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PubMed2006

The effect of xylitol on Streptococcus mutans in children.

A study was performed on 91 second-grade students from the Los Angeles Unified School District to test the effects of xylitol chewing gum on Streptococcus mutans in the saliva. Saliva was collected from students and tested for the first time using the new University of California, Los Angeles, monoclonal antibody testing method. Students found to have moderate or high levels of salivary S. mutans were administered four tablets/day of xylitol gum for three weeks. The levels of S. mutans in the saliva of children in the high caries index subgroup decreased by 61.7 percent. Xylitol can be dispensed in a public school setting by school nurses and can be a very safe, efficient and inexpensive preventative measure for children at high risk for dental caries.

Antibodies, Monoclonal↗

PubMed2006

Comparative analysis of a monoclonal antibody-based Streptococcus mutans detection method with selective culture assays using polymerase chain reaction as a gold standard.

The aim of this study was to compare a recently developed monoclonal antibody (MAb)-based salivary Streptococcus mutans detection method with various selective media using polymerase chain reaction (PCR) as the gold standard. Salivary S. mutans cells were enumerated with a MAb-based method, along with three commonly used selective media, mitis-salivarius-bacitracin agar (MSB), trypticase yeast-extract cystine sucrose bacitracin agar (TYCSB), and glucose-sucrose-potassium tellurite-bacitracin (GSTB) agar. Statistical analysis showed no significant correlations between each method. With PCR as the standard, a MAb-based detection method was found to provide the highest sensitivity (91%) and specificity (96%) among these four methods. This study demonstrates that the MAb-based detection method may provide more accurate enumeration of salivary S. mutans than selective media.

Animals↗

PubMed2001

Construction and in vitro expression of Streptococcus mutans surface protein encoding DNA vaccine.

DNA vaccine plasmids were constructed that encoded two highly-conservative regions of a surface protein, PAc, from the human major cariogenic bacterium, Streptococcus mutans. Antigen expression was evaluated in vitro by immunohistochemical analysis of human endothelial cells following cationic liposome-mediated transient transfection with recombinant plasmid. The results of this study provided a basis for further testing of these recombinant plasmids in primates and for efficacy testing of dental caries DNA vaccines in human volunteers in future.

Antibodies, Bacterial↗

PubMed1979

Properties of Streptococcus mutans grown in a synthetic medium: binding of glucosyltransferase and in vitro adherence, and binding of dextran/glucan and glycoprotein and agglutination.

The influence of culture media on various properties of Streptococcus mutans was investigated. Strains of S. mutans (serotypes c, d, f, and g) were grown in a complex medium (Todd-Hewitt broth [THB]) or a synthetic medium (SYN). The SYN cells, in contrast to THB cells, did not bind extracellular glucosyltransferase and did not produce in vitro adherence. Both types of cells possessed constitutive levels of glucosyltransferase. B13 cells grown in SYN plus invertase-treated glucose possessed the same level of constitutive enzyme as THB cells. In contrast to THB cells, the SYN cells of seven serotype strains did not agglutinate upon the addition of high-molecular-weight dextran/glucan. Significant quantities of lower-molecular-weight (2 x 10(4) or 7 x 10(4)) dextran and B13 glucan were bound by SYN cells. SYN cells agglutinated weakly in anti-glucan serum (titers, 0 to 16), whereas THB cells possessed titers of 32 to 256. Evidence for the existence of a second binding site in agglutination which does not possess a glucan-like polymer has been obtained. B13 cells grown in invertase-treated THB agglutinated to the same degree as normal THB cells. The nature of this site is unknown. SYN cells possess the type-specific polysaccharide antigen. B13 cells did not bind from THB a glycoprotein which reacts with antisera to the A, B, or T blood group antigens or which allows agglutination upon the addition of dextran. The results demonstrate that S. mutans grown in a chemically defined medium possesse markedly different biochemical and biological activities than cells grown in a complex organic medium.

Agglutinins↗

PubMedDate not supplied

Physiological effects of sucrose substitutes and artificial sweeteners on growth pattern and acid production of glucose-grown Streptococcus mutans strains in vitro.

