Conjunctival Sac Microbiome in Infectious Conjunctivitis

Abstract

Background To determine the conjunctival bacterial community among the infectious conjunctivitis cases attending the outpatient clinic of Khanh Hoa General Hospital in Nha Trang, Vietnam from October 2016 through December 2017. Of all, 50 randomly selected samples using a computer generated random number list were included for microbiome identification. Conjunctival swabs were collected and tested using conventional culture, PCR, and 16S ribosomal RNA sequencing. Results The study included randomly selected 47 patients. More than 98% of all DNA reads represented five bacterial phyla. Three of these phyla constitute 92% of all sequences [Firmicutes (35%), Actinobacteria (31%), and Proteobacteria (26%)]. At the genus level, there were twelve common genera constituted about 61% of all the sequence reads. Seven of those genera were common [Streptococcus (10%), Cutibacterium (10%), Staphylococcus (7%), Nocardioides (7%), Corynebacterium 1 (5%), Anoxybacillus (5%), and Acinetobacter (5%)], which encompassed 49% of all reads. As for diversity analysis, there was no difference in PERMANOVA analysis (Unweighted UniFrac) for sex (P = 0.087), chemosis (P = 0.064) and unclassified eyedrops (P = 0.431). There was no difference in PERMANOVA analysis for pain (P = 0.315) and itching (P = 0.133). There was a statistical significant difference in cases with bilateral conjunctivitis (P = 0.017) and for using antibiotics (P = 0.020). Conclusion Firmicutes among the predominant phyla has the highest abundance in bacterial conjunctivitis in our study. Pseudomonas as a resident commensal microbiota has an important role for prevention of infection.