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PubMed1989

Pulp response to, and cariogenicity of, a strain of Streptococcus mutans.

Gnotobiotic rats mono-infected with Streptococcus mutans (NCTC 10919) were maintained on a high sucrose diet in an isolator. When they were 8 weeks old the pulps of their maxillary first and second molars were mechanically exposed and left open to the oral environment. The rats were sacrificed in groups after 7 and 28 days. Thirty-seven teeth were available for study in the 7-day group, and 30 teeth in the 28-day group. The test S. mutans was non-cariogenic. After 7 days, necrosis of the superficial layers of the pulp was noted; however, after 28 days pulpal necrosis was much more extensive and calcific repair was observed in only one-third of the teeth examined. The microorganism did not provoke inflammation in the pulp or periapical tissues. This is the second strain of S. mutans tested in this manner. These results are very similar to those reported previously for S. mutans (NCTC 10449) and strengthens the view that organisms of the S. mutans group have a low pathogenicity for the pulp.

Animals↗
PubMed2004

Non-disruptive, real-time analyses of the metabolic status and viability of Streptococcus mutans cells in response to antimicrobial treatments.

Streptococcus mutans is one of a small number of recognized pathogens that lives among the hundreds of other bacterial species which comprise the oral flora. The virulence of this organism is intimately associated with its ability to live as an attached biofilm community on the tooth surface, and consequently, there is a great interest in its biofilm lifestyle. Currently, there are no established protocols that facilitate drug screening against this organism while it is entrenched in the biofilm. Furthermore, greater complications arise when attempting to perform these experiments in a multi-species setting. In an effort to circumvent these problems, we developed a quick, real-time, and non-disruptive method to probe the metabolic status of S. mutans growing as either a planktonic culture or a biofilm community. This assay takes advantage of the proven utility of luciferase measurements for drug screening. We placed the luciferase gene under the control of the S. mutans lactate dehydrogenase promoter (ldh) and integrated the construct onto its native position on the chromosome. We found this construct to be both highly expressed (<10000 cells easily detectable) and insensitive to many different growth parameters. When testing this reporter in both planktonic and biofilm cultures receiving either bacteriostatic or bactericidal antibiotics, we found the ldh-luc reporter to be a very accurate measurement of cell viability. Furthermore, we also demonstrated that this assay can generate useful information about the characteristics of intoxication caused by antibiotic activity. In addition, we modified the biofilm assay into the 96-well format and demonstrated the feasibility of high throughput drug screening of biofilm embedded S. mutans.

Anti-Bacterial Agents↗
PubMedDate not supplied

Carbohydrate uptake in the oral pathogen Streptococcus mutans: mechanisms and regulation by protein phosphorylation.

Streptococcus mutans is the primary etiological agent of dental caries in man and other animals. This organism and other related oral streptococci use carbohydrates almost exclusively as carbon and energy sources, fermenting them primarily to lactic acid which initiates erosion of tooth surfaces. Investigations over the past decade have shown that the major uptake mechanism for most carbohydrates in S. mutans is the phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS), although non-PTS systems have also been identified for glucose and sucrose. Regulation of sugar uptake occurs by induction/repression and inducer exclusion mechanisms in S. mutans, but apparently not by inducer expulsion as is found in some other streptococci. In addition, ATP-dependent protein kinases have also been identified in S. mutans and other oral streptococci, and a regulatory function for at least one of these has been postulated. Among a number of proteins that are phosphorylated by these enzymes, the predominant soluble protein substrate is the general phospho-carrier protein of the PTS, HPr, as had previously been observed in a variety of Gram-positive bacteria. Recent results have provided evidence for a role for ATP-dependent phosphorylation of HPr in the coordination of sugar uptake and its catabolism in S. mutans. In this review, these results are summarized, and directions for future research in this area are discussed.

Carbohydrates↗
PubMed1987

Adherence of Streptococcus mutans to implant materials.

The adherence of Streptococcus mutans OMZ-176 to six implant materials (poly-crystal alumina, single-crystal alumina, titanium alloy, cobalt-chromium-molybdenum alloy, hydroxyapatite, and heat-curing polymethylmethacrylate resin) was studied in vitro. The change of free energy, which corresponds to the adherence process, was also evaluated for hydrophobic interaction. Adherence of S. mutans to poly-crystal alumina was lower than adherence to other materials. The adherence of S. mutans to the test materials was highly correlated with the change of free energy, which suggests that hydrophobic interaction plays an important role in the adherence of S. mutans to the implant materials.