The synergistic effects of four sucrose substitutes, polysorbate and five artificial sweeteners were studied in vitro on growth pattern and acid production of seven glucose-grown Streptococcus mutans strains, representing the five serological groups after Bratthall. Four distinct growth patterns during glucose fermentation were observed: high rate of growth with low acid production, moderate growth rate with moderate acid production, moderate growth rate with high acid production, and slow rate of growth with moderate acid production. Depending on the strain used, the final OD at 546 nm ranged from 0.55 to 0.99 and the final pH of the medium varied between 4.65 and 4.15. While added sucrose substitutes, with exceptions, usually enhanced growth rate, most artificial sweeteners suppressed or, at higher concentrations, even inhibited growth of S. mutans; addition of polysorbate to the medium always increased growth rate of S. mutans significantly. The presence of sucrose substitutes during glucose fermentation had no effect on final pH of the medium, but addition of artificial sweeteners, especially sodium saccharin, elevated final pH up to 1.8 units. The observed physiological patterns and differences within the several strains of S. mutans during glucose fermentation in vitro do not necessarily relate to the five serological groups of the species.

Fructose↗

PubMed1988

Streptococcus mutans vertebral osteomyelitis.

Vertebral osteomyelitis is a disease most often encountered in the adult population, especially in the elderly. The usual etiologic agent is Staphylococcus aureus. We report a case of Streptococcus mutans endocarditis resulting in hematogenous osteomyelitis of the lumbar vertebrae.

Endocarditis, Subacute Bacterial↗

PubMed1999

Functions of two types of NADH oxidases in energy metabolism and oxidative stress of Streptococcus mutans.

We have previously identified two distinct NADH oxidases corresponding to H(2)O(2)-forming oxidase (Nox-1) and H(2)O-forming oxidase (Nox-2) induced in Streptococcus mutans. Sequence analyses indicated a strong similarity between Nox-1 and AhpF, the flavoprotein component of Salmonella typhimurium alkyl hydroperoxide reductase; an open reading frame upstream of nox-1 also showed homology to AhpC, the direct peroxide-reducing component of S. typhimurium alkyl hydroperoxide reductase. To determine their physiological functions in S. mutans, we constructed knockout mutants of Nox-1, Nox-2, and/or the AhpC homologue; we verified that Nox-2 plays an important role in energy metabolism through the regeneration of NAD(+) but Nox-1 contributes negligibly. The Nox-2 mutant exhibited greatly reduced aerobic growth on mannitol, whereas there was no significant effect of aerobiosis on the growth on mannitol of the other strains or growth on glucose of any of the strains. Although the Nox-2 mutants grew well on glucose aerobically, the end products of glucose fermentation by the Nox-2 mutant were substantially shifted to higher ratios of lactic acid to acetic acid compared with wild-type cells. The resistance to cumene hydroperoxide of Escherichia coli TA4315 (ahpCF-defective mutant) transformed with pAN119 containing both nox-1 and ahpC genes was not only restored but enhanced relative to that of E. coli K-12 (parent strain), indicating a clear function for Nox-1 as part of an alkyl hydroperoxide reductase system in vivo in combination with AhpC. Surprisingly, the Nox-1 and/or AhpC deficiency had no effect on the sensitivity of S. mutans to cumene hydroperoxide and H(2)O(2), implying that the existence of some other antioxidant system(s) independent of Nox-1 in S. mutans compensates for the deficiency.

Adaptation, Biological↗

PubMed1998

Regulation of sucrose-6-phosphate hydrolase activity in Streptococcus mutans: characterization of the scrR gene.

Previous results have implicated an important role for the enzyme IIScr, the sucrose-specific permease, in the transport of sucrose by cariogenic Streptococcus mutans. The product of the scrB gene, sucrose-6-phosphate hydrolase (Suc-6PH), is required for the metabolism of phosphorylated sucrose. The results from the utilization of scrB::lacZ fusions in S. mutans GS-5 have suggested that sucrose-grown cells have higher levels of scrB gene expression than do cells grown with glucose or fructose. Northern blot analysis of scrB transcripts has also confirmed the relative strengths of expression as sucrose>glucose>fructose. Immediately downstream from the scrB gene, an open reading frame with homology to regulatory proteins of the GalR-LacI family as well as to ScrR proteins from several other bacteria has been identified. In addition, this gene appears to be transcribed in the same operon as scrB. Inactivation of this gene, scrR, did not alter the relative expression of the scrB gene in the presence of sucrose or fructose but did increase SUC-6PH levels in the presence of glucose to that observed with sucrose. Furthermore, the S. mutans ScrR homolog appears to bind to the scrB promoter region as determined from the results of gel shift assays. These results suggest that the scrR gene is involved in the regulation of scrB, and likely scrA, expression. However, it is not clear whether sucrose acts as an inducer of expression of these genes or, alternatively, whether glucose and fructose act as repressors.

