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PubMed1990

Sample, count, identify, and store the mutans streptococci.

According to a new method for sampling mutans streptococci, "Strip mutans", a plastic strip is contaminated by human saliva and incubated in a selective broth. After growth the strip with adherent colonies may be dried and stored. We wanted to know for how long a time bacteria in the colonies were viable if the strips were stored under different conditions. The survival time is important if the bacteria need to be subjected to further analyses. The results showed that the viability of the bacteria after the incubation period was at least 1 yr when the strips were stored frozen or frozen in glycerine. Stored dried in room temperature the survival was about 8 wk. A second part of the study aimed at identifying the colonies on strips obtained from different countries. Dried strips were sent air mail to our laboratory for biochemical and immunological analyses and the results showed that serotype/biotype c/e/f of S. mutans were most frequent but d/g S. sobrinus was also present in the samples, which came from Brazil, Greece, and Sweden. Three colonies of 213 on these strips did not grow, possibly indicating non-mutans bacteria.

Adolescent↗

PubMedDate not supplied

Modified oligosaccharides as potential dental plaque control materials.

Metabolic acids produced by oral pathogens demineralize tooth surfaces, leading to dental caries. Glucosyltransferases are the key factor in this process. We synthesized various modified oligosaccharides and tested them for their inhibitory effects on glucosyltransferase activity. Oligosaccharides were produced using a mixed-culture fermentation of Lipomyces starkeyi and Leuconostoc mesenteroides and then further modified as iron- and sulfate-oligosaccharides. Iron- and sulfate-oligosaccharides reduced glucosyltransferase activity of Streptococci from 17% to 43% and prevented the formation of insoluble biomass on the surface of glass vials or stainless steel wires in the presence of sucrose. They also reduced the growth and acid productions of oral pathogens including S. mutans, S. sobrinus, Eikenella corrodens, Prevotella intermedia, and Actinobacillus actinomycetemcmitans.

Animals↗

PubMed1989

[Microbiologic in vitro comparison of plaque-inhibiting mouthwashes].

The colonization on rat molars of S. sobrinus OMZ 176, S. mutans OMZ 376, or a combination S. sanguis OMZ 9 and S. sobrinus OMZ 176 after a short exposition to various fluoride solutions and disinfectants was tested in vitro. The test solutions included Act, Candida, Veadent, sodium fluoride, amine fluoride, stannous fluoride, zinc fluoride hexetidine, stannous fluoride/amine fluoride solutions, chlorhexidine and water. The sterilized rat molars were immersed in the above test solutions for 60 seconds, then incubated with streptococci in broth for 8 hours, again dipped into the same test solutions for 60 seconds and reincubated for an additional 30 hours. The streptococcal suspension contained 14C labelled sucrose solutions. The deposits on the molars were dissolved in 6N potassium hydroxide during 16 hours. Finally, the beta rays emitted by the dissolved radiolabelled suspension were counted using a scintillation counter. The sodium fluoride containing solutions exerted no or a very limited effect on the bacterial deposits. In contrast to the other test solutions, sanguinaria extract (Veadent mouth rinse) mildly inhibited the S. sobrinus and S. mutans deposits, but plaque formation by the combination of streptococci was not hampered. Zinc fluoride/hexetidine, amine fluoride and stannous fluoride/amine fluoride solutions had a distinct and significant inhibitory effect on S. sobrinus and S. mutans deposits, but only a weak effect when mixed cultures were used for plaque formation. Chlorhexidine significantly inhibited the deposits of the three bacterial strains used in these experiments.

Animals↗

PubMed2005

LuxS-based signaling affects Streptococcus mutans biofilm formation.