Alloys↗
PubMed2002

A DNA vaccine encoding a cell-surface protein antigen of Streptococcus mutans protects gnotobiotic rats from caries.

A cell-surface protein antigen (PAc) of Streptococcus mutans is considered a virulence factor because it may mediate initial attachment of Streptococcus mutans to tooth surfaces. Thus, inhibiting PAc is predicted to provide protection against caries. To develop vaccines against dental caries, we constructed a DNA vaccine, pCIA-P, which encodes two high-conservative regions of PAc. Expression of the recombinant protein was obtained in eukaryotic cells in vitro and in vivo. In this report, we provide evidence that fewer caries lesions, and high levels of PAc-specific salivary IgA antibody and serum IgG antibody, were observed in gnotobiotic rats following targeted salivary gland (TSG) administration of pCIA-P. This study shows that the recombinant DNA vaccine pCIA-P could induce protective anti-caries immune responses and that TSG immunization is a promising strategy for the inhibition of dental caries.

Analysis of Variance↗
PubMed1998

Adherence of Streptococcus mutans to orthodontic brackets.

The affinity of Streptococcus mutans to orthodontic brackets made from metal, plastic, and ceramic was tested. Twelve saliva-coated brackets and 12 noncoated brackets of each type were immersed in a S. mutans solution labeled with [3H] thymidine. Each sample was then immersed in distilled water at 20 degrees C for 24, 48, and 72 hours to measure the adherence of S. mutans to these samples. During the first 24 hours, the adherence of S. mutans decreased with and without saliva coating. Between 24 and 72 hours, the adherence of S. mutans to the saliva-coated brackets remained unchanged; the adherence to uncoated brackets showed a decrease. Saliva coating caused a decreased affinity of S. mutans for all products tested. The initial affinity of S. mutans to metal brackets was statistically significantly lower than that to plastic and porcelain brackets with and without saliva coating.

Adult↗
PubMed1988

Homology of glucosyltransferase gene and protein sequences from Streptococcus sobrinus and Streptococcus mutans.

The sequences of glucosyltransferase genes from Streptococcus sobrinus (gtfI) and Streptococcus mutans (gftB) were compared and show a high degree of homology. There is a 57.7% homology of nucleotides in the genes and a 56.7% homology of amino acids in the deduced protein sequences. The G + C content for the protein-coding region is 43.6% for S. sobrinus and 41.2% for S. mutans. Internal repeating sequences present in both proteins exhibit some difference in sequence pattern.

Amino Acid Sequence↗
PubMed2006

Immune response in humans to a nasal boost with Streptococcus mutans antigens.

We previously reported that a Streptococcus mutans enriched-glucosytransferase (E-GTF) preparation induces an immune response following intranasal, but not tonsillar, immunization of humans. In this study, we determined whether intranasal immunization of these subjects 2 years later resulted in augmented immune responses compared to those seen in control subjects. Subjects previously immunized via the intranasal (IN, n = 7) or tonsillar (IT, n = 7) route and control (n = 12) subjects were immunized via the intranasal route with E-GTF. Nasal wash, saliva, and serum were collected before immunization and then weekly for 3 months after immunization. Significant (P < 0.05) mucosal and serum immunoglobulin A (IgA) anti-E-GTF responses were observed in all three groups. Nasal and serum IgA anti-E-GTF responses were significantly higher (P < 0.05) in the IN group. The salivary responses in the three groups were, in general, similar. These results indicate that intranasal immunization primes the immune system for a localized secondary response to S. mutans antigens.

Administration, Intranasal↗
PubMed1990

[Effects of oxygen on growth of Streptococcus mutans].

Effects of oxygen on growth of Streptococcus mutans Ingbritt (serotype c) were examined. The strain could be passaged under aerobic conditions at 37 degrees C in a peptone/yeast extract medium containing 0.2% glucose. Although the growth rate was slightly retarded under aerobic conditions (the doubling time, 60 min; 45 min under anaerobic conditions), the increment of cellular dry weight change was 35 g per mole of glucose under both conditions. To investigate such aerotolerance in growth as indicated by these results, oxygen metabolism was compared between aerobically and anaerobically grown cells. No difference was observed in the apparent rate of superoxide production or superoxide dismutation. However, aerobically grown cells showed a higher activity of hydrogen peroxide reduction with glucose as substrate and accumulated a lower level of hydrogen peroxide when incubated with glucose under aerobic conditions. In addition, hydrogen peroxide added to the medium was less inhibitory to anaerobic growth when aerobic cells were used as the inoculum. These results indicate that aerotolerance of S. mutans Ingbritt can be ascribed at least in part to its hydrogen peroxide reducing activity which is elevated under aerobic conditions.

