Background The purpose is to study the metagenomics of the microbes isolated from the lacrimal sac of patients with primary acquired nasolacrimal duct obstruction (PANDO).

Methods A prospective study was performed on ten consecutive lacrimal sac samples obtained for the metagenomic analysis from the patients with PANDO, who underwent endoscopic dacryocystorhinostomy at a tertiary care Dacryology service. The samples were collected intraoperatively soon after a full-length lacrimal sac marsupialisation and immediately transported on ice to the laboratory. Following DNA extraction and library preparation, a whole shotgun metagenome sequencing was performed on the Illumina platform. The downstream processing and bioinformatics of the samples were performed using multiple software packaged in the SqueezeMeta pipeline and MG-RAST pipeline.

Results The taxonomic hit distribution across the samples showed that bacteria were the most common isolates (mean—97.56%), followed by viruses (mean—0.29%), archaea (0.04%) and others. The five major phyla identified across the samples of PANDO were proteobacteria, Bacteroidetes, Fusobacteria, Actinobacteria and Firmicutes. The prevalent organisms include Acinetobacter johnsonii, Porphyromonas catoniae, Cutibacterium acnes, Pseudomonas alcaliphila, Escherichia coli, Haemophilus influenzae, Enhydrobacter aerosaccus, Fusobacterium nucleatum, Moraxella osloensis, Butyricimonas virosa and Variovorax paradoxus, among few others. The alpha diversity of the ten sample datasets ranged from 60 to 175 species.

Conclusion This is the first whole metagenome sequencing of the lacrimal sac contents from PANDO patients. Lacrimal sacs harbour diverse microbial communities, including bacteria, viruses, and archaea. Further Lacriome studies may provide clues for a better understanding of the disease aetiopathogenesis.