Streptococcus mutans is implicated as a major etiological agent in human dental caries, and one of the important virulence properties of this organism is its ability to form biofilms (dental plaque) on tooth surfaces. We examined the role of autoinducer-2 (AI-2) on S. mutans biofilm formation by constructing a GS-5 luxS-null mutant. Biofilm formation by the luxS mutant in 0.5% sucrose defined medium was found to be markedly attenuated compared to the wild type. Scanning electron microscopy also revealed that biofilms of the luxS mutant formed larger clumps in sucrose medium compared to the parental strain. Therefore, the expression of glucosyltransferase genes was examined and the gtfB and gtfC genes, but not the gtfD gene, in the luxS mutant were upregulated in the mid-log growth phase. Furthermore, we developed a novel two-compartment system to monitor AI-2 production by oral streptococci and periodontopathic bacteria. The biofilm defect of the luxS mutant was complemented by strains of S. gordonii, S. sobrinus, and S. anginosus; however, it was not complemented by S. oralis, S. salivarius, or S. sanguinis. Biofilm formation by the luxS mutant was also complemented by Porphyromonas gingivalis 381 and Actinobacillus actinomycetemcomitans Y4 but not by a P. gingivalis luxS mutant. These results suggest that the regulation of the glucosyltransferase genes required for sucrose-dependent biofilm formation is regulated by AI-2. Furthermore, these results provide further confirmation of previous proposals that quorum sensing via AI-2 may play a significant role in oral biofilm formation.

Bacterial Proteins↗

PubMed1992

A mechanism of passive immunization with monoclonal antibodies to a 185,000 M(r) streptococcal antigen.

The cell surface streptococcal antigen (SA) I/II of 185,000 M(r) is an immunodominant molecule that expresses one or more adhesion determinants. A series of 14 monoclonal antibodies (MAb) to defined parts of SA I/II were generated and some of these were used in passive immunization of macaques. Topical administration of selected MAb to the teeth of macaques prevented colonization of endogenous or implanted exogenous Streptococcus mutans for a period of 1 year. Significant reduction of both smooth surface and fissure caries was found in macaques who had MAb (Guy's 1) applied to their teeth, as compared with saline-treated animals. A series of in vivo passive immunization experiments was then carried out in 57 human subjects. Topical application of MAb to SA I/II prevented colonization of both artificially implanted exogenous strains of S. mutans, as well as natural recolonization by indigenous S. mutans. The properties of the protective MAb were then investigated and the epitope specificity within the SA I/II molecule was found to be essential but not the isotype specificity of the immunoglobulin (Ig). The requirement for complement activating and the phagocyte binding sites of the Fc fragment of MAb was not essential, as the F(ab')2 fragment of the MAb was as protective as the intact IgG, but the Fab fragment failed to prevent recolonization of S. mutans. Prevention of recolonization was specifically restricted to S. mutans, as the proportion of other organisms, such as S. sanguis, failed to show a significant change. The surprising feature of these experiments was that protection of re-colonization of S. mutans lasted up to 2 years, although MAb was applied for only 3 weeks and functional MAb was detected on the teeth only 3 days following application of the MAb. The long-term protection could therefore not be accounted for by a persistence of MAb on the teeth, but may be due to a shift in the microbial balance in which other bacteria occupy the ecological niche vacated by S. mutans, resulting in colonization resistance to S. mutans. Gene cloning and sequencing the SA from S. mutans, S. sobrinus and S. sanguis identified a conserved region (residues 955-1213) which on Southern hybridization and partial DNA sequence analysis was also found in 19 alpha-haemolytic oral streptococci. The results suggest that the SA molecule may constitute a family of adhesins in oral alpha haemolytic streptococci.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1986

Detection and specificity of antibodies secreted by spleen cells in mice immunized with Streptococcus mutans.

Immune responses of mice to Streptococcus mutans serotype c were analyzed by means of the enzyme-linked immunospot assay to determine the predominant specificities of the antibodies developed. In general, the numbers of splenic antibody-secreting cells correlated with serum antibody levels. A low dose (10(8) CFU) of killed whole cells injected twice intraperitoneally induced antibodies mainly against surface protein antigen I/II. A higher dose (10(9) CFU) given two to six times also resulted in a predominance of antigen I/II antibody-secreting cells and, in addition, antibody responses to surface protein antigen III and lipoteichoic acid occurred. Cells producing antibodies to serotype c polysaccharide were elicited only on repeated immunization. These results agreed with the development of antibodies in rabbits repeatedly immunized intravenously with killed whole cells of S. mutans, S. rattus, and S. sobrinus, which induced specific antibodies in accordance with the surface antigens that they express. Mice immunized twice with the same dose of purified antigens I/II and III developed greater numbers of antigen I/II splenic antibody-forming cells than antigen III splenic antibody-forming cells and higher serum antibody levels to antigen I/II than to antigen III. Furthermore, a single injection of antigen I/II but not of antigen III was sufficient to induce a strong specific-antibody response. Some evidence was also obtained for weak polyclonal stimulation of spleen cells by S. mutans cells and by antigen I/II, a result which could be relevant to the induction by S. mutans of antibodies reactive with mammalian tissues. It was concluded that for the antigens examined, S. mutans elicited the strongest antibody response against antigen I/II, which was also highly immunogenic in purified form.