Hydrogen Peroxide↗
PubMed2004

Transcriptional analysis of mutacin I (mutA) gene expression in planktonic and biofilm cells of Streptococcus mutans using fluorescent protein and glucuronidase reporters.

Streptococcus mutans is implicated as the primary pathogen involved in the development of dental caries. The production of specific bacteriocins (called mutacins) by S. mutans is one of the major virulence factors which facilitate the dominance of the bacterium within dental plaque. While much has been revealed about the biochemical structures of mutacins, little is known about the expression and regulation of mutacin genes, largely due to the lack of proper methods to monitor mutacin gene expression, especially under biofilm conditions. In this study, a set of reporter systems with the green fluorescent protein (gfp), the monomeric red fluorescent protein (mrfp1), and the glucuronidase (gusA) are introduced to S. mutans to study the transcriptional activities of the mutacin I gene (mutA). Although the mutA-reporter fusions are in single copy on the chromosome, these reporter systems display strong signals that allow us to effectively monitor mutA gene expression in S. mutans. Using these reporter systems, we show that mutA is expressed in both planktonic and biofilm cells, even though mutacin activities are normally detected only in biofilm cells. Furthermore, we confirm that mutR, the gene upstream of the mutacin operon, is required for mutacin I gene expression. The success of this study validates the feasibility of using these reporter systems to study gene expression and regulation in S. mutans.

Artificial Gene Fusion↗
PubMed1998

Rapid and quantitative detection of Streptococcus mutans with species-specific monoclonal antibodies.

Streptococcus mutans is known to be a prime etiologic agent for the initiation and progression of human dental caries. Rapid, accurate, and quantitative detection of S. mutans will help us better understand the pathogenic mechanisms of dental caries and will help to develop methods for caries diagnosis and risk assessment. This study describes the development of three highly species-specific monoclonal IgG antibodies against S. mutans. The antibodies were used to develop a number of methods that quantitatively detect S. mutans in less <1 min and are sensitive enough to detect a single bacterial cell. These methods could be widely used in basic and clinical studies related to S. mutans and in the clinical diagnosis and treatment of caries in humans.

Antibodies, Bacterial↗
PubMed1993

Collagen mediates adhesion of Streptococcus mutans to human dentin.

Some strains of Streptococcus mutans were found to recognize and bind collagen type I. Binding of 125I-labeled collagen type I was specific in that collagen types I and II, but not unrelated proteins, were able to inhibit binding of the labeled ligand to bacteria. Collagen binding to S. mutans was partially reversible and involved a limited number of bacterial binding sites per cell. S. mutans UA 140 cells bound collagen type I with high affinity (Kd = 8 x 10(-8) M). The number of binding sites per cell was 4 x 10(4). Collagen-binding strains of S. mutans were found to adhere to collagen-coated surfaces as well as to pulverized root tissue. S. mutans strains that did not bind the soluble ligand were unable to adhere to these substrata. Adherence to collagen-coated surfaces could be inhibited with collagen or clostridial collagenase-derived collagen peptides. Adherence of S. mutans to dentin was enhanced by collagen types I and II but inhibited by collagen peptides. S. mutans UA 140 bound significantly less 125I-collagen type I following treatment with peptidoglycan-degrading enzymes. These enzymes released a collagen-binding protein (collagen receptor) with a relative molecular size of 16 kDa. The results of this study suggest that collagen mediates adhesion of S. mutans to dentin. This interaction may target collagen-binding strains of S. mutans to dentin in the oral cavity and may play a role in the pathogenesis of root surface caries.

Adhesins, Bacterial↗
PubMed1976

Formation of cross-reacting antibodies against cellular and extracellular lipoteichoic acid of Streptococcus mutans BHT.

Antisera prepared against strains of Streptococcus mutans, particularly strain BHT, contain antibodies to the membrane lipoteichoic acid component that will cross-react with lipoteichoic acids from three species of lactobacilli. A more detailed study of the antibodies to strain BHT confirmed that the antibodies are specific for the polyglycerol phosphate component common to the lipoteichoic acids. Sera with a higher hemagglutinating titer could be obtained by injecting disrupted organisms. The partially purified lipoteichoic acid isolated from the culture fluid of S. mutans BHT was also immunogenic antibodies; antibodies were also formed against another unidentified component in this extracellular fraction.

Antibodies↗
PubMed1983

Available immunoglobulin A antibodies in mouth rinses and implantation of Streptococcus mutans.

