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PubMed2005

Transport and metabolism of citrate by Streptococcus mutans.

Streptococcus mutans, a normal inhabitant of dental plaque, is considered a primary etiological agent of dental caries. Two virulence determinants of S. mutans are its acidogenicity and aciduricity (the ability to produce acid and the ability to survive and grow at low pH, respectively). Citric acid is ubiquitous in nature; it is a component of fruit juices, bones, and teeth. In lactic acid bacteria citrate transport has been linked to increased survival in acidic conditions. We identified putative citrate transport and metabolism genes in S. mutans, which led us to investigate citrate transport and metabolism. Our goals in this study were to determine the mechanisms of citrate transport and metabolism in S. mutans and to examine whether citrate modulates S. mutans aciduricity. Radiolabeled citrate was used during citrate transport to identify citrate metal ion cofactors, and thin-layer chromatography was used to identify metabolic end products of citrate metabolism. S. mutans was grown in medium MM4 with different citrate concentrations and pH values, and the effects on the growth rate and cell survival were monitored. Intracellular citrate inhibited the growth of the bacteria, especially at low pH. The most effective cofactor for citrate uptake by S. mutans was Fe(3+). The metabolic end product of citrate metabolism was aspartate, and a citrate transporter mutant was more citrate tolerant than the parent.

Biological Transport↗
PubMed2004

Longitudinal study of transmission, diversity, and stability of Streptococcus mutans and Streptococcus sobrinus genotypes in Brazilian nursery children.

The aim of this study was to perform a follow-up evaluation of the Streptococcus mutans and Streptococcus sobrinus colonization profile of children's oral cavities, which included the pattern of vertical transmission from mother to child, genotypic diversity, and stability of the strains. The subjects were 16 mother-child pairs, who were monitored for 20 months. Samples of saliva, tongue dorsum, alveolar ridge mucosa, and dental plaque from the children were collected bimonthly. Saliva samples from the mothers were also collected. After isolation and identification, the arbitrarily primed PCR method was performed for the genotypic characterization of S. mutans (968 isolates) and S. sobrinus (111 isolates). At the time the strains were acquired, the children harbored one to four distinct genotypes of S. mutans and only one genotype of S. sobrinus. Although S. mutans prevalence and genotypic diversity were greater than those of S. sobrinus, the presence of matching genotypes of S. mutans and S. sobrinus was similar (in 81.25 and 83.33% of mother-child pairs, respectively), suggesting vertical transmission for both species. This longitudinal study showed an increase in genotypic diversity of S. mutans in the oral cavity during the follow-up period: most of the initially acquired genotypes persisted, normally those genotypes transmitted by the mother, and some were lost during follow-up; new strains were also acquired. In conclusion, S. mutans and S. sobrinus genotypes acquired from maternal or alternative sources may show effective persistence in the oral cavity and/or transitory detection in the children's mouths, reflecting the continuous development of oral microbiota in children.

Adult↗
PubMedDate not supplied

Inhibitory effects of oolong tea extract on caries-inducing properties of mutans streptococci.

The inhibitory effects of oolong tea extract (OTE) on the caries-inducing properties of mutans streptococci were examined in vitro. OTE reduced the rate of acid production by mutans streptococci accompanied with the retardation of growth rate of mutans streptococci, while the action by chromatographically isolated oolong tea polyphenol (OTF6) was weak. On the other hand, both oolong tea products decreased cell surface hydrophobicity of almost all the oral streptococci examined in the present study, and also induced cellular aggregation of Streptococcus mutans, Streptococcus oralis, Streptococcus sanguis or Streptococcus gordonii. In these reactions, OTF6 showed a more pronounced activity than OTE. Furthermore, the oolong tea products inhibited the adherence of mutans streptococci to saliva-coated hydroxyapatite. These results suggest that OTF6 may inhibit bacterial adherence to the tooth surfaces by reducing the hydrophobicity of mutans streptococci, and OTE may inhibit caries-inducing activity of mutans streptococci by reducing the rate of acid production.