Animals↗

PubMed1993

The resistance and adaptation of selected oral bacteria to mercury and its impact on their growth.

Selected strains of oral Streptococcus and Actinomyces have been tested for their ability to grow in the presence of mercury. Strains were tested for growth on a semi-defined medium with low mercury-binding characteristics. Sensitivities were initially measured on agar plates, and subsequently, selected strains were grown in broth so that the impact of mercury on the growth characteristics could be determined. Streptococci were more resistant to mercury (5 micrograms/mL to 40 micrograms/mL) than Actinomyces (< 5 micrograms/mL to 30 micrograms/mL). The most resistant streptococci included S. mitis biovar 1, S. salivarius, S. sobrinus, and one strain of S. mutans, all of which grew on agar with 40 micrograms/mL of mercury. Two other S. mutans strains were more sensitive, being inhibited by 10 and 20 micrograms/mL mercury. The most resistant Actinomyces was A. naeslundii genospecies 1 (ATCC12104), which grew on medium with 30 micrograms/mL mercury; two strains of Actinomyces were completely inhibited by 5 micrograms/mL. Mercury caused increased lag times and reduced cell density in broth cultures. Enrichment cultures of samples of human dental plaque showed that streptococci were the most resistant organisms that could be cultured on the medium and that these strains could adapt to relatively high mercury concentrations. S. oralis and S. mitis biovar 1 were the most resistant organisms isolated from enriched cultures, growing in broth media with 65 micrograms/mL mercury. Mercury was bound to cell walls and cell cytoplasm of streptococci grown in the presence of mercury.(ABSTRACT TRUNCATED AT 250 WORDS)

Amylases↗

PubMed2004

Genotypic analysis of strains of mutans streptococci by pulsed-field gel electrophoresis.

The species and serotypes of various strains of S. mutans and S. sobrinus were characterized by pulsed-field gel electrophoresis after the genomic DNA from the various strains had been digested with five restriction enzymes (EcoR I, Xba I, Hind III, Sfi I and BssH II) separately. Among these restriction enzymes, BssH II was very useful for the characterization of species and serotypes and, in particular, digestion discriminated between serotypes d and g. The restriction patterns obtained from the genomic DNA of isolates isolated from children's saliva were essentially identical to those from the genomic DNA of the standard laboratory strains. Patterns of BssH II digests of the genomic DNA of 10 isolates identified as S. sobrinus were characteristic of serotype g of the standard laboratory strains. Our results indicate that digestion with BssH II and subsequence analysis by pulsed-field gel electrophoresis should be useful for the characterization of species and serotypes and for epidemiological studies of mutans streptococci.

Adolescent↗

PubMed2001

Effect of removable orthodontic appliances on oral colonisation by mutans streptococci in children.

Little is known about the effect of removable orthodontic appliances on oral colonisation by mutans streptococci (MS). In the present study, the frequency of isolation and serotype distribution of MS were evaluated in two groups of children, one undergoing therapy with removable appliances and the other not subjected to any kind of orthodontic treatment, respectively. Streptococci isolated from dental plaque samples from both groups of children were identified as mutans streptococci on the basis of their morphological and biochemical properties and were then serotyped in an enzyme immuno-assay using monoclonal antibodies. The number of subjects harbouring MS in their dental plaque was statistically higher in the group of orthodontic children without caries experience (CF) in comparison with CF children of the control group (10/12, 83.3% vs. 15/44, 34%). No clear difference was observed in the distribution of the different MS serotypes between the experimental and control group: S. mutans c,f serotype was the most frequently isolated in both groups of children followed by S. mutans serotype e and S. sobrinus serotype g. Such results suggest that the use of removable appliances may lead to the creation of new retentive areas and surfaces, which favour the local adherence and growth of MS. The data obtained stress the importance of a careful monitoring of patients treated orthodontically for risk of caries development.

