Effect of xylitol on mutans streptococci and lactic acid formation in saliva and plaque from adolescents and young adults with fixed orthodontic appliances

This study aimed to investigate two dose regimens of xylitol-containing tablets on the ecology of dental plaque and saliva during treatment with fixed orthodontic appliances. The study group comprised 56 healthy patients (mean age 15.8 yr) randomly assigned into the following groups: A, (n = 23) two xylitol tablets two times a day (1.7 g xylitol d(-1)) for 18 wk; B, (n = 23) two tablets four times per day (3.4 g xylitol d(-1)) for 18 wk; and C, (n = 10) no tablets. The levels of mutans streptococci (ms) were enumerated in plaque and saliva and the proportion of xylitol-sensitive (X(S)) strains in saliva was determined by autoradiography with [(14)C]-xylitol at baseline and at 6, 12, and 18 wk. The lactic acid formation rate was assessed enzymatically in sucrose-challenged plaque suspensions. A drop in salivary ms levels was found in Group A after 6 wk but not after 12 or 18 wk. The proportion of X(S) ms was decreased after 6 wk in groups A and B and remained so during the experimental period. The lactic acid formation rates decreased slightly ( approximately 10%) in the two xylitol groups compared with baseline. In conclusion, our results showed that although an alteration of ms strains was demonstrated following a regular daily low-dose intake of xylitol, the long-term total ms counts in plaque and saliva as well as plaque acidogenicity remained unchanged.     

Aminopeptidase activity in strains of oral streptococci

Ten strains of oral streptococci were analyzed for aminopeptidase activity by isoelectric focusing and crossed immunoelectrophoresis together with enzyme staining procedures. Substrate specificities were determined using 15 aminoacyl-β-naphthylamides. All 10 strains tested showed enzyme activity with the arginine and leucine substrates. None of the strains exhibited activity with the glycine, cystine, or proline substrates. Some strains had multiple enzyme bands with some of the substrates. All strains had aminopeptidase bands located in the pi range 4.1–4.3, except Streptococcus mutans IB and Streptococcus milleri NCTC 10708. The isoelectric profiles of these strains, having enzyme bands in the range 4.45–4.9, differed markedly from the others. These were also the only strains where no arginine aminopeptidase cross-reactivity occurred with the Streptococcus mitis ATCC 903 antiserum.     

Penicillin-induced lysis in related species of oral streptococci

Treatment of 10 strains representing 5 species of related oral streptococci with penicillin G resulted in measurable levels of cellular lysis. This lysis was dependent on penicillin concentration and cell density. At similar penicillin concentrations and cell densities, the 10 strains demonstrated appreciable differences in their lytic responses. Lysis values for Streptococcus mutans (GS-5 and Ingbritt) and Streptococcus rattus (BHT and FA-1) were greater than those for Streptococcus sobrinus (01 and B13), Streptococcus cricetus (HS6 and AHT), and Streptococcus ferus (8S1 and HD3).     

Effects of xylitol and fluoride on the response to glucose pulses of Streptococcus mutans T8 growing in continuous culture

Streptococcus mutans T8 was grown glucose-limited at pH 7.0 in a chemostat and pulsed, under pH free-fall conditions, with glucose, xylitol or a mixture of the two. Experiments were conducted in the absence or continual presence of low levels (1 mmol.l-1) of fluoride. Culture filtrates of samples taken at frequent intervals were assayed for carbohydrate and fermentation end-products. Fluoride had little effect on the organism's response to glucose until the culture pH fell to ca. 5.0, at which point the rate of lactate production was reduced some 3-fold. Xylitol affected the response to glucose but its effect was most marked in the presence of fluoride. Under these conditions, the rate of lactate production was reduced at least 3-fold, the pH did not fall to 5.0 and only about 50% of the added glucose was consumed. This suggests that xylitol can augment the metabolic effects on S. mutans of low levels of fluoride.     