Bacterial Adhesion↗
PubMedDate not supplied

Peroxidase reaction as a parameter for discrimination of Streptococcus mutans and Streptococcus sobrinus.

425 strains of mutans streptococci and 12 reference strains were investigated by membrane fatty acid spectra (MFAS) and peroxidase reaction (PR) after aerobic and anaerobic incubation. 423 strains were identified as Streptococcus mutans. The remaining 2 strains were identified as Streptococcus sobrinus. The PR of 29 strains was doubtful; immediately after anaerobic incubation a negative PR changed into a slightly positive PR. To test the diagnostic value of PR the strains were additionally investigated by means of species-specific polymerase chain reactions (PCR). The species-specific PCRs were developed on the basis of the respective genes of 16S rRNA of the pathogens S. mutans and S. sobrinus. Specificity and sensitivity were tested on reference strains (n = 17) and negative control strains (n = 39). The results of this investigation showed that an anaerobic incubation regime could lead to false-positive (S. mutans) or false-negative (S. sobrinus) PR. The 425 MS strains were classified as either S. mutans (n = 420) or S. sobrinus (n = 5). The findings on the reference strains required a reclassification of S. mutans V 100 into S. sobrinus V 100. Summarising, it is possible now to differentiate strains of mutans streptococci by MFAS and PR after aerobic incubation.

Aerobiosis↗
PubMedDate not supplied

Transmission of mutans streptococci in adults within a Chinese population.

The purpose of this study was to investigate whether there was transmission between adults in Chinese families using chromosomal DNA fingerprinting. Plaque samples were obtained from buccal and occlusal surfaces of 11 married couples. The colonization levels of mutans streptococci were estimated as colony-forming units per milliliter, and caries experience was scored by decayed, missing and filled teeth. Information about medical history, diet regimes and age at marriage was obtained. The isolates were serotyped by biochemical test and genotyped using the restriction endonuclease HaeIII. The procedure was repeated after 3 months. The results showed that 1 couple had the same genotype of mutans streptococcus at the first examination, but this could not be repeated for the husband who had lost his mutans streptococci at the second examination. On the contrary, another couple that did not have the same mutans streptococcal genotype at the beginning had the same genotype after 3 months. No matching of genotypes was observed within 8 couples. In 1 male, no mutans streptococci were detected, therefore that couple was not considered. These data indicate that spouses had a chance to be infected by strains of mutans streptococci from another person. The results suggest that there may be transmission between adults in Chinese families, but it may be difficult for mutans streptococci to colonize another mouth permanently.

Adult↗
PubMedDate not supplied

The persistence of Streptococcus mutans in nasopharyngeal carcinoma patients after radiotherapy.

The aim of the study was to examine the persistence of oral Streptococcus mutans in nasopharyngeal carcinoma patients after radiotherapy. Ten subjects, ranging in age from 20 to 67 years, participated. DMFT/DMFS, salivary level of mutans streptococci and oral health status were recorded. Pooled plaque samples were obtained from the cervical margins and the interproximal regions of all the teeth and the occlusal surfaces of the molars prior to, immediately after, 3 and 6 months after the completion of radiotherapy. At least 10 colonies of S. mutans were isolated from each subject and totally 645 isolates were genotyped by restriction endonuclease analysis. The results showed that the salivary level of S. mutans increased significantly with the reduction of salivary flow rate after radiotherapy. Each subject had at least 1 genotype of S. mutans isolated throughout the follow-up period. In 3 subjects who initially carried 2 or more genotypes, 1 or 2 genotypes of S. mutans could not be detected 3 months after treatment. Moreover, the genotypes that became undetectable were predominant bacteria in the first sampling. The result indicated that most S. mutans genotypes were persistent after radiotherapy but some genotypes that might not adapt to the alteration of oral environment became undetectable.

