Comparison of ocular microbiomes between patients with and without dry eye

Objective

To explore the difference in ocular surface microbiota between patients with and without dry eye.

Methods

Forty-two patients (42 eyes) diagnosed with dry eye were enrolled as dry eye group in the First Affiliated Hospital of Xi’an Jiaotong University from June to November 2020, and 37 controls without dry eye (37 eyes) were enrolled as control group in the same period.One eye was selected as the study eye, and the right eye was included when both eyes met the inclusion criteria.Swab samples from the conjunctival sac were obtained and sequenced.Sequencing of the V3-V4 region of the bacterial 16S rRNA gene was performed with Miseq PE301+ 8+ 301 platform.Operational taxonomic species (OTUs) clustering of microflora, comparison of alpha and beta diversity analysis of microflora between the two groups, annotation analysis of species and analysis of microbial markers were performed.The study protocol was approved by the Ethics Committee of The First Affiliated Hospital of Xi’an Jiaotong University (No.XJTU1AFCRC2018SJ-014). Written informed consent was obtained from each subject before any medical examination.

Results

A total of 18 586 OTUs were obtained, and 3 674 OTUs were shared between the two groups.Alpha diversity analysis showed that there was no significant difference in observed species index, Chao index, Ace index, Shannon index and Simpson index between the two groups (all at P>0.05), suggesting there was no difference in microbiota richness between them.The PCoA analysis showed that the microbial compositions of the two groups were significantly different (R²=0.039, F=3.100, P=0.022). The dominant flora of the two groups was similar, with Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes and Cyanobacteria as the top 5 abundant bacterial phyla, with Pelomonas, Corynebacterium, Propionibacterium, Pseudomonas and Herbaspirillum as the top 5 bacterial genera.LEfSe analysis identified Tissierellaceae, Enhydrobater and Finegoldia as dominant bacterial genera in dry eye group, and Caulobacter and Curvibacter in control group.

Conclusions

The composition of ocular surface microbiomes is different between dry eye patients and controls.

Dry eye; Ocular microbiomes; 16S rRNA gene amplicon sequencing