Effects of xylitol, xylitolsorbitol, and placebo chewing gums on the plaque of habitual xylitol consumers

Xylitol reduces plaque but the reduction mechanism is largely unknown. The main aim of the present study was to determine whether the xylitol-induced reduction in the amount of plaque and the number of mutans streptococci could be demonstrated in subjects with (presumably) high levels of xylitol-resistant (X^R; not inhibited by xylitol) mutans streptococci acquired following previous xylitol consumptions. 37 healthy dental students participated in the double-blind study. All subjects had been uncontrolled, habitual consumers of xylitol-containing products for at least 1 yr before the study, A 1-month washout period was followed by a 2-week test period during which either xylitol, xylitol-sorbitol or unsweetened chewing gum base was chewed 3–5 × a day. Plaque and saliva samples were collected at baseline and at the 2-week point for determination of the amount of plaque, microbiological variables, and hydrolytic enzymes. Mixtures of xylitol and sorbitol seemed to perform equally well with respect to reduction in the amount of plaque but not the number of mutans streptococci. Thus, polyols were the active ingredients of chewing gums able to modulate the amount of plaque and its microbial composition. Xylitol reduced plaque with a mechanism which appeared not to be associated with the study-induced changes in the proportion (%) of mutans streptococci in plaque, the number of salivary mutans streptococci, the proportion of X^R strains in plaque or saliva, or the hydrolytic enzyme activities of plaque.     

Membrane locus and pH sensitivity of paraben inhibition of alkali production by oral streptococci

Parabens were found to be potent inhibitors of alkali production from arginine by oral streptococci such as Streptococcus rattus, Streptococcus sanguis and Streptococcus gordonii. For example, 2 mumol butylparaben per ml completely and irreversibly inhibited arginolysis by intact cells of S. rattus FA-1 and was lethal for the organism. In contrast, butylparaben was not a very effective inhibitor of ureolysis by intact cells of Streptococcus salivarius 57.I, although it did kill the cells. Butylparaben irreversibly inhibited the cytoplasmic enzymes arginine deiminase, carbamate kinase and urease in permeabilized cells or isolated form. However, inhibition of arginolysis by intact cells appeared to be due primarily to irreversible inhibition of transport systems for arginine uptake, because butylparaben added to intact cells did not reduce levels of arginine deiminase when the cells were subsequently permeabilized after washing. The insensitivity of ureolysis by intact cells to butylparaben can be related to the known high permeability of cell membranes to urea and the cytoplasmic location of urease. The potency of butylparaben as an inhibitior of arginolysis or glycolysis and as a lethal agent was found to be greater at acid pH that at neutral or alkaline pH.     

Bactericidal action of tachyplesin I against oral streptococci

Tachyplesin I, a polycationic antimicrobial peptide isolated from hemocytes of horseshoe crabs, kills bacteria by disrupting the membrane potential of the cytoplasmic membrane. The present study shows that, among 36 oral streptococcal strains, 12 of 21 Streptococcus sanguis , 3 Streptococcus mutans , 9 Streptococcus salivarius and 3 Streptococcus milleri strains were susceptible to tachyplesin I, whereas 9 S. sanguis strains were resistant. Interestingly, these resistant strains include the clinical isolates from both Kawasaki disease and Behget patients. According to the time-kill study, tachyplesin I inhibited irreversibly the growth of S. sanguis. S. tuutans and S. salivarius strains within 20 min and an S. milleri strain within 20 min. Although it has been suggested that Escherichia coli cultured in rich media were more susceptible to tachyplesin I, the present results show thai only 3 S. milleri strains were more sensitized to tachyplesin I in a glucose-supplemented medium, and other tested strains were not. Similarly, only 4 strains were more resistant to tachyplesin I in saline than these were in a rich medium.     

Ecology of viridans streptococci in the oral cavity and pharynx

Recently published taxonomic studies of viridans streptococci have resulted in several changes in the nomenclature and definition of oral streptococcal species. With this background, the ecology of streptococci in the oropharyngeal cavities was reinvestigated. The results based on the examination of 1426 streptococcal isolates confirmed and extended earlier findings. Apart from mature supragingival plaque, which contained a mixture of all orally encountered streptococci, each site showed a characteristic streptococcal flora. Initial dental plaque formation is primarily associated with Streptococcus sanguis, Streptococcus mitis biovar 1 and Streptococcus oralis. Our investigation showed that S. sanguis and S. mitis biovar 1 were the most prominent streptococci, also on buccal mucosa. In contrast, S. oralis was almost exclusively found in initial dental plaque. Streptococcus gordonii, formerly part of S. sanguis, was found in small numbers on the oropharyngeal mucosa and in mature supragingival plaque. The dorsum of the tongue was dominated by S. mitis biovar 2 and Streptococcus salivarius, the latter of which was predominant also on the pharyngeal mucosa. Streptococcus anginosus was by far the most predominant streptococcus in subgingival plaque. Immunoglobulin A1 (IgA1) protease-producing streptococci were primarily isolated from initial dental plaque and from the buccal mucosa. This lends further support to the concept of IgA1 proteases being important for the ability of streptococci to evade the local immune defence during their initial colonization of certain oral surfaces.     