Case-Control Studies↗

PubMed1993

First characterization in Italy of clinical isolates of mutans streptococci by using specific monoclonal antibodies.

The aim of this investigation was to gain further insight into the prevalence of different serotypes of mutans streptococci in the Italian population by using specific monoclonal antibodies in an enzyme immunoassay. Isolates from dental plaque samples, collected from an adult population living in Pisa (Italy), were identified as mutans streptococci on the basis of their morphological and biochemical properties, and were then serotyped. The results show that 77.5% of the strains isolated belonged to serotype c or f (i.e., S. mutans), 15.9% were serotype e (i.e., S. mutans) and only two strains (1.4%) belonged to serotype g (i.e., S. sobrinus). These data are partially in agreement with other studies in Europe and in the U.S.A. The distribution pattern of the various serotypes turned out to be substantially similar among the different groups of patients, subdivided on the basis of their caries status, indicating that none of the serotypes was particularly associated with dental caries.

Adolescent↗

PubMed1989

Aggregation of 27 oral bacteria by human whole saliva. Influence of culture medium, calcium, and bacterial cell concentration, and interference by autoaggregation.

Twenty-seven oral strains of the genera Actinomyces (5), Bacteroides (3), and Streptococcus (19) were tested for aggregation by human whole saliva, as well as the effect of culture medium, Ca-ions, and bacteria concentration thereupon. Of the media tested, GF-broth gave rise to less interference by autoaggregation or higher aggregation titers than BHI and TSB, and was used throughout this study. In most cases, Ca-ions (1 mM) only enhanced the rate of induced aggregation, whereas raising the bacteria concentration increased the rate of both induced- and autoaggregation. The final titers, ranging from 1-64, were hardly affected by these parameters, except those of S. rattus HG 59 and S. mutans HG 199, which were respectively increased and decreased by Ca-ions. Saliva-induced aggregation was observed for 21 strains of A. viscosus, A. naeslundii, A. israelii, B. gingivalis, B. intermedius, S. cricetus, S. mutans, S. rattus, S. sanguis, and S. sobrinus, mostly within 15 min to 3 h. Seventeen of these strains also showed autoaggregation, usually well after the onset of induced aggregation. Any potential induced aggregation of B. gingivalis HG 91 was always masked by autoaggregation, as well as that of the S. mutans strains under a particular set of conditions. The aggregation rate and titer varied considerably in a mutually unrelated and strain-dependent way. These microtiterplate data were matched by the 5 spectrophotometric patterns observed for saliva-bacterial interaction, which moreover, gave the better differentiation between induced and autoaggregation. In conclusion, most strains tested can show rapid saliva-induced aggregation in a strain-dependent way, yet strongly affected by the experimental conditions and interference from autoaggregation.

Animals↗

PubMed1998

Identification of streptococci to species level by sequencing the gene encoding the manganese-dependent superoxide dismutase.

We have used a PCR assay based on the use of degenerate primers in order to characterize an internal fragment (sodA(int)) representing approximately 85% of the genes encoding the manganese-dependent superoxide dismutase in various streptococcal type strains (S. acidominimus, S. agalactiae, S. alactolyticus, S. anginosus, S. bovis, S. constellatus, S. canis, S. cricetus, S. downei, S. dysgalactiae, S. equi subsp. equi, S. equi subsp. zooepidemicus, S. equinus, S. gordonii, S. iniae, S. intermedius, S. mitis, S. mutans, S. oralis, S. parasanguis, S. pneumoniae, S. porcinus, S. pyogenes, S. salivarius, S. sanguis, S. sobrinus, S. suis, S. thermophilus, and S. vestibularis). Phylogenetic analysis of these sodA(int) fragments yields an evolutionary tree having a topology similar to that of the tree constructed with the 16S rRNA sequences. We have shown that clinical isolates could be identified by determining the positions of their sodA(int) fragments on the phylogenetic tree of the sodA(int) fragments of the type species. We propose this method for the characterization of strains that cannot be assigned to a species on the basis of their conventional phenotypic reactions.