Amino Acid Sequence↗

PubMed2003

Changes in enamel surface roughness and adhesion of Streptococcus mutans to enamel after vital bleaching.

OBJECTIVES: The purpose of this in vitro study was to observe the influence of vital bleaching on changes to the enamel surface and adhesion of Streptococcus mutans to tooth enamel. METHODS: The coronal part of each of 70 extracted third molars was cut in half, with either the buccal or lingual half used for experiments or controls. Experimental halves were assigned to the following conditions: (A) enamel was bleached 1, 3 or 5 times using a bleaching material with or without etching; or (B) etched condition without bleaching. All control samples were kept intact in physiological saline solution. Surface roughness (Ra; roughness center-line average: microm) of enamel was measured for 35 pairs of specimens. TS broth culture medium containing 3% glucose was inoculated with S. mutans and cultured for 72 h before adding the other 35 pairs of specimens. Under scanning electron microscopy, the number of S. mutans colonies was counted and statistically analysed. RESULTS: Compared to controls, bleached enamel displayed increased colonies of S. mutans. Repeated bleaching further increased bacterial adhesion and maximal colonies counts were found under conditions of five bleaching treatments plus etching (p</=0.01). Compared to controls, roughness increased after etching. However, no linear correlation was found between number of S. mutans colonies and roughness. CONCLUSION: We conclude that both surface roughness and adhesion of S. mutans to the enamel surface increase after bleaching.

Acid Etching, Dental↗

PubMed1984

Selection of Streptococcus mutans and lactobacilli in an intra-oral human caries model.

Microbiologic changes during caries development underneath a plaque-retaining band were investigated by the use of selective media for streptococci, Streptococcus mutans, and lactobacilli. The final four-week plaque samples on 16 experimental teeth in six young subjects were assessed. Seven experimental teeth in three other subjects were sampled at baseline and after one, two, and four weeks. All 23 experimental teeth developed a white spot lesion. In the final four-week plaque samples on the lesions, S. mutans accounted for 8% and lactobacilli 0.1% of the total CFU, both being significantly higher than in plaque from unbanded control surfaces. All experimental teeth sampled during lesion formation showed consistently elevated plaque levels of S. mutans and lactobacilli in comparison with baseline and control values at weeks one, two, and four. The results demonstrated a cariogenic environment in the human mouth associated with rapid selection of aciduric bacterial species such as S. mutans and lactobacilli.

Adolescent↗

PubMed1989

Uptake and expulsion of 14C-xylitol by xylitol-cultured Streptococcus mutans ATCC 25175 in vitro.

The effect of successive cultivations in the presence of 6% xylitol on the uptake and expulsion of 14C-xylitol was studied using the cells of Streptococcus mutans 25175. Three sequential cultivations did not alter the growth inhibition percentage (approximately 50%) observed in the presence of 6% xylitol. The 14C-xylitol uptake experiments performed with growing and resting cells showed that both the uptake and the expulsion of xylitol were enhanced by xylitol-culturing. Both xylitol-cultured and resting control cells contained only one major labeled compound which was identified as 14C-xylitol 5-phosphate. The label subsequently was expelled from the cells as 14C-xylitol. These results indicate that S. mutans possesses an intracellular xylitol cycle and this cycle is regulated by adding xylitol to the growth medium.

Carbon Radioisotopes↗

PubMed1985

Purification and characterization of a primer-independent glucosyltransferase from Streptococcus mutans 6715-13 mutant 27.

