Characteristics and associations of microbial community in the eye, anterior nares, and oropharynx of healthy adults: eye-nose microbiota transmission

Purpose: We compared the microbial communities of the eye, anterior nares (ANs) and oropharynx (OP) of healthy adults to provide a basic understanding of the microbial associations among the three sites.

Methods: The name of the registry of our prospective study was "Study on the diversity of microbial flora in the eye, nose and oropharynx of healthy people". The trial number is ChiCTR2300067724 (https://www.chictr.org.cn/index.aspx). Swabs were collected from the eye, ANs and OP of 48 healthy adult participants for 16S rRNA gene amplicon sequencing. The bacterial community profiles and their functional associations were compared among the three sites.

Results: At a phylum level, the basic bacterial compositions in the eye and ANs were generally similar, and the predominant phyla were Actinobacteria, Proteobacteria and Firmicutes. In contrast, the OP microbiota was characterized by an increased abundance of Bacteroidetes. At a genus level, Corynebacterium, Cutibacterium and Staphylococcus were the most abundant in the eye and ANs. Prevotella-7, Alloprevatella, Haemophilus and Streptococcus were more abundant in the OP. Correlation analysis of the eye and ANs microbiota suggested that Cutibacterium and Micrococcus may migrate from the eye to nose (P < 0.05).

Conclusions: The bacterial flora composition and function predictions of eye and ANs were similar, but differed from those of the OP in healthy adults. The OP bacterial flora distribution was markedly different, showing characteristics similar to that of the digestive tract flora. Thus, the eye and ANs microorganisms may be related in healthy individuals. Cutibacterium and Micrococcus may migrate from the eye to the nose.