Base Sequence↗

PubMed2001

Automated fluorescent in situ hybridization for the specific detection and quantification of oral streptococci in dental plaque.

Our aim was to develop a rapid fluorescent in situ hybridization (FISH) assay for the identification of different oral groups of streptococci in dental plaque and to combine it with digital image analysis for the automated enumeration of target cells. Cy3-labeled oligonucleotide probes specific for 16S rRNA gene sequences of the anginosus, mitis, mutans, and salivarius groups of streptococci were hybridized under stringent conditions with bacterial cultures or supragingival plaque samples that had been permeabilized with lysozyme. Probe specificity was determined with strains from 30 different species, mainly of oral origin. Results showed that probes ANG541, MIT447, SSP001, and SAL090 with specificity for the anginosus, mitis, mutans, and salivarius groups, respectively, the pan-reactive streptococcal probe STR405, the S. mutans specific probe MUT590, and the S. sobrinus specific probe SOB174 were well-suited for the identification of cultured streptococci. Probes STR405, MIT447 and SSP001 were then successfully applied to enumerate automatically bacteria of the recognized taxa in 144 supragingival plaque samples. On the average, total streptococci accounted for 8.2%, streptococci of the mitis and mutans groups for 3.9 and 1.7%, respectively, of the plaques. The combined application of FISH and automated image analysis provides an objective time-saving alternative to culture or PCR for the enumeration of selected oral streptococci in dental plaque.

Colony Count, Microbial↗

PubMed1991

[The establishment efficiency of S. sobrinus OMZ 176 in a model caries experiment on the Osborne-Mendel rat].

S. sobrinus OMZ 176 was inoculated in young OM rats during tooth eruption in two experiments and the microbial composition of dental plaque as well as the caries decay was estimated after 25 days on cariogenic sucrose rich diet. Germs were reproducibly established in the oral cavity by such way. The resulting caries decay correlated with the streptococci in the dental plaque. Due to this fact it seems to be necessary to identify not only the inoculated microorganisms at the end of each animal experiment but also to estimate the qualitative composition of the whole dental flora which may have an essential cariogenic effect.

Animals↗

PubMedDate not supplied

Antibacterial activity of dentin bonding systems, resin-modified glass ionomers, and polyacid-modified composite resins.

The antibacterial effects of the dentin bonding systems Syntac, ProBOND, Gluma 3-Step, the resin-modified glass ionomers Photac-Fil, Fuji Lining LC, Fuji II LC, and the polyacid-modified composite resins VariGlass, Geristore, and Infinity were evaluated using the cariogenic bacteria S mutans, L salivarius, S sobrinus, and A viscosus in vitro with a modified cylinder drop plate agar diffusion assay. All glass ionomers, the polyacid-modified composites, and the primers and adhesives of the dentin bonding systems exhibited various degrees of antibacterial activity against most of the test bacteria. The antibacterial activity of the adhesives of dentin bonding systems was anticipated because of the glutaraldehyde used in their formulations. However, the antibacterial activity of the various primers was unexpected and indicates a dual antibacterial action of these systems.

Acrylic Resins↗

PubMed1990

[Non-cariogenicity of erythritol as a substrate].