Adult↗
PubMed2006

Influence of a fluoride mouthrinse on mutans streptococci in schoolchildren.

This study aimed to determine whether the long-term use of a fluoride mouthrinse affects the salivary levels of mutans streptococci. Two hundred and fifteen schoolchildren (aged 9-10 years) participated. One hundred and forty-nine of these children had used a fluoride mouthrinse since 5 years of age at nursery school, and the remaining 66 children had not. DFT (decayed and filled teeth) was recorded, and the salivary levels of Streptococcus mutans and Streptococcus sobrinus were measured using mitis salivarius bacitracin agar. The group that had used a fluoride mouthrinse had a significantly lower prevalence of both S. mutans and S. sobrinus (p = 0.038) and a significantly lower DFT score (p < 0.001) than the other group. Using logistic regression analysis including caries experience at baseline as a dependent variable, the odds ratio of carrying S. mutans alone was 8.0 (p = 0.066) and that of carrying both S. mutans and S. sobrinus was 16.5 (p = 0.022) in the group that had not used the fluoride mouthrinse. Children carrying both S. mutans and S. sobrinus had a higher caries incidence in 1 year than the others, with odds ratios of 5.73 (p = 0.067) in the group with a fluoride mouthrinse and 3.47 (p = 0.035) in the group without it. These results show that the long-term use of a fluoride mouthrinse is associated with reduced salivary levels of mutans streptococci and this bacterial reduction may partly contribute to the suppression of dental caries in children using a long-term fluoride mouthrinse.

Cariostatic Agents↗
PubMed1989

Streptococcus mutans infection level and caries in a group of 5-year-old children.

The level of Streptococcus mutans in stimulated saliva and its association with caries experience was evaluated in 149 5-year-old children. In general, salivary S. mutans levels were low, and it was detected only in 46% of saliva samples. There was, however, a clear association between salivary levels of S. mutans and caries experience (chi 2 = 53.65, p less than 0.001). Salivary examination was supplemented with plaque samples in 47 children. The number of S. mutans positive surfaces increased with increasing salivary levels. S. mutans was most often isolated and comprised the highest proportion in the approximal samples. The number of children with high salivary S. mutans levels was very low (6%) when taken into account that 13% of the children were fairly caries active (dmfs greater than or equal to 5). This most probably means that in evaluation of caries risk, the salivary S. mutans screening level is different in preschool children and in older children. The level should be determined in longitudinal studies before applying to preschool children.

Bacteriological Techniques↗
PubMed1990

A method for the identification of Streptococcus mutans in gingival margin plaque by immunofluorescence.

A method was developed to identify Streptococcus mutans in natural dental plaque by indirect immunofluorescence staining, using a high-titred polyclonal antiserum raised against a serotype c strain of S. mutans followed by an FITC conjugate. Specificity was determined by staining 45 representative strains of plaque organisms, which demonstrated minimal cross-reactions. In vitro incubation of S. mutans NCTC 10449 films with a human serum containing antibodies to S. mutans and the presence of extracellular polysaccharide did not inhibit staining. The staining method enabled 98% of the streptococci to be detected in mixtures of S. mutans NCTC 10449 and Lactobacillus casei NCTC 10302. S. mutans was detected at a ratio of 1:100,000 in mixtures of pure cultures. In plaque samples, S. mutans could be distinguished from other organisms, including an unidentified cross-reacting bacillus found in some gingival plaque samples. The results suggest that immunofluorescence is a fast, practical method for identifying specific bacteria in plaque and, therefore, could be of use in microbiological studies of caries.

Animals↗
PubMed1991

Long-term xylitol consumption and mutans streptococci in plaque and saliva.

