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PubMed1995

Inhibition of acid production in Streptococcus mutans R9: inhibition constants and reversibility.

End-product inhibition of acid production in Streptococcus mutans R9 was investigated by measuring effects of varying concentrations of H+ and of undissociated lactic or acetic acids on acid production rates in the pH stat. H+ caused purely uncompetitive inhibition (inhibition constant Kiu 0.018 mmol 1(-1). Lactic acid caused mixed inhibition with inhibition constants of Kiu 4.24 mmol 1(-1) and Kic 4.55 mmol 1(-1). Reversibility of inhibition by H+ showed only a statistically significant reduction only at pH < 4.5. Reversibility of inhibition by lactic and acetic acids decreased with increasing inhibitor concentration. In all cases, reversibility correlated with the extent to which viability was retained, suggesting that loss of reversibility was due to cell death. These results suggest that, after a low-pH episode in dental plaque, caused by fermentation of dietary carbohydrate, the ability of plaque organisms to produce acid in subsequent exposures to carbohydrate may be reduced.

Acetates↗

PubMed1996

Identification of a repeated epitope recognized by human serum antibodies in a surface protein antigen of Streptococcus mutans.

This study determined the antigen determinants of a 190-kDa protein antigen of Streptococcus mutans that is involved in the initial attachment to the tooth surface. In 5 subjects, the reactivities of serum antibodies to 7 overlapping surface protein antigen fragments covering the entire antigen molecule and 19 sequential overlapping synthetic 19-mer peptides covering the entire A-region of the surface protein antigen were examined with enzyme-linked immunosorbent assay (ELISA). The study showed that the A-region of the antigen is strongly immunogenic in humans and contains several widely distributed epitopes. In addition, an amino acid sequence of the one of dominant epitopes in a certain subject was identified as LTAENTAI with ELISA inhibition assays using the relevant truncated peptides. This epitope was located both at the positions from L-346 to I-364 and L-430 to E-437 of the antigen molecule, and serum antibodies against the epitope were found in 3 of the 5 subjects.

Adult↗

PubMed1995

An antigenic peptide inducing cross-reacting antibodies inhibiting the interaction of Streptococcus mutans PAc with human salivary components.

A 190-kDa surface protein antigen (PAc) of Streptococcus mutans, in particular the A region of this molecule, may be implicated in the induction of dental caries via an interaction with salivary components. For this reason, it was probably used successfully as an antigenic component for experimental vaccination to prevent dental caries in animals. While developing a synthetic peptide vaccine for dental caries, as reported herein, we have identified a unique peptide, TYEAALKQYEADL, as a candidate vaccinal immunogen. The amino acid sequence of this peptide completely corresponds to the sequence of a B-cell epitope in the A region of PAc and additionally contains its own T-cell epitope for B10.D2 mice within the molecule. This peptide strongly induces the production of only cross-reacting antibodies against PAc. In addition, as demonstrated by surface plasmon resonance analysis using the BIAcore system, these cross-reacting antibodies inhibit approximately 50% of the binding of fluid-phase salivary components to immobilized recombinant PAc.

Adult↗

PubMed1983

[Genetic control of the immune response to Streptococcus mutans, insulins and (T,G)-A--L in the rat].

The immune response to Streptococcus mutans antigen, (T,G)-A--L, bovine insulin (B.I.) and pork insulin (P.I.) in the rat was studied by the double antibody method and/or the in vitro antigen-induced lymphocyte proliferation assay. Results were revealed that over ten inbred strains of rats were divided into high and low responders against the each antigen. Two high responders to insulins, SDJ (RT1U) and BN (RT1n) strains of rats were appeared to recognize different antigenic determinant (s) on the insulin molecule. The results of linkage and segregation analyses in F1, F2, backcross and partially congenic progenies were as follows: The immune response genes, Ir-(T,G)-A--L and Ir-B.I., which controlled the high responsiveness against (T,G)-A--L and B.I., respectively, and the immune suppression gene, Is-B.I., which controlled the low responsiveness to B.I. could be assumed. Ir(T,G)-A--L, Ir-B.I. and Is-B.I. were closely linked to RT1, which is the major histocompatibility complex of the rat.

Animals↗

PubMed1997

Antigenicity of a synthetic peptide from glucosyltransferases of Streptococcus mutans in humans.