Glucosyltransferase production by Streptococcus sanguis Challis and comparison with other oral streptococci

Glucosyltransferase (GTF) activity in batch cultures of Streptococcus sanguis strain Challis in defined medium was maximum at peak growth and declined rapidly on further incubation into stationary phase. Activity was present in spent culture medium and was associated with 2 polypeptides of approximate Mrs 170 kDa (90% of activity) and 155 kDa (about 10% of activity). Other S. sanguis strains produced similar antigenically-related polypeptides but with varying activities, and antibodies to the S. sanguis enzyme did not react with enzymes produced by other species of oral streptococci. Increasing the [Na+] reduced GTF production by S. sanguis strains Challis and NCTC 7865, and by Streptococcus sobrinus, but not by Streptococcus salivarius. Addition of Tween 80 to cultures caused a rapid inhibition of GTF synthesis by strain Challis, but not by strain NCTC 7865. Benzyl alcohol had a slower and less inhibitory effect on GTF production by strain Challis. Tween 80 generally inhibited to varying degrees GTF production by other oral streptococci through in S. sobrinus it was stimulated. The results suggest controls operating on GTF synthesis and secretion by different strains of oral streptococci appear to be diverse.     

Effect of inorganic ions and surface active organic compounds on the adherence of oral streptococci

abstract — A reduction in the adherence of oral streptococci was observed after topical application of aluminum ions to standardized dentin test pieces whereas pyrophosphate and tripolyphosphate seemed to inhibit the adherence after incorporation in the incubation solution. A pronounced effect was recorded after topical application of surfactants with the positively charged primary amino group as end group. Hydrofluorides of several such aliphatic amines effectively reduced the number of colony-forming units washed off from the test pieces. Also the free base of hexadecylamine showed a similar effect. Inhibition of adherence was also obtained with long chain esters of lysine, with an optimum at 16 carbon atoms in the alcohol group. These compounds have the advantage of being built up from molecules known to the body.     

Effect of low-molecular-weight chitosans on the adhesive properties of oral streptococci

It was previously shown that a low-molecular-weight chitosan and its derivatives N-carboxymethyl chitosan and imidazolyl chitosan inhibit Streptococcus mutans adsorption to hydroxyapatite. The ability of the same molecules to interfere with adhesive properties of other oral streptococci (Streptococcus sanguis, Streptococcus gordonii, Streptococcus constellatus, Streptococcus anginosus, Streptococcus intermedius, Streptococcus oralis, Streptococcus salivarius, Streptococcus vestibularis) was tested. When saliva-coated or -uncoated hydroxyapatite beads were treated with N-carboxymethyl chitosan, a reduction varying from 60% to 98% depending on strains was observed. Low-molecular-weight chitosans and imidazolyl chitosan did not have any effect. Growth in N-carboxymethyl chitosan-supplemented medium (final concentrations ranging from 20 to 500 micrograms.ml-1) caused a dose related reduction in the adsorption of all strains to hydroxyapatite and in their affinity towards xylene. No effect was observed with low-molecular-weight chitosans and imidazolyl chitosan. In contrast to what observed with S. mutans, the three polysaccharides did not affect detachment from hydroxyapatite beads and adherence to cheek epithelial cells of the other streptococci. These results suggest that low-molecular-weight chitosans and/or imidazolyl chitosan, selectively affecting S. mutans adsorption to hydroxyapatite, may be very interesting as potential anti-dental caries agents.     

Effect of xylitol gum on the level of oral mutans streptococci of preschoolers: block-randomised trial

Objectives: To assess the influence of xylitol chewing gum consumption on mutans streptococci level of 3–4 years old Japanese preschoolers. Methods: 248 participants were examined regarding caries‐related factors at baseline and were followed up at 6, 9, and 12 months after the baseline: assessors were blinded, subjects were open labelled and blocked parallel randomised; 142 were selected to use xylitol gum for 3 months (from months 6 to 9) and 106 were controls. Results: 161 participants were analysed (xylitol n = 76, control n = 85). Nineteen caries‐related variables, including xylitol gum consumption, were analysed for any association with the main outcome, plaque mutans streptococci scores development within the intervention period, by logistic regression. Six showed statistically significant associations by univariate analysis (P < 0.05). However, only xylitol gum consumption remained a significant negative association (P < 0.05) by multiple analyses. Interestingly, over 10% xylitol group children experienced diarrhoea, which was larger than previous investigations. Conclusion: Xylitol gum is effective in avoiding increased plaque mutans streptococci in young children.     

