Anticariogenic and antibiofilm of purified bacteriocin of Lactobacillus curvatus and immunomodulatory effect of L. curvatus in streptococcal bacteremia

Streptococcus mutans and Streptococcus sanguinis have been associated with the development of caries, oral infections and bacteremia. In fact, there are only a few case reports in the literature describing bacteremia in relation to S. mutans and S. sanguine . The objective of this study was purification and characterization of curvatcin LHM from Lactobacillus curvatus , evaluation of its antibacterial activity against S. mutans and S. sanguinis and evaluation the effect of minimum inhibitory concentration of curvatcin LHM and chlorohexidine on biofilm formation as well as, study the effect of L. curvatus as immunomodulator. Curvatcin LHM was isolated and purified from L. curvatus culture. Purified and crude curvatcin LHM exhibited bactericidal action against S. mutans and S. sanguinis isolates in vitro . Significant differences ( P  < 0.05) were found in viable count between pre and posttreatment of S. mutans and S. sanguinis biofilms with curvatcin LHM and chlorohexidine. Unlike chlorohexidine, curvatcin LHM left no viable bacterial cells in biofilm of S. mutans and S. sanguinis . Bagg Albino laboratory breed (BALB/c) mice were orally administered with L. curvatus for 2 weeks and then intravenously injected with S. mutans and S. sanguinis . Four days before inoculation, microbiological and immune response were determined, serum proinflammatory cytokine, TNF-α, IL-10 and IL-6 were evaluated by ELISA. The L. curvatus treatment significantly decreased S. mutans and S. sanguinis in the organs and blood of mice with bacteremia as compared with the non- L. curvatus -treated mice ( P  < 0.05). Furthermore, proinflammatory cytokine, TNF-α, IL-10 and IL-6, were significantly higher in groups pretreated with L. curvatus ( P  < 0.05) prior streptococcal infection. These data suggest that curvatcin LHM may be a good alternative to chlorhexidine as an additive for teeth-protective materials. Curvatcin LHM cotreatment with chlorohexidine might help to increase the anticariogenic efficacy of chlorohexidine. On the other hand, L. curvatus can be serving as direct modulator of proinflammatory responses.