using the Illumina MiSeq platform. Sequences were quality filtered, clustered into operational taxonomic units (OTUs) at 97% similarity using USEARCH and then taxonomically classified. Fluorescent in situ hybridization (FISH) was then used to visualize specific bacteria on cryosections (7 µm) of limbal and conjunctival forniceal tissue.
There was a significant difference in bacterial community structure between the conjunctival surface and forniceal (PERMANOVA P=0.001) or limbal (PERMANOVA P=0.001) tissue. There was no difference in the bacterial communities between the limbus and fornix (PERMANOVA P=0.401). Fornix and limbal samples were dominated by OTUs classified to the genus Pseudomonas (relative abundance 75.0%), which were only found in low relative abundances on conjunctival surfaces (10.4%). Application of FISH found Pseudomonas in the forniceal tissue sample.
Our results show that there are discrete tissue-associated microbiome in protected crypt space of the eye. The finding that these protected niches are dominated by Pseudomonas may have implications for contact lens wear and ocular surgery.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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