The effect of 4 to 6 years of habitual use of xylitol gum (greater than or equal to 2 times per day) on the viable counts of mutans streptococci in both plaque and saliva was evaluated in a cross-sectional study of participants of the Ylivieska xylitol study (Finland, 1982-1984). Paraffin-stimulated saliva was collected first, whereafter the remaining plaque was collected from all available tooth surfaces and pooled. The habitual xylitol consumers (n = 15) had less plaque than the controls (n = 21). The total viable counts of mutans streptococci in the plaque collected from the habitual xylitol users were about 10% of those determined in controls (p less than 0.01). The salivary mutans streptococci levels were relatively high in both habitual xylitol consumers and controls, as determined using a plate count and with an adhesion-based assay; no significant differences were detected between these groups. Thus, habitual xylitol consumption appeared not to be associated with a reduction in the total numbers of mutans streptococci in saliva. The plaque and the mutans streptococci were, however, more loosely bound to the tooth surfaces of the habitual xylitol users. The results of the plate count and the adhesion-based assay for salivary mutans streptococci were in good agreement for both habitual xylitol consumers and the controls. This suggests that it was the accumulation of plaque rather than the adhesiveness of mutans streptococci that was affected by the habitual consumption of xylitol.

Adolescent↗
PubMed1992

Viability of Streptococcus mutans and Streptococcus sobrinus in whole saliva with varying concentrations of indigenous antimicrobial agents.

We have studied the possible relationship between indigenous salivary antimicrobial agents, indigenous mutans streptococci and the capability of added mutans streptococci to grow in saliva. Stimulated whole saliva was collected from 19 healthy donors. Saliva samples were sterilized, supplemented with glucose and inoculated with Streptococcus mutans or Streptococcus sobrinus. The mixtures were incubated for 20 h followed by counting of viable cells. Saliva samples were analysed, both before and after sterilization, for indigenous antimicrobial agents and the bacterial flora. The subjects could be divided into two groups: those (n = 9) whose saliva promoted and those (n = 10) whose saliva inhibited the growth of the inoculated streptococci. A statistically significant correlation (+0.82, p < 0.001) was found between the numbers of viable cells of S. mutans and S. sobrinus after incubation in saliva. The sterilization procedure reduced the content of all antimicrobial proteins. Salivary antimicrobial factors, or levels of indigenous mutans streptococci, did not differ between the two groups. We conclude that none of the individual salivary antimicrobial factors alone can explain the large individual differences in growth-promoting or growth-inhibiting patterns of saliva on S. mutans and S. sobrinus. Inter-individually, saliva either supports or inhibits the growth of mutans streptococci, indicating a similar response of these two species in relation to the properties of saliva.

Adult↗
PubMed1994

Mutans streptococci in a Thai population: relation to caries and changes in prevalence after application of fissure sealants.

The aims of this study were to evaluate the level of mutans streptococci in two groups of Thai (Bangkok) children; to relate the findings to caries prevalence and to the caries increment over 2 years, and to study whether different sealant and fluoride programmes affected levels of mutans streptococci over a 2-year period. The baseline survey comprised 1,114 children aged 12 years. For the sealant project, a minimum of three caries-free permanent molars was required; 752 children aged 12-13 and 512 children aged 7-8 years were distributed into five groups: control group, Delton fissure sealant group, glass ionomer fissure sealant applied by dentist (GIC-dentist group) or by school teachers given a 3-day course (GIC-teacher group), and an HF group (0.5% HF solution applied 3 times). The WHO standard criteria were used to record caries. Prevalence of mutans streptococci was estimated using the Strip mutans test. Mean DMFT (n = 1,114) of 12-years-olds was 2.96; 17% had Strip mutans class 0 (low level), 32% class 1, 33% class 2 and 18% class 3 (the corresponding mean DFT +/- SD for each mutans streptococci class was 1.84 +/- 2.33, 2.23 +/- 2.14, 3.18 +/- 2.75, and 3.59 +/- 3.01 respectively). For the 7- to 8-year-olds (n = 512), mean df teeth at baseline was 5.36 (d = 5.19; f = 0.17); 5% had Strip mutans class 0, 17% class 1, 33% class 2 and 45% class 3 (the corresponding mean df teeth was 3.19 +/- 2.5, 4.13 +/- 2.84, 4.89 +/- 2.94 and 6.39 +/- 3.16 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2001

Association of Streptococcus mutans infection and oral developmental nodules in pre-dentate infants.