Human salivary immunoglobulin A (IgA) and serum IgG antibodies to the Streptococcus mutans glucosyltransferases (Gtfs) and to a synthetic peptide of 19 amino acids from a conserved region in the Gtfs (residues 435 to 453) were determined in young adults by enzyme-linked immunosorbent assay. Varying levels of antibody to Gtfs were detected in saliva or serum, with significantly higher levels of antibody to GtfD than to GtfB/C or GtfC. Anti-Gtf IgA levels in saliva did not correlate with those of IgG in serum. Caries-free (CF) volunteers exhibited significantly higher salivary IgA antibody levels to the peptide and to GtfB/C or GtfC than did the caries-active (CA) subjects. Preincubation of CF saliva and serum with the peptide inhibited the antibodies to the Gtfs in a dose-dependent manner, whereas preincubation of the samples from the CA group resulted in only partial inhibition. Our results indicated that this 19-amino-acid peptide includes one of the major B-cell epitopes of Gtfs and that CF individuals have higher titers of antibodies than CA subjects.

Adolescent↗

PubMed2005

Regulation of bacteriocin production in Streptococcus mutans by the quorum-sensing system required for development of genetic competence.

In Streptococcus mutans, competence for genetic transformation and biofilm formation are dependent on the two-component signal transduction system ComDE together with the inducer peptide pheromone competence-stimulating peptide (CSP) (encoded by comC). Here, it is shown that the same system is also required for expression of the nlmAB genes, which encode a two-peptide nonlantibiotic bacteriocin. Expression from a transcriptional nlmAB'-lacZ fusion was highest at high cell density and was increased up to 60-fold following addition of CSP, but it was abolished when the comDE genes were interrupted. Two more genes, encoding another putative bacteriocin and a putative bacteriocin immunity protein, were also regulated by this system. The regions upstream of these genes and of two further putative bacteriocin-encoding genes and a gene encoding a putative bacteriocin immunity protein contained a conserved 9-bp repeat element just upstream of the transcription start, which suggests that expression of these genes is also dependent on the ComCDE regulatory system. Mutations in the repeat element of the nlmAB promoter region led to a decrease in CSP-dependent expression of nlmAB'-lacZ. In agreement with these results, a comDE mutant and mutants unable to synthesize or export CSP did not produce bacteriocins. It is speculated that, at high cell density, bacteriocin production is induced to liberate DNA from competing streptococci.

Amino Acid Sequence↗

PubMed1981

Extracellular polysaccharide synthesized by the oral bacterium Streptococcus mutans of serotype a to e in vitro.

Extracellular polysaccharide (EPS) synthesized in vitro by Streptococcus mutans belonging to serotypes a, b, c, d and e was shown to consist mainly of glucan. Only strains of type b and e regularly produced substantial amounts of fructan, too. Strains of type d synthesized significantly higher quantities of glucan than strains of the other types per gram of bacterial mass. The percentage of insoluble glucan was lowest in samples from strains of type a and c, and highest in samples from strains of type d. In contrast to the insoluble glucan, the linkage pattern of the soluble glucan of the five types showed only small differences. The percentage of alpha-1,3-linked glucose units was highest in the insoluble glucan from strains of type d and e, and lowest in glucan from type c. The differences were significant. Incubation of Strep. mutans under various culture conditions showed that the quantities and composition of EPS formed depend on the culture condition used. The effect of culture conditions, however, was similar for all strains. Therefore the differences found with respect to the quantities and composition of EPS synthesized in vitro by Strep. mutans of different types are apparently type-dependent.

Culture Media↗

PubMed1985

Expression of a gene for glucan-binding protein from Streptococcus mutans in Escherichia coli.

The structural gene for a glucan-binding protein (GBP) of Streptococcus mutans has been inserted into a bacteriophage lambda vector and expressed in Escherichia coli K12. Lysates of E. coli infected with the recombinant phage contain an antigenic protein of the same size as S. mutans GBP. The GBP synthesized in E. coli can be affinity-purified on immobilized glucan and antiserum raised against it has been shown to precipitate fructosyltransferase activity from S. mutans.

Antigens, Bacterial↗

PubMed1988

Effects of panose on glucan synthesis and cellular adherence by Streptococcus mutans.

The effects of panose on glucan synthesis and sucrose-dependent cellular adherence by Streptococcus mutans were investigated. Panose effectively inhibited glucan synthesis from sucrose by glucosyltransferases from S. mutans strain 6715, but increasing amounts of panose increased the release of fructose from sucrose by the enzymes. On the other hand, production of a series of oligosaccharides of increasing size by the enzymes was markedly enhanced in the presence of panose. These results indicate that panose activates the enzymes and that the inhibition of glucan synthesis by panose is due to the transfer of the glucosyl group of sucrose to panose. Sucrose-dependent adherence of cells of various S. mutans strains to a glass surface was also inhibited by panose.

