Probiotic bacteria reduce damages of pretreated epithelial corneal cells due to pathogens infections

Aims: the aim of this study was to evaluate the protective effect of probiotic strains on pretreated human corneal epithelial cells (HCE) infected by Staphylococcus aureus and Pseudomonas aeruginosa. Methods: the bacterial strains used were probiotics Lactobacillus reuteri DSM20016 and Bifidobacterium longum subsp. infantis DSM20088, and pathogens S. aureus ATCC 6538 and P. aeruginosa ATCC 9027. Pretreatment of HCE with each probiotic strain at 24 h prior to S. aureus or P. aeruginosa inoculation followed by 24 h of growth in combination was performed. Cytotoxicity, anti-inflammatory and anti-nitrosative activities of each probiotic strain in combination with each pathogen were compared to those of pathogen alone. Results: the pretreatment with probiotic strains significantly protected HCE cells against infection. L. reuteri and B. longum showed ability to adhere to HCE cells, increase viability and demonstrated to reduce anti-inflammatory and anti-nitrosative biomarkers associated to infection. Conclusion: the topical administration of probiotic strains could prevent the severity of the recurrent keratitis caused by S. aureus and P. aeruginosa and to avoid corneal ulceration.