Since dental caries may present soon after tooth eruption, we hypothesized that colonization of Streptococcus mutans can occur in the predentate stages. In this study, we examined S. mutans colonization and its association with oral developmental nodules (Bohn's nodules) in 60 pre-term and 128 full-term, three-month-old infants. Overall, S. mutans was cultured from 30% (56/188) of the infants, and oral developmental nodules were noted in 55% (103/188). Compared with the pre-term, full-term infants showed a higher prevalence of S. mutans (34% vs. 20%, p < 0.02) as well as developmental nodules (61% vs. 42%, p < 0.05). In both groups, S. mutans was positively associated with numbers of developmental nodules in a dose-response relationship (p < 0.001), and with maternal salivary levels of the bacteria (p = 0.03). The permanence of S. mutans infection was confirmed by repeat saliva sampling at 6 months of age. Our results thus showed that many infants have already acquired S. mutans at 3 months of age, prior to tooth eruption.

Alveolar Process↗
PubMed1976

Purification, characterization, and immunogenicity of cell-associated glucan from Streptococcus mutans.

Appropriate immunization with whole cell vaccines of S mutans appear to induce antibodies that inhibit implantation of S mutans on tooth surfaces and associated dental caries. To better understand the mechanisms by which vaccination prevents S mutans implantation and dental caries, and to prepare antigens whose effectiveness and safety can be tested in animal models of caries, we set out to purify and chemically characterize the CAG of S mutans. The CAG of S mutans strain 6715 was prepared by extracting cells with potasssium hydroxide at 100 C. After neutralization and extensive washing, the water-insoluble product was characterized by a battery of chemical analyses and found to be a relatively pure glucan. The CAG was weakly immunogenic in rabbits when administered in Freund's complete adjuvant. In monkeys (M irus) immunized via the parotid duct with an aqueous solution of CAG, a definite but weak serum IgG, IgM, IgA, and salivary IgA antibody response was observed. Absorption experiments showed that the CAG induced antibodies that cross reacted with Sephadex G-25 and others that reacted with unique determinants on CAG. Retention of native antigenic determinants through the purification procedures was verified by the observations that antiserums to CAG reacted with whole cells of S mutans and by the fact that antiserums to S mutans cells reacted with CAG.

Animals↗
PubMed1976

Streptoccus mutans dextransucrase: purification, properties, and requirement for primer dextran.

We attempted to purify dextransucrase from S mutans strain 6715 to investigate its properties and determine if multiple species of the enzyme existed. It was concluded that the properties of this enzyme such as the pH (5.5), temperature (37 C) optimum, and Km for sucrose (3 mM) are very similar to those reported for S sanguis, S bovis, S mutans strain OMZ-176 isozymes, S mutans strain GS-5, and the single dextransucrase purified from S mutans strain HS-6. The IEF enzyme preparation consisted of two enzyme species, possibly differing in their ability to synthesize different dextran linkages. The minor enzyme activity demonstrated a strict primer dependency. Similarly, primer dependency has been reported for dextransucrases from S mutans, S sanguis, and L mesenteroides. S mutans strain 6715 dextransucrase also showed both the insertion and stepwise mechanisms for dextran synthesis. Sucrose was the sole glucose donor, whereas dextran was a specific, highly efficient glucose acceptor. The complex primer kinetics are not fully understood at this time and require further investigation. Without linkage analysis of the products of our enzymes, we can only postulate that each enzyme has a different function in the synthesis of interresidue and interchain alpha1-3 and alpha1-6 bonds. Insoluble dextran synthesis may involve a special enzyme mechanism characteristic of S mutans. This synthesis would require both enzymes, possibly in some aggregated form, with one enzyme synthesizing endogenous primer dextran. This endogeneous primer or some cell wall polysaccharide could stimulate both enzymes to rapidly synthesize heterogeneously linked insoluble dextran.