Interference of oral hygiene products with an adhesion-based assay of salivary mutans streptococci

Abstract – The effect of several oral hygiene products on an adhesion-based assay for salivary mutans streptococci (Dentocult-SM Strip Mutans) was studied in three women. The mutans streptococci levels were recorded for up to 24 h after a 1-min rinse with the product. The chlorhexidine (0.05%) and stanno-amine fluoride solutions (corresponding 0.025% F) interfered selectively with the adhesion-based assay. No such effect was observed for a polyvidoneiodine solution (10 μg/ml) or two toothpastes containing either sodium lauryl sulfate or amine fluorides. The results indicate that antimicrobial agents showing retention in the oral cavity may interfere for several hours after their use with adhesion-based assays of salivary mutans streptococci.     

Antimicrobial activity of garlic against oral streptococci

Abstract:  The antimicrobial activity of two garlic clones' (1: purple and 2: white) crude extracts against oral microbiota was evaluated in vitro (study 1) and in vivo (study 2). Study 1 consisted of the evaluation of minimum inhibitory (MIC) and bactericidal (MBC) concentrations against nine streptococci strains. In study 2, a 2.5% garlic (clone 2) solution was used as a mouthwash in a 5-week study by 30 subjects. Blood agar and Mitis Salivarius Bacitracin agar were inoculated with subjects' saliva to quantify oral microorganisms and mutans streptococci. Study 1 showed MIC ranging from 0.5 to 32.0 mg ml⁻¹ for clone 2 and from 8 to 64.0 mg ml⁻¹ for clone 1. MBC ranged from 1.0 to 128.0 mg ml⁻¹ and from 8.0 to 128.0 mg ml⁻¹ regarding clones 2 and 1 respectively. Study 2 showed that 2.5% garlic mouthwash solution had good antimicrobial activity against mutans streptococci and oral microorganisms. Maintenance of reduced salivary levels of streptococci was observed after 2 weeks at the end of mouthwash use. Unpleasant taste (100%), halitosis (90%) and nausea (30%) were reported by subjects after the end of the study. It was concluded that the garlic clones have antimicrobial properties in vitro against streptococci and anticariogenic properties against oral microorganism in spite of its adverse effects.     

口腔链球菌对伴放线嗜血菌生长影响的体外实验

目的：研究变异链球菌、血链球菌、远缘链球菌、唾液链球菌对伴放线嗜血菌生长的影响。方法：制备伴放线嗜血菌BHI琼脂板,将4种口腔链球菌菌悬液滴注于其上,兼性厌氧培养48h,观察有无抑菌现象。分别将4种口腔链球菌与伴放线嗜血菌等体积等浓度混合制成双菌种悬液在液体BHI中培养,每隔4h取浮游菌悬液梯度稀释,接种于BHI琼脂板上培养48h,计数伴放线嗜血菌占菌落总数的百分比：扫描电镜观察双菌种生物膜生长情况。结果：琼脂扩散实验显示,变异链球菌、血链球菌、远缘链球菌周围出现抑菌圈,唾液链球菌周围未出现抑菌圈。伴放线嗜血菌所占双菌种混合细菌的比例随时间延长呈下降趋势（p〈0．05）。生物膜观察显示,单菌种伴放线嗜血菌形成生物膜的时间较口腔链球菌时间长;双菌种混合培养时伴放线嗜血菌的量随时间推移而减少。结论：4种口腔链球菌抑制伴放线嗜血菌生长。     

Effects of frequent mouthrinses with palatinose and xylitol on dental plaque

The aim was to evaluate the effects of frequent mouthrinses with palatinose, xylitol and a mixture of palatinose and xylitol on plaque pH, plaque formation and cariogenic microorganisms. 15 subjects refrained from toothbrushing during 3 test periods and rinsed 15 × daily for 4 d with 10 nil of: (1) 50% palatinose, (2) 37.5% palatinose+ 12.5% xylitol, or (3) 50% xylitol. A contrast period with no mouthrinses was also carried out. The 4 periods were carried out in a randomized order with a cross–over design. After the 4–day periods, 3 parameters were measured: (1) plaque pH during the first 30 min after a mouthrinse with palatinose, a mixture of palatinose and xylitol or xylitol alone, directly followed by a 2nd rinse with 10% sucrose; (2) number of mutans streptococci and lactobacilli in plaque and saliva; (3) plaque index. The most pronounced pH drop for the sugar substitutes was found when rinsing with 50% palatinose after the palatinose period, and the least pH drop with 50% xylitol after the xylitol period. The sucrose rinse gave similar pH fall after all 4 periods. The microbial data showed no differences between the 4 periods, but the mutans streptococcus counts in saliva decreased after the xylitol period in contrast to the 3 other periods. Regarding the plaque index, xylitol gave lower scores compared to the other 3 periods.     