Affinity chromatography on Sephadex G-50 and subsequent ion-exchange chromatography on Trisacryl-M-DEAE were used to purify the glucosyltransferase (GTF) enzymes produced by mutant 27 of Streptococcus mutans 6715-13. Complete separation of three types of GTF, including a primer-independent GTF capable of synthesizing a slightly branched, water-soluble glucan (GTF-S), was obtained. The characteristics of this primer-independent GTF-S were compared with those of the normally occurring primer-dependent GTF-S. The Km for sucrose was easily obtained for each enzyme (10(-2) M), but the Km for dextran could only be determined for the primer-dependent GTF-S (5 X 10(-7) M for clinical dextran of molecular weight 60,000 to 90,000). The primer-independent GTF-S did not respond catalytically to the presence of either clinical dextran or the highly branched, water-soluble glucan produced by primer-dependent GTF-S, although it was capable of binding these polysaccharides at a noncatalytic site and of responding to the low-molecular-weight acceptor 1-O-methyl-alpha-D-glucopyranoside. The water-soluble glucan product of primer-independent GTF-S was a superior priming glucan for primer-dependent GTF enzymes as compared with the glucan product of primer-dependent GTF-S. The presence of primer-independent GTF-S in reaction mixtures stimulated glucan synthesis by primer-dependent GTF-S and by GTF synthesizing water-insoluble glucan by at least 10-fold, whereas the presence of similar amounts of primer-dependent GTF-S had no effect on synthesis by GTF synthesizing water-insoluble glucan. Primer-independent GTF-S appears to be a potent source of priming glucan for the primer-dependent GTF enzymes. Its possession of a noncatalytic binding site for glucan, the first observed for the GTF of S. mutans, suggests that it may also serve as a glucan receptor on the S. mutans cell surface.

Carbon Radioisotopes↗

PubMed2002

Enhanced immunogenicity of a genetic chimeric protein consisting of two virulence antigens of Streptococcus mutans and protection against infection.

The saliva-binding region (SBR) of the cell surface antigen I/II (AgI/II) and the glucan-binding region (GLU) of the glucosyltransferase enzyme of Streptococcus mutans have been implicated in the initial adherence of S. mutans to saliva-coated tooth surfaces and the subsequent sucrose-dependent accumulation of S. mutans, respectively. Here, we describe the construction and characterization of a genetic chimeric protein consisting of the two virulence determinants SBR and GLU (SBR-GLU). The effectiveness of this construct in inducing mucosal and systemic immune responses to each virulence determinant following intranasal immunization was compared to that of each antigen alone or an equal mixture of SBR and GLU (SBR+GLU) in a mouse model. Furthermore, the ability of antibodies induced to SBR-GLU to protect against S. mutans infection was also investigated. Immunization of mice with the chimeric protein SBR-GLU resulted in significantly enhanced (P < 0.001) levels of serum immunoglobulin G (IgG) anti-SBR antibody activity compared to those in the SBR and SBR+GLU groups. The SBR-GLU-immunized mice also demonstrated a significant (P < 0.05) increase in salivary and vaginal IgA antibody responses to SBR and GLU. Analysis of the serum IgG subclass responses to SBR in mice immunized with SBR alone indicated a mixed IgG1 and IgG2a response. A preferential IgG1 response compared to an IgG2a anti-GLU response was induced in mice immunized with GLU alone. Similarly, a preferential IgG1 response was also induced to SBR when GLU was present in either a mixed or conjugated form. Finally, a significant reduction (P < 0.05) in S. mutans colonization was observed only in mice immunized with the SBR-GLU chimeric protein. Taken together, our results indicate that the chimeric protein SBR-GLU significantly enhanced mucosal immune responses to SBR and GLU and systemic immune responses to SBR. The ability of SBR-GLU to induce responses effective in protection against colonization of S. mutans suggests its potential as a vaccine antigen for dental caries.

Administration, Intranasal↗

PubMed1993

The binding of delmopinol and chlorhexidine to Streptococcus mutans and Actinobacillus actinomycetemcomitans strains with varying degrees of surface hydrophobicity.

This study evaluated the binding of chlorhexidine and the new surface-active anti-plaque agent delmopinol hydrochloride to Streptococcus mutans and Actinobacillus actinomycetemcomitans cells with various cell surface hydrophobicities. The influence of saliva concentration on the binding of these compounds was also investigated. The radiolabeled compounds were incubated with bacteria and the cells were recovered using a centrifugal filtering technique. Delmopinol had higher binding to the hydrophilic variant strains than to the hydrophobic parent strains; chlorhexidine had higher binding to hydrophobic than to hydrophilic A. actinomycetemcomitans strains and higher binding to hydrophilic than to hydrophobic S. mutans strains. The presence of salivary films decreased the binding of both compounds. Both delmopinol and chlorhexidine had stronger affinity to A. actinomycetemcomitans cells than to S. mutans cells. At equimolar concentrations, delmopinol had a lower binding to all strains tested than chlorhexidine. The high reversibility of the delmopinol binding might be related to a higher diffusion rate and solubility compared with that of chlorhexidine. The amphiphilicity of both molecules is an important feature in their retention to S. mutans and A. actinomycetemcomitans strains of varying hydrophobicities and could play an important role in the substantivity of delmopinol or chlorhexidine in the oral cavity.

