TOPICAL APPLICATION OF LACTOBACILLUS REUTERI IN PREVENTION AND MANAGEMENT OF STAPHYLOCOCCUS AUREUS CORNEAL INFECTION

Background and Aims. The topical application of lactic acid bacteria (LAB) is recognized as potential management tools to improve epithelial and mucosal barrier functions in various disease states by suppressing inflammatory responses, decreasing oxidative stress and keeping immune effects [1]. This study aims to evaluate the beneficial effects of the topical application of Lactobacillus reuteri in the prevention and management of Staphylococcus aureus keratitis. Methods. An in vitro model using human corneal epithelial (HCE) cells was employed. The strains used were L. reuteri DSM20016 and S. aureus ATCC 6538. Bacterial antagonism, cytotoxicity, anti-inflammatory and antinitrosative activity were evaluated by pretreatment of HCE cells with L. reuteri at 24 h prior to S. aureus inoculation followed by 24 h of growth in combination [2]. In another set of experiment, a wound healing in vitro model was performed by scraping confluent cell monolayers with a pipette tip. L. reuteri DSM20016 (107 UFC/ml) and S. aureus ATCC 6538 (104 UFC/ml) were then coincubated for 24 h. Along with the analyses mentioned above, mitochondrial activity was also evaluated [3]. Results and Conclusions. Pre-treatment with L. reuteri preserved HCE cell viability and conferred protection against S.aureus infection by exhibiting anti-inflammatory and antinitrosative properties. L. reuteri significantly reduced TNF-α and IFN-γ levels, while restoring IL-4 and IL-10 levels (p ≤ 0.001). Additionally, L. reuteri decreased NOx production (p ≤ 0.001), alleviating nitrosative stress. In the wound healing model, L. reuteri treatment accelerated infected wound closure. Moreover, L. reuteri decreased inflammation caused by S. aureus. In detail, L. reuteri significantly reduced TNF-α and IFN- levels, whereas IL-4 and IL-10 levels were increased (p ≤ 0.001). In addition, a decrease in NOx amount (p ≤ 0.001) and mitochondrial dysfunction was observed following L. reuteri treatment. The survival of S. aureus or its biofilm production ability were not affected at all by L. reuteri presence. In conclusion, this study demonstrates that L. reuteri exerts protective effects in the prevention and management of S. aureus-induced keratitis by reducing inflammation, nitrosative stress, and mitochondrial dysfunction, while accelerating wound healing.