Effects of Xylitol and Sucrose Mint Products on Streptococcus mutans Colonization in a Dental Simulator Model.

Few laboratory methods exist for evaluating the cariogenicity of food ingredients. In this study, a dental simulator was used to determine the effects of commercial sucrose and xylitol mint products on the adherence and planktonic growth of Streptococcus mutans. Solutions (3% w/v) of sucrose, xylitol, sucrose mints, xylitol mints, xylitol with 0.02% peppermint oil (PO), and 0.02% PO alone were used to test the levels of planktonic and adhered S. mutans. A dental simulator with continuous artificial saliva flow, constant temperature, and mixing was used as a test environment and hydroxyapatite (HA) discs were implemented into the model to simulate the tooth surface. Bacterial content was quantified by qPCR. Compared with the artificial saliva alone, sucrose and sucrose mints increased the numbers of HA-attached S. mutans, whereas xylitol decreased them. Similarly, planktonic S. mutans quantities rose with sucrose and declined with xylitol and xylitol mints. Versus sucrose mints, xylitol mints significantly reduced the counts of HA-bound and planktonic S. mutans. Similar results were observed with the main ingredients of both types of mints separately. PO-supplemented artificial saliva did not influence the numbers of S. mutans that attached to HA or planktonic S. mutans compared with artificial saliva control. In our dental simulator model, xylitol reduced the counts of adhering and planktonic S.mutans. The mints behaved similarly as their pure, main ingredients-sucrose or xylitol, respectively. PO, which has been suggested to have antimicrobial properties, did not influence S. mutans colonization.

Bifidobacterium animalis subsp. lactis BB-12 in reducing the risk of infections in early childhood.

BACKGROUND: Specific probiotic bacteria have proven to be effective in the prevention and treatment of infectious diseases in early life in at-risk populations. The impact of administration of Bifidobacterium animalis subsp. lactis BB-12 (BB-12) on the risk of acute infectious diseases was studied in healthy children. METHODS: In this double-blind, placebo-controlled study, 109 1-mo-old infants were assigned randomly to a probiotic group receiving a BB-12-containing tablet (n = 55) or a placebo (n = 54). Test tablets were administered to the infants twice a day (daily dose of BB-12 10 billion colony-forming units) until the age of 2 y with a novel slow-release pacifier or a spoon. Breastfeeding habits, pacifier use, dietary habits, medications, and all signs and symptoms of acute infections were registered in diaries by parents and in questionnaires by trained professionals. RESULTS: The infants receiving BB-12 were reported to have experienced fewer respiratory tract infections (RTIs; 87 vs. 100%; risk ratio: 0.87; 95% confidence interval: 0.76, 1.00; P = 0.033) than the controls. No significant differences between the groups were observed in reported gastrointestinal symptoms, otitis media, or fever. The baseline characteristics of the two groups were similar, as was the duration of breastfeeding. CONCLUSION: Administration of BB-12 in early childhood may reduce RTIs.

Effects of Lactobacillus reuteri PTA 5289 and L. paracasei DSMZ16671 on the adhesion and biofilm formation of Streptococcus mutans.

Probiotics have decreased the counts of salivary mutans streptococci (MS) in clinical studies. The aim of this study was to compare the effects of Lactobacillus reuteri PTA 5289 and L. paracasei DSMZ16671 on the adhesion of a reference strain and a clinical isolate of Streptococcus mutans and on the counts of MS in a biofilm. The adhesion of S. mutans Ingbritt and the clinical isolate S. mutans 2366 to a smooth glass surface and saliva-coated hydroxyapatite (SHA) were studied in the presence of and without the lactobacilli. A three-species biofilm formed on saliva-coated hydroxyapatite discs was used in the biofilm experiments. The lactobacilli did not affect adhesion to the glass surface but interfered with binding to SHA. No effects of the lactobacilli were detected on the MS levels in the three-species biofilms. The results of the SHA binding experiments best reflected the results of the existing clinical studies.

Effects of xylitol on xylitol-sensitive versus xylitol-resistant Streptococcus mutans strains in a three-species in vitro biofilm.

We studied the effects of xylitol on biofilms containing xylitol-resistant (Xr) and xylitol-sensitive (Xs) Streptococcus mutans, Actinomyces naeslundii and S. sanguinis. The biofilms were grown for 8 and 24 h on hydroxyapatite discs. The viable microorganisms were determined by plate culturing techniques and fluorescence in situ hybridization (FISH) was performed using a S. mutans-specific probe. Extracellular cell-bound polysaccharides (EPS) were determined by spectrofluorometry from single-species S. mutans biofilms. In the presence of 5 % xylitol, the counts of the Xs S. mutans decreased tenfold in the young (8 h) biofilm (p < 0.05) but no effect was seen in the mature (24 h) biofilm. No decrease was observed for the Xr strains, and FISH confirmed these results. No differences were detected in the EPS production of the Xs S. mutans grown with or without xylitol, nor between Xr and Xs S. mutans strains. Thus, it seems that xylitol did not affect the EPS synthesis of the S. mutans strains. Since the Xr S. mutans strains, not inhibited by xylitol, showed no xylitol-induced decrease in the biofilms, we conclude that growth inhibition could be responsible for the decrease of the counts of the Xs S. mutans strains in the clinically relevant young biofilms.