Bacterial Adhesion↗

PubMed1978

Binding of glucosyltransferase and glucan synthesis by Streptococcus mutans and other bacteria.

Lyophilized and heat-treated cells from the seven serotypes of Streptococcus mutans were examined for their ability to bind added insoluble-product glucosyl-transferase (GTase) and to synthesize cell-associated glucan from [(14)C]sucrose. Lyophilized cells of serotypes a and g did not synthesize any more additional glucan than did the controls after exposure to GTase. These cells, however, synthesized four- to eightfold-greater quantities of glucan than did the cells of the remaining serotypes. Lyophilized cells of serotypes b, c, d, e, and f synthesized two- to threefold-greater quantities of glucan after exposure to GTase than did the controls without added enzyme. Lyophilized cells of serotypes a and g synthesized 6- to 10-fold-greater quantities of glucan than did heat-treated cells of the same strain after binding of GTase. Lyophilized cells of the remaining serotypes synthesized only 1.6- to 3.3-fold-greater quantities of glucan than did the heat-treated cells. These results demonstrate that heat treatment to inactivate cell-associated GTase does not create additional GTase binding sites in S. mutans and that serotypes a and g are considerably more active in cell-associated glucan synthesis than cells of the other five serotypes. Ten species of gram-positive and gram-negative bacteria from five genera which do not produce in vitro plaque synthesized 10- to 100-fold-less glucan than did the S. mutans strains after exposure to GTase. Of these species, S. sanguis, Actinomyces viscosus, and A. naeslundii synthesized the largest quantities of glucan. Three mutant strains of S. mutans which possess a reduced ability for in vitro adherence but do agglutinate with glucan or dextran synthesized only one-third as much glucan after binding of GTase as the control. These results are discussed in relation to in vitro and in vivo plaque development and the agglutination of S. mutans. The results support earlier findings which indicate that the presence of bacterial species other than S. mutans in smooth-surface dental plaque is due in part to contact of the cells with glucan in the developing plaque and not to the binding of cell-free GTase and the in situ synthesis of glucan. The results obtained with these representative strains of the seven serotypes of S. mutans may not apply to the same extent to other strains within the serotypes.

Escherichia coli↗

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↗

PubMed2000

Salivary Streptococcus mutans, Lactobacilli levels and buffer capacity in children with esophageal burns.

Children with esophageal burns due to toxic ingestion are medically compromised in many ways. They have problems like strictures in esophagus, dysphagia, gastroesophageal reflux and necessity to be fed with a special soft diet. Taking these distinctive features into consideration, we aimed to study these children with special focus on the dental caries risk. The experimental group consisted of 33 children between 2 and 14 years old (mean age 6.42 +/- 0.56) who had received stricture treatment in the Pediatric Surgery Department of our university. The control group consisted of 20 healthy children aged between 3 and 14 (mean age 7.25 +/- 0.7) who applied to the Pedodontics department for dental treatment. While mean dfs (+/- SE) was 11.13 +/- 2.30 and mean DMFs (+/- SE) was 9.79 +/- 4.76 in the experimental group, mean dfs (+/- SE) was found as 11.53 +/- 2.16 and mean DMFS (+/- SE) was 1.90 +/- 0.56 in control group. For the determination of Streptococcus mutans (SM), Lactobacilli (LB) and Buffer capacity (BC), salivary tests of Dentocult SM (Vivacult SM Vivadent-Liechtenstein), Dentocult LB (Vivacult LB-Vivadent-Liechtenstein) and Dentobuff (Vivacult BC-Vivadent-Liechtenstein) were applied to both groups. Our findings were evaluated statistically and compared by the Mann Whitney Confidence Test. The amount of Streptococcus mutans, Lactobacilli and the level of buffering capacity in the children with esophageal burns showed a high caries risk. Positive correlations were found between SM and LB, SM and dfs, LB and dfs levels and DMFs and duration of stricture treatment (p < 0.05). However, negative correlations were found between BC and DMFs, DMFs and tooth brushing habit, dental visit and DMFs (p < 0.05). The mean DMFs, LB and SM levels were lower and BC levels were higher in the control group. Although a significant difference was found between DMFs scores (p < 0.05), no significant difference was found between LB, BC, SM and dfs levels (p > 0.05). It could be concluded that children with esophageal burns have high dental caries risk and for this reason parental counseling about oral hygiene, diet, dental plaque controlling and preventive dental regimens have an importance in these medically compromised children.

