Evaluation of the antibacterial activity of Lactobacilli probiotics supernatants against Enterococcus faecalis (in-vitro study)

BACKGROUND: There is an increasing demand to find a potent antibacterial agent against endodontic pathogens with the least toxic effect. The study aimed to evaluate the antibacterial activity of Lactobacilli probiotics on Enterococcus faecalis (E. faecalis) in comparison to calcium hydroxide paste. METHODS: The study involved two stages; (stage one): determination of the antibacterial properties of three strains of Lactobacilli probiotics supernatants (PS); Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacillus acidophilus, and a cocktail mix of the three supernatants against E. faecalis using agar well diffusion method in both solution and gel phase. The formed zones of inhibition (ZOI) were measured in millimeters (mm) and compared to each other. PS solution and gel of the largest ZOI were further compared with calcium hydroxide paste (35% Ultra Cal XS Ca(OH)(2)) This was followed by (stage two): assessment of the minimum inhibitory concentration (MIC) of the PS that showed the largest ZOI against E. faecalis by agar well diffusion assay for both PS solution and gel. RESULTS: All supernatants showed growth inhibition against E. faecalis, and the cocktail mix showed the largest ZOI. However, no significant difference was found between the supernatants in both the solution and gel phases (p > 0.05). Ca(OH)(2) showed a significantly lower effect than both the cocktail mix solution and gel (p < 0.05). The MIC of the cocktail mix solution and gel against E. faecalis was 50 mg/ml. (p > 0.05). CONCLUSION: PS has an antibacterial effect on E. faecalis and was more effective than Ca(OH)(2.) Lactobacilli probiotics could be a promising antibacterial agent used as an irrigant or an intracanal medication.