Immunoglobulin A (IgA) antibodies reacting with Streptococcus mutans were analyzed in mouth rinses from 38 adults. Antibody activity was determined by an enzyme-linked immunosorbent assay. The IgA antibody activity varied considerably in samples from different individuals. Of the 38 subjects, 12 volunteered in an implantation experiment and were challenged with streptomycin-resistant S. mutans. The results indicated that individuals with relatively high IgA antibody activity in mouth rinses more rapidly eliminated the challenge strain than subjects with low IgA antibody activity.

Adult↗
PubMed2000

Salivary and serum antibody response to Streptococcus mutans antigens in humans.

Humoral immunity against Streptococcus mutans infection was analyzed in caries-active and caries-free young adults by immunoblotting. All volunteers from both groups had detectable salivary immunoglobulin A (IgA) and serum IgG antibodies, with similar profiles. They could be classified on the basis of relative intensity of the immunoblot bands into categories of high or low responders. Common protein antigens with molecular weight ranging from approximately 45 to 190 kDa could be found either extracellularly or associated with the cell wall of S. mutans cultured in vitro. The predominant reactive antigens recognized by both IgA and IgG were of proteins around 63 and 60 kDa. Detection of IgA antibodies to the various antigens of S. mutans in individual saliva samples did not always correlate with serum IgG antibody profiles. In addition, distinct bands, which reacted preferentially with either IgA or IgG, could be detected by antibodies from specific subjects. Differential reactivities of salivary IgA and serum IgG antibodies to two, cell-wall associated protein antigens around 33 and 36 kDa were found in caries-active and caries-free young adults; 30.8% of caries-free subjects and 12% of caries-active subjects (P < 0.01) exhibited detectable antibody response to these antigens. This difference was not attributable to variations in antibody levels, since antibody response to these proteins were still detectable in some caries-free but not caries-active individuals whose levels of antibodies to other antigens were low. Thus, a new antibody profile which correlates with dental caries disease activity has been identified in a selected population. Differences in mucosal and systemic immune responses to S. mutans seem to be both antigen and host dependent.

Adolescent↗
PubMed2006

Streptococcus mutans: fructose transport, xylitol resistance, and virulence.

Streptococcus mutans, the primary etiological agent of human dental caries, possesses at least two fructose phosphotransferase systems (PTSs), encoded by fruI and fruCD. fruI is also responsible for xylitol transport. We hypothesized that fructose and xylitol transport systems do not affect virulence. Thus, colonization and cariogenicity of fruI(-) and fruCD(-) single and double mutants, their WT (UA159), and xylitol resistance (X(r)) of S. mutans were studied in rats fed a high-sucrose diet. A sucrose phosphorylase (gtfA(-)) mutant and a reference strain (NCTC-10449S) were additional controls. Recoveries of fruI mutant from the teeth were decreased, unlike those for the other strains. The fruCD mutation was associated with a slight loss of cariogenicity on enamel, whereas mutation of fruI was associated with a loss of cariogenicity in dentin. These results also suggest why xylitol inhibition of caries is paradoxically associated with spontaneous emergence of so-called X(r) S. mutans in habitual human xylitol users.

Animals↗
PubMed1989

Local oral immunization with synthetic peptides induces a dual mucosal IgG and salivary IgA antibody response and prevents colonization of Streptococcus mutans.

A small cell surface antigen of Streptococcus mutans was partially sequenced and the amino terminal peptides of 11, 15 and 20 amino acid residues and a dimer of the 15 and 20 residues peptides were synthesized. The synthetic peptides (SP) were used in topical oral immunization of the gingivomucosal epithelium of macaque monkeys. Sequential examination for antibodies over a period of up to 30 weeks revealed that six applications of the linear or cyclized SP11 and a random SP11 induced negligible or very low antibody levels. In contrast, the SP17 (SP15 with added cysteine at each terminus), SP21 (SP20 with one cysteine) and the dimer (SP35) induced significant anti-SP as well as anti-native streptococcal antibodies in the gingival fluid and in saliva. The functional significance of this immune response was examined by studying its effect on oral colonization of S. mutans following feeding of a carbohydrate-rich diet. Whereas control animals, sham-immunized with a random SP of 11 residues, showed increased colonization of the teeth by S. mutans, there was no colonization or a significant reduction in colonization of animals immunized with the cyclized SP17, linear SP21 or dimerized SP35. These experiments suggest that local immunization with SP derived from the sequences of a streptococcal cell surface antigen induce a dual local immune response of gingival IgG and salivary IgA antibodies against the SP and native SA. These antibodies may be involved in preventing colonization of S. mutans, which is the principal agent in the development of dental caries.

Animals↗