Polymerase chain reaction based characterization of nasal and ocular flora microbiome in congenital nasolacrimal duct occlusion and functional analysis of microbiome related metabolic pathways

Objective: To characterize Streptococcus pneumonia, Staphylococcus aureus, Hemophilus influenza, Serratia marcescens, and Moraxella catarrhalis in the nasal and ocular surface flora of children with unilateral congenital nasolacrimal duct obstruction (CNLDO) using polymerase chain reaction (PCR)-based methods, and to identify the bioactivity and enzymes of these bacteria, and to compare age- and sex-matched healthy children. Materials and methods: Before probing, the swab samples were taken from the bilateral inferior meatus and ocular surfaces of 26 patients with unilateral CNLDO. Also, samples taken from the contralateral ocular surface and inferior meatus of the children who underwent unilateral strabismus or ptosis surgery constituted the control group. The presence and quantity of bacteria in the samples were analyzed by using primers specific to the bacteria. The cycle threshold (Ct) value was used to determine the amount of bacteria. The lower Ct value means there was more bacteria DNA/RNA in the sample. Results: Streptococcus pneumonia in nasal flora, Staphylococcus aureus in the ocular surface flora, and Hemophilus influenza, Serratia marcescens in both the nasal and ocular surface flora were more abundant on the CNLDO side than the control group (p<0.05). The ct value for all bacteria was lower on the CNLDO side in both nasal and ocular flora compared to controls (p<0.05). The difference was the most remarkable for Serratia marcescens. When the obstructed and patent sides of the children with CNLDO were compared, Moraxella catarrhalis was found to be higher in the ocular surface, and Streptococcus pneumoniae, Staphylococcus aureus, Serratia marcescens, Moraxella catarrhalis were found to be higher in the nasal flora (p<0.05). The metabolite analysis of these bacteria revealed that betaine, L-carnitine, L-leucine, and L-alanine were negatively regulated in the presence of these bacteria. Conclusion: CNLDO seems to be associated with some bacteria or alterations in their amounts in the ocular surface and nasal flora. These microbiological differences may be a risk factor for or a result of CNLDO.