PCR-based characterization of nasal and ocular surface flora and functional analysis of bacterial metabolic pathways in congenital nasolacrimal duct obstruction

To evaluate the role of Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, Serratia marcescens, and Moraxella catarrhalis in the nasal and ocular surface flora, along with their metabolic activities in children with unilateral congenital nasolacrimal duct obstruction (CNLDO).

Swabs were taken from the bilateral inferior meatus and ocular surface of 26 children with unilateral CNLDO before probing. Nasal and ocular surface swabs from non-operated eyes of children who underwent unilateral blepharoptosis or strabismus surgery formed the control group. The quantitative polymerase chain reaction (qPCR) method was used to analyze the samples.

The detection of Streptococcus pneumoniae in the nasal flora, Staphylococcus aureus in the ocular surface flora, and Haemophilus influenzae and Serratia marcescens in both the nasal and ocular surface flora was higher on the obstructed sides of children with CNLDO compared to the controls (p < 0.05). Obstructed sides in children with CNLDO showed a significant difference for Moraxella catarrhalis in the ocular surface and Streptococcus pneumoniae, Staphylococcus aureus, Serratia marcescens, and Moraxella catarrhalis in the nasal flora compared to the patent sides (p < 0.05). Metabolite analysis revealed that betaine, L-carnitine, L-leucine, and L-alanine were negatively regulated in the presence of these bacteria.

Significant changes in bacterial composition in the nasal and ocular surface flora may be a cause or a result of CNLDO. More comprehensive microbiological studies that evaluate the entire microbiome would be helpful in understanding CNLDO.