Inhibitory effects of cranberry juice on attachment of oral streptococci and biofilm formation

Cranberry juice is known to inhibit bacterial adhesion. We examined the inhibitory effect of cranberry juice on the adhesion of oral streptococci strains labeled with [3H]-thymidine to saliva-coated hydroxyapatite beads (s-HA). When the bacterial cells were momentarily exposed to cranberry juice, their adherence to s-HA decreased significantly compared with the control (P < 0.01). Their hydrophobicity also decreased dependently with the concentration of cranberry juice. We also evaluated the inhibitory effect of cranberry juice on biofilm formation. By using a microplate system, we found that the high molecular mass constituents of cranberry juice inhibited the biofilm formation of the tested streptococci. The inhibitory activity was related to the reduction of the hydrophobicity. The present findings suggest that cranberry juice component(s) can inhibit colonization by oral streptococci to the tooth surface and can thus slow development of dental plaque.     

Classification of oral streptococci by two-dimensional gel electrophoresis with direct activity stain for glycosyltransferases

Thirty eight strains of oral streptococci were divided into six types by two-dimensional gel electrophoresis (2-DE) followed by glycosyltransferase (GLT) activity stain: Type 1, Streptococcus mutans; Type 2, Streptococcus rattus; Type 3, Streptococcus sobrinus and Streptococcus downei; Type 4, Streptococcus cricetus; Type 5, Streptococcus salivarius; and Type 6, Streptococcus sanguis, Streptococcus oralis and Streptococcus gordonii. In Types 1, 2 and 5, two glucosyltransferases synthesizing water-insoluble (GTF-I) and water-soluble glucans (GTF-S) and a fructosyltransferase (FTF) were detected. In Types 3 and 4, GTF-I and two GTF-Ss were detected. Only one GTF-S was detected in Type 6. The 2-DE patterns for these six types were clearly distinguished from each other based on the kind, number and location of GLTs in gel.     

口腔链球菌右旋糖酐酶分子结构和功能的研究进展

右旋糖酐酶是一种葡聚糖酶,主要降解α-1,6葡聚糖,能够水解水溶性多糖,广泛存在于自然界中。很多细菌包括口腔链球菌在内都能够合成右旋糖酐酶。口腔链球菌合成的右旋糖酐酶与胞外多糖的修饰以及细菌的黏附有关。本文主要对近年来口腔链球菌右旋糖酐酶的分子结构及其功能的研究进行综述。     

Salivary mutans streptococci and dental caries in three-year-old children after maternal exposure to chewing gums containing combinations of xylitol,sorbitol, chlorhexidine,and fluoride

The aim of this study was to evaluate the effect of maternal use of chewing gums containing combinations of xylitol, sorbitol, chlorhexidine, and fluoride on salivary mutans streptococci (MS) counts and caries prevalence in the mothers' 3-year-old children. After screening 416 women with newborn babies, 173 mothers with high counts of salivary MS were randomly assigned into 3 experimental chewing gum groups containing (A) xylitol (n=61), (B) chlorhexidine/xylitol/sorbitol (n=55), and (C) sodium fluoride/xylitol/sorbitol (n=57). Mothers with low or medium MS counts formed a reference group (D) without any intervention (n=232). The participants in the experimental groups were instructed to chew one piece of the gum for 5 min 3 times a day. The chewing regimen started when the child was 6 months old and was terminated 1 year later. The outcome measures were salivary MS counts and caries prevalence at the age of 3 years. Bacterial enumeration was carried out with a chair-side technique and caries (defs) was scored by clinical examination. Medium and high counts of salivary MS were found in 13%, 16%, and 22% in groups A, B, and C, respectively. The mean defs was 0.1 in group A, 0.2 in group B, and 0.4 in group C. The differences concerning salivary MS and caries were not statistically significant. The MS counts and caries prevalence in children of mothers with low MS counts (group D) were similar to those found in groups A and B. In conclusion, lower but non-significant levels of salivary MS and dental decay were observed in 3-year-old children to mothers who used high-content xylitol gums compared with those who used lower amounts of xylitol. The efficiency of this type of targeted intervention in a low-caries community may be questioned.