Aggregatibacter actinomycetemcomitans↗

PubMed2004

Modifications of hydrophobicity, in vitro adherence and cellular aggregation of Streptococcus mutans by Helichrysum italicum extract.

AIMS: The purpose of the present study was to examine whether sublethal concentrations of Helichrysum italicum extract could affect some of the cariogenic properties of Streptococcus mutans. METHODS AND RESULTS: We studied the antibacterial activity of H. italicum (ethanolic extract) against oral streptococci (Strep. mutans ATCC 35668, Strep. salivarius ATCC 13419 and Strep. sanguis ATCC 10556) and its influence on cell-surface hydrophobicity, in vitro sucrose-dependent adherence to glass surface and cellular aggregation of Strep. mutans. The results indicate that all streptococci were susceptible to ethanolic extract with minimum inhibitory concentration (MIC) values of 31.25-62.50 microg x ml(-1). Sub-MIC concentrations of H. italicum (7.81-31.25 microg x ml(-1)) reduced the hydrophobicity and the adherence (almost 90%) to glass surface of Strep. mutans. The aggregation in the presence of dextran T2000 was also affected. CONCLUSION: The inhibitory activity of H. italicum extract on Strep. mutans is worthy of further study. SIGNIFICANCE AND IMPACT OF THE STUDY: There is considerable interest in the use of natural compounds as alternative methods to control undesirable micro-organisms.

Anti-Bacterial Agents↗

PubMedDate not supplied

Lack of effect of chlorhexidine varnish on Streptococcus mutans transmission and caries in mothers and children.

In a randomized clinical trial, we evaluated the effect of a 10% chlorhexidine varnish (Chlorzoin) on the mother-child transmission of Streptococcus mutans and on subsequent caries experience. Chlorhexidine (n = 38) or a placebo varnish (n = 37) was applied to the dentitions of 75 mothers at a time when their first babies were about 6 months old (approximate time of first tooth emergence). Three more applications at weekly intervals and subsequent applications at 6-month intervals followed the initial application. The mother-child pairs were followed up until the child's fourth birthday. Maternal salivary S. mutans levels in the treatment group remained significantly lower (p < 0.05) compared to the control group up to 12 months after the initial application. However, this intervention did not significantly alter the S. mutans colonization in children or the caries increment in either the mother or the child.

Adolescent↗

PubMed1990

Interactions of selenium and fluoride on growth, glycolysis and survival of Streptococcus mutans GS-5.

The effects of low concentrations (1.0 mmol/l of selenite and seleno-dl-cystine were tested alone, or in combination with NaF, on growth, glycolysis, and survival of Streptococcus mutans GS-5. In batch culture, both selenium-containing compounds (1.0 mmol/l) inhibited the growth rate and final cell yield by 92% or greater; glycolysis, however, was not affected. The observed bactericidal action of selenite at 0.1 mmol/l was pH-dependent. Fluoride reduced the killing effect of SeO3 in the culture medium and in a lactate-acetate buffer system at pH 6.5, 5.0 and 4.0. These data indicate that selenium-containing compounds exert an antibacterial action on cells of S. mutans in a manner which leaves glycolysis unaffected.

Animals↗

PubMed1991

Inhibition of acid production by Streptococcus mutans NCTC 10449 by zinc and the effect of metal speciation.

Ionic zinc as zinc sulphate was strongly inhibitory to acid production from glucose by washed cell suspensions of Streptococcus mutans NCTC 10449 in a pH-stat assay (50% inhibition at 0.1 mM zinc). Zinc was adsorbed to the cells (up to 8 micrograms/mg cells). Several other zinc salts that dissociated to free zinc ions were also strongly inhibitory. Zinc in a partially complexed form as zinc citrate was less strongly inhibitory (50% inhibition at 0.2 mM zinc), and adsorption of zinc was lower (up to 3 micrograms/mg cells). Stoichiometric addition of ethylenediaminetetra-acetic acid (EDTA) to assays containing zinc sulphate completely removed inhibition and adsorption of zinc. A good correlation between inhibition of acid production and adsorption of zinc was found, and zinc adsorption was correlated with the levels of free zinc ion in the assay mixtures. The strongly anionic complexes of zinc, Zn(CIT)-, Zn(CIT)4-(2), and Zn(EDTA)2-, were not inhibitory and did not adsorb to the bacterial cells.

Acids↗