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Jane Gilmore, Coby Ray, Declan Kirk, Keaton Luth, Phat Tran, David McCartney, Kelly Mitchell, Ted W Reid; The Normal Human Ocular Microbiome Derived From Meta-analysis Methodology. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3687.
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The aim of the study is to utilize meta-analysis methodology to identify the normal human ocular microbiome based on the conglomeration of all applicable studies reported in the literature to date.
A systematic literature review in the PubMed/MEDLINE, OVID, and EMBASE databases revealed 294 papers pertinent to our search methods. Utilizing criteria to exclude any studies involving non-humans, non-healthy eyes and/or patients, lack of species specific culture data, and/or studies not reporting bacterial species identified through culture methods, the resulting 80 studies were included in our final analysis. The culture results for healthy human eyes were combined based on relative frequency and a generalizable normal ocular flora was amalgamated. Additional data such as study design, methods, geography, and clinical area was also recorded and utilized for sub-group analysis.
The combined papers produced a study population of 30,574 participants with 38,106 total swabs (eyes) yielding 26,185 positive culture results. 21% of studies were from the US with 29% in Asia, 24% in Europe, and the remainder in South America, the Middle East, Australia, Canada and Africa. Based on these papers, we were able to tabulate and combine the culture results of conjunctival swabs performed on normal-healthy individuals to identify a generalizable “normal” ocular flora. The top 4 bacterial families were Bacillaceae (48.8%), Actinomycetaceae (26.5%), Corynebacteriaceae (10.4%), and Staphylococcaceae (7.8%). The top 5 species were Staphylococcus spp (39.5%), Corynebacterium xerosis (19.3%), Propionibacterium spp (9.3%), Corynebacterium spp (7.1%), and Streptococcus spp (6.2%).
Based on the large number of unique culture incidences (62,413) included in our meta-analysis, we are confident concluding the normal ocular flora of a healthy human adult includes Staphylococcus spp, Corynebacterium xerosis, Propionibacterium spp, Corynebacterium spp, Streptococcus spp, and yet there are multiple other bacteria that appear inconsistently and require further study. We are also confident in stating there is clearly a geographic variation based on where an individual lives.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Distribution of normal ocular flora (shown as phylum) by geographical regions
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