Chemical Phenomena↗
PubMed1985

The more Streptococcus mutans, the more caries on approximal surfaces.

The relationship between the presence of Streptococcus mutans and caries on approximal tooth surfaces was studied in a group of 28 children who were 13 years old at baseline. 700 surfaces in the pre-molar and molar region were studied. Sampling of S. mutans was performed with a toothpick method at the beginning of the study and after one and two years. From bite-wing radiographs, the approximal surfaces were recorded as caries-free, decayed, or restored. Progression of lesions during the two years was also studied. More new caries lesions and progression caries lesions were found on surfaces positive for S. mutans than on surfaces without, and the more S. mutans, the more lesions, 52% of the surfaces with positive S. mutans findings at all three sampling occasions became carious or had caries in a progressive form. Among the surfaces with no detectable S. mutans, the corresponding figure was 8%. 80 out of the 530 surfaces diagnosed as intact at the start of the study became carious over the two-year period. 69 of these were S. mutans-positive at the first and/or second sampling.

Adolescent↗
PubMed1987

Recolonization of human tooth surfaces by Streptococcus mutans after suppression by chlorhexidine treatment.

In eight subjects who were initially highly colonized with Streptococcus mutans and who used a 1% chlorhexidine gel, the numbers of this organism were suppressed in both plaque and saliva. Bacterial plaque samples were obtained from all tooth surfaces, and the recolonization pattern of S. mutans was studied over a 26-week period. At baseline, 83% of all surfaces harbored S. mutans with buccal surfaces colonized in higher frequency than the others. After chlorhexidine treatment, the proportion of tooth surfaces colonized by S. mutans was reduced to a low level. Re-appearance was slow. S. mutans was first recovered from the most posterior teeth in the mouth, the molar surfaces were recolonized earlier than were those of pre-molars and anterior teeth, and the buccal surfaces were recolonized more readily than were the other tooth surfaces. The data show that there is a specific recolonization pattern of S. mutans after chlorhexidine treatment, and that the re-emergence of S. mutans is most probably due to regrowth of bacteria which have not been eradicated.

Adult↗
PubMed1992

pH regulation by Streptococcus mutans.

The intracellular pH (pHi) optimum for glycolysis in Streptococcus mutans Ingbritt was determined to be 7.0 by use of the ionophore gramicidin for manipulation of pHi. Glycolytic activity decreased to zero as the pHi was lowered from 7.0 to 5.0. In contrast, glycolysis had an extracellular pH (pHo) optimum of 6.0 with a much broader profile. The relative insensitivity of glycolysis to the lowering of pHo was attributed to the ability of S. mutans to maintain a transmembrane pH gradient (delta pH, inside more alkaline) at low pHo. At a pHo of 5.0, glycolyzing cells of S. mutans maintained a delta pH of 1.37 +/- 0.09 units. The maintenance of this delta pH was dependent on the concentration of potassium ions in the extracellular medium. Potassium was rapidly taken up by glycolyzing cells of S. mutans at a rate of 70 nmol/mg dry weight/min. This uptake was dependent on the presence of both ATP and a proton motive-force (delta p). The addition of N-N'-dicyclohexylcarbodiimide (DCCD) to glycolyzing cells of S. mutans caused a partial collapse of the delta pH. Growth of S. mutants at pHo 5.5 in continuous culture resulted in the maintenance of a delta pH larger than that produced by cells grown at pH 7.0. These results suggest the presence of a proton-translocating F1Fo-ATPase in S. mutans whose activity is regulated by the intracellular pH and transmembrane electrical potential (delta psi). The production of an artificial delta p of 124 mV across the cell membrane of S. mutans did not result in proton movement through the F1Fo-ATPase coupled to ATP synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Acids↗