Adolescent↗

PubMed1987

Analysis of heart-reactive antibodies induced in rabbits by immunization with Streptococcus mutans.

The induction of antibodies that react with human heart muscle in rabbits immunized with Streptococcus mutans and related organisms has been investigated in order to re-examine the reported antigenic cross-reactivity between the major cell wall protein antigen I/II of S. mutans and heart tissue. Serum from 2 of 8 rabbits hyperimmunized with whole cells of S. mutans, S. sobrinus, S. rattus, or S. mitis, assayed by immunofluorescence and radioimmunoassay, revealed antibodies reactive with sarcolemma that could be attributed to immunization. Antisera raised against several crude and purified antigens of S. mutans did not reveal heart-reactive antibodies, that could be attributed to antigenic similarity between heart and these antigens. An assay designed to detect antibodies that could simultaneously bind to both heart and antigen I/II of S. mutans failed to reveal cross-reactivity due to this antigen, although antibodies separately expressing these binding activities were demonstrable. IgM rheumatoid factor was elevated in several antisera to S. mutans, and could have contributed to some previous observations ascribed to antigenic cross-reactivity between S. mutans and human heart muscle.

Animals↗

PubMed2001

Passive transfer of immunoglobulin Y antibody to Streptococcus mutans glucan binding protein B can confer protection against experimental dental caries.

Active immunization with Streptococcus mutans glucan binding protein B (GBP-B) has been shown to induce protection against experimental dental caries. This protection presumably results from continuous secretion of salivary antibody to GBP-B, which inhibits accumulation of S. mutans within the oral biofilm. The purpose of this study was to explore the influence of short-term (9- or 24-day) passive oral administration of antibody to S. mutans GBP-B on the longer-term accumulation and cariogenicity of S. mutans in a rat model of dental caries. Preimmune chicken egg yolk immunoglobulin Y (IgY) or IgY antibody to S. mutans GBP-B was supplied in lower (experiment 1) and higher (experiment 2) concentrations in the diet and drinking water of rats for 9 (experiment 1) or 24 (experiment 2) days. During the first 3 days of IgY feeding, all animals were challenged with 5 x 10(6) streptomycin-resistant S. mutans strain SJ-r organisms. Rats remained infected with S. mutans for 78 days, during which rat molars were sampled for the accumulation of S. mutans SJ-r bacteria and total streptococci. Geometric mean levels of S. mutans SJ-r accumulation on molar surfaces were significantly lower in antibody-treated rats on days 16 and 78 of experiment 2 and were lower on all but the initial (day 5) swabbing occasions in both experiments. Relative to controls, the extent of molar dental caries measured on day 78 was also significantly decreased. The decrease in molar caries correlated with the amount and duration of antibody administration. This is the first demonstration that passive antibody to S. mutans GBP-B can have a protective effect against cariogenic S. mutans infection and disease. Furthermore, this decrease in infection and disease did not require continuous antibody administration for the duration of the infection period. This study also indicates that antibody to components putatively involved only in cellular aggregation can have a significant effect on the incorporation of mutans streptococci in dental biofilm.

Animals↗

PubMed2006

The Streptococcus mutans vicX gene product modulates gtfB/C expression, biofilm formation, genetic competence, and oxidative stress tolerance.

Streptococcus mutans is considered one of the primary etiologic agents of dental caries. Previously, we characterized the VicRK two-component signal transduction system, which regulates multiple virulence factors of S. mutans. In this study, we focused on the vicX gene of the vicRKX tricistronic operon. To characterize vicX, we constructed a nonpolar deletion mutation in the vicX coding region in S. mutans UA159. The growth kinetics of the mutant (designated SmuvicX) showed that the doubling time was longer and that there was considerable sensitivity to paraquat-induced oxidative stress. Supplementing a culture of the wild-type UA159 strain with paraquat significantly increased the expression of vicX (P < 0.05, as determined by analysis of variance [ANOVA]), confirming the role of this gene in oxidative stress tolerance in S. mutans. Examination of mutant biofilms revealed architecturally altered cell clusters that were seemingly denser than the wild-type cell clusters. Interestingly, vicX-deficient cells grown in a glucose-supplemented medium exhibited significantly increased glucosyltransferase B/C (gtfB/C) expression compared with the expression in the wild type (P < 0.05, as determined by ANOVA). Moreover, a sucrose-dependent adhesion assay performed using an S. mutans GS5-derived vicX null mutant demonstrated that the adhesiveness of this mutant was enhanced compared with that of the parent strain and isogenic mutants of the parent strain lacking gtfB and/or gtfC. Also, disruption of vicX reduced the genetic transformability of the mutant approximately 10-fold compared with that of the parent strain (P < 0.05, as determined by ANOVA). Collectively, these findings provide insight into important phenotypes controlled by the vicX gene product that can impact S. mutans pathogenicity.