Probiotic lactobacilli interfere with Streptococcus mutans biofilm formation in vitro.

In clinical studies, probiotic bacteria have decreased the counts of salivary mutans streptococci (MS). We compared the effects of probiotic Lactobacillus strains on the biofilm formation of Streptococcus mutans. The bacterial strains used included four S. mutans strains (reference strains NCTC 10449 and Ingbritt and clinical isolates 2366 and 195) and probiotic strains Lactobacillus rhamnosus GG, L. plantarum 299v, and L. reuteri strains PTA 5289 and SD2112. The ability of MS to adhere and grow on a glass surface, reflecting biofilm formation, was studied in the presence of the lactobacilli (LB). The effect of LB culture supernatants on the viability of the MS was studied as well. All of the LB inhibited the biofilm formation of the clinical isolates of MS (P < 0.001). The biofilm formation of the reference strains of MS was also inhibited by the LB, but L. plantarum and L. reuteri PTA 5289 showed a weaker inhibition when compared to L. reuteri SD2112 and L. rhamnosus GG. Viable S. mutans cells could be detected in the biofilms and culture media only when the experiments were performed with the L. reuteri strains. The L. reuteri strains were less efficient in killing the MS also in the tests performed with the culture supernatants. The pHs of the supernatants of L. reuteri were higher compared to those of L. rhamnosus GG and L. plantarum; P < 0.001. In conclusion, our results demonstrated that four commonly used probiotics interfered with S. mutans biofilm formation in vitro, and that the antimicrobial activity against S. mutans was pH-dependent.

Xylitol and erythritol decrease adherence of polysaccharide-producing oral streptococci.

Xylitol consumption decreases counts of mutans streptococci. However, the mechanism behind this decrease is not well understood. We studied not only type strains and clinical isolates of mutans streptococci, but also other polysaccharide-forming oral streptococci. Growth inhibition and adherence of cells to a smooth glass surface-reflecting synthesis of water-insoluble polysaccharides were studied in the presence of 2% (0.13 mol/l) and 4% (0.26 mol/l) xylitol. The effect of xylitol was compared to a novel polyol sweetener, erythritol. Except for Streptococcus mutans 10449 and S. sobrinus OMZ 176, the glass surface adhesion of most polysaccharide-forming streptococci was reduced by the presence of both 4% xylitol and erythritol. For the S. mutans and S. sobrinus type strains, the growth inhibition with 4% xylitol and erythritol was 36-77% and for the clinical S. mutans isolates 13-73%. Of the other oral streptococci, only S. sanguinis was inhibited with 4% xylitol (45-55%). For both polyols, the magnitude of the growth inhibition observed was not associated with the magnitude of the decrease in adherence (xylitol: r = -0.18; erythritol: r = 0.49). In conclusion, both xylitol and erythritol can decrease polysaccharide-mediated cell adherence contributing to plaque accumulation through a mechanism not dependent on growth inhibition.

Growth inhibition of Streptococcus mutans with low xylitol concentrations.

No studies on the concentration dependency of the inhibition of Streptococcus mutans with xylitol are available. We studied xylitol-induced growth inhibition of two type strains, S. mutans NCTC 10449 and Ingbritt, and three clinical isolates of S. mutans. The strains were grown in Brain Hearth Infusion Medium in the presence of 0.001% (0.066 mM), 0.005% (0.33 mM), 0.01% (0.66 mM), 0.1% (6.6 mM), and 1% (66 mM) xylitol. Growth was followed by measuring the absorbance at a wavelength of 660 nm. The highest xylitol concentration tested in this study, 1%, showed mean inhibition percentages ranging from 61% to 76% when the growth inhibition of the five strains was compared to the control without xylitol at log-phase. For 0.1% xylitol, the inhibition percentages ranged from 22% to 59%. A concentration dependency was seen in the growth inhibition, with 0.01% xylitol being the lowest xylitol concentration inhibiting all five strains significantly (p < 0.001). The growth inhibition percentages determined for 0.01% xylitol, however, were low, and the inhibition was significantly weaker as compared to 0.1% and 1% xylitol. Our results suggest that low xylitol concentrations of 0.1% (6.6 mM) could inhibit mutans streptococci in vivo but even lower xylitol concentrations may be inhibitory.