Bacterial Adhesion↗

PubMed1982

Effects of exogenous soluble dextrans on insoluble glucan synthesis by Streptococcus mutans glucosyltransferase.

Production of water-insoluble glucan (ISG) from sucrose by cell-free Streptococcus mutans AHT glucosyltransferase (GTF) first rapidly increased, and then sharply declined, as the amounts of water-soluble Dextrans T20 approximately T500 present, were increased. The decline of ISG synthesis was accompanied by an increased synthesis of the water-soluble fraction (SG). Prolonged incubation, however, induced enhanced synthesis of ISG even at higher dextran concentrations. The concentration of dextran required to stimulate or suppress ISG synthesis depended on the amounts of GTF used, but the extent of the stimulation was almost identical for the same GTF/dextran ratio. Thus, ISG synthesis is stimulated by the presence of dextrans at relatively low concentrations, but retarded at higher concentrations by being shifted to SG synthesis. ISG produced in the presence of dextrans contained higher proportions of alpha-1,6 glucosidic linkage and lower molecular size fractions, and possessed lower viscosity. These ISG products did not exhibit the coalescence of two component fibrils as observed with control ISG. These changes combined may contribute to the reduction of ISG-dependent adherence to glass of S. mutans cells by the presence of soluble dextrans, irrespective of their molecular size and concentration.

Adhesiveness↗

PubMed1995

Salivary count of Streptococcus mutans in elementary school children.

Previous studies have documented that persons with high levels of Streptococcus mutans are "at risk" for dental caries. The objective of this study was to identify children at an early age who were "at risk" for caries. The sample consisted of 77 school children aged 9-13 years old. The majority of the sample was African-Americans (55.8%). Approximately 51% were females. The Dentocult SM Strip Mutans Test was used to estimate the S. mutans count in saliva. The method is based on the use of a selected culture broth and the adhere S. mutans count of < 1,000,000 bacteria ml saliva and children with S. mutans count of < 1,000,000 were classified as "low risk" for caries. The DMF-T was used to estimate the number of decayed, missing and filled teeth. The decayed mean score = 1.85; range = 0-9. Only two children had teeth missing (one in each). The number of filled teeth was low; mean = .88; range = 0-6. The DMF-T mean score was 2.75; range = 0-9. Correlations were sought between levels of S. mutans rates and decayed teeth. Low, but nonsignificant, correlations were found between S. mutans and decayed teeth (r = .20). This trend continued for S. mutans levels and the DMF-T (r = .16). Analysis of Variance Test (ANOVA) indicated a significant effect by sex on the levels of S. mutans P < .05 (females had higher S. mutans levels than males). There was no significant difference or interaction noted in DMF-T scores by sex or race. In addition no significant difference was noted in the number of decayed teeth by sex or race. Our results indicate that females in this age group are potentially at greater risk for dental caries than their male counterparts due to the observed higher levels of S. mutans. This observation deserves further study.

Adolescent↗

PubMed2005

Frequency of four different mutacin genes in Streptococcus mutans genotypes isolated from caries-free and caries-active individuals.

The ability of Streptococcus mutans to produce mutacins, combined with the production of other virulence factors such as lactic acid, may contribute to the pathogenesis of this bacterium. In the present study, the detection of genes encoding mutacin types I/III, II and IV was performed by PCR with specific primers to each type in a total of 63 S. mutans genotypes isolated from caries-active and caries-free individuals. In the caries-free group, PCR screening for mutacin IV revealed that 31.8% of strains were positive for this mutacin. PCR for the other three mutacins tested (I/III and II) did not yield amplicons in any S. mutans strains in this group. The PCR with primers of mutacin IV showed 68.3% positive genotypes in the caries-active group, on the other hand, the amplicons of mutacins I/III revealed 41.5% positive strains that carried these genes. The chi square test showed significant differences in the number of positive strains to mutacin IV when comparing the caries-free and caries-active genotypes of S. mutans (P = 0.01). All tested S. mutans strains were negative by PCR for mutacin II. The low frequencies of detection of some mutacin genes suggest the existence of high diversity and polymorphism in the production of genetic determinants of mutacin-like substances. In addition, the production of a wide spectrum of mutacins can play an important biological role in colonization by S. mutans strains, mainly in the niche of high-complexity microbial communities.

Adolescent↗