Erythritol is a sugar alcohol which is obtained through a cultivation of glucose and Aureobasidium sp. The sugar is about 70-80% as sweet as sucrose and is also non-hygroscopic. The effect of erythritol on cariogenicities of mutans streptococci (serotype a-h) and certain oral microorganisms was studies. Erythritol was not utilized as a substrate for the growth, lactic acid production and plaque formation of mutans streptococci (serotype a-h). It did not serve as a substrate for cellular aggregation of mutants streptococci (serotype d, g, h) and was not utilized water-insoluble glucan synthesis and cellular adherence by glucosyltransferase from S. mutans PS-14 (c) or S. sorbrinus 6715 (g). Erythritol was not also utilized for the growth and lactic acid production of certain oral microorganisms although some growth was seen with Actinomyces viscosus. SPF SD rats infected with S. sobrinus 6715 were fed a diet containing 26% erythritol or 26% sucrose for 53 days. A significantly (p less than 0.01) lower caries score (mean +/- SE; 3.1 +/- 0.5) was observed in the rat fed a diet containing erythritol than the control (60.5 +/- 2.0). The caries inhibition rate is 94.9%. Also, rats infected with S. mutans PS-14 were fed a diet containing 56% erythritol chocolate or 56% sucrose chocolate for 58 days. The mean total caries score of rats fed a diet containing 56% erythritol chocolate was 6.7 +/- 0.8, while the mean total caries score of rats fed a diet containing 56% sucrose chocolate was 82.8 +/- 2.8. The value between both groups was significant at 0.01 level, and the caries inhibition rate is 91.9%.

Actinomyces viscosus↗

PubMed1989

Antimicrobial and antiplaque effects of a chlorhexidine and Triton X-100 combination.

This study aimed to assess the in vitro antimicrobial effect and in vivo plaque-inhibiting capacity of chlorhexidine (CH) combined with the nonionic detergent Triton X-100. Synergistic inhibition was observed by the combination of Triton X-100 and CH on in vitro growth of S. sobrinus OMZ 176 and of S. sanguis 10556. In the clinical experiments, 10 subjects rinsed twice daily with 10 ml aqueous solutions of 11.6 mM Triton X-100, and 0.55 mM CH, and with a combination of the two agents. All mechanical oral hygiene was suspended during the test periods. Sucrose enhanced plaque accumulations were recorded after 4 days of rinsing. The combination of CH-Triton X-100 decreased plaque accumulations significantly compared to placebo, but was less effective than CH alone (P less than 0.05). Thus no beneficial clinical effect was gained by combining the nonionic agent Triton X-100 with the cationic agent CH. The results also clearly demonstrate that addition which increase the antibacterial activity of CH do not necessarily coincide with improved in vivo antiplaque efficacy.

Chlorhexidine↗

PubMed1989

On dental health in Icelandic children. Observations during a clinical dentifrice trial.

Dental health and the relative caries preventive effect of different fluoride dentifrice formulations were assessed in an Icelandic child population. For a cross sectional study 1370 children, aged 11 and 12 years were examined for caries and periodontal conditions employing standardized methods. Longitudinal data were obtained from 1161 children, participating in a three-year dentifrice trial. Randomly selected subgroups were employed to study salivary levels of mutans streptococci and lactobacilli, consumption of high-sucrose products and enamel fluoride content in relation to caries experience. Relative caries preventive effect of anticalculus agents (HEBP and AHBP) and lowered fluoride concentration (250 ppm) in dentifrices were evaluated in a three-year double blind randomized clinical trial. At the baseline examination a comparatively high mean caries prevalence (DFS 9.9) was registered. Longitudinal observations showed a mean caries increment of 10.5 surfaces during a three-year period. Simultaneously an improvement of gingival health was observed. A majority of children harbored mutans streptococci (98%) and lactobacilli (92%). High numbers of either microorganism were associated with high caries prevalence. S. sobrinus carriers were more frequent among children with high numbers of CFU per ml saliva. The consumption of sugar-containing products was generally frequent. Higher caries increment was associated with consumption of sweets and bakery products during mealtimes. The fluoride content of surface enamel was comparatively low, reflecting scarce post eruptive exposure. Dentifrice, containing 250 ppm fluoride showed significantly lower caries preventive effect compared to 1000 ppm sodium fluoride and MFP formulations. Addition of anticalculus agents (biphosphonates) had no negative effect on reducing caries increment. These studies show that dental caries constitutes a major health problem among Icelandic children, where high sugar consumption and comparatively low exposure to fluoride appear to play major roles. The use of fluoride dentifrice has not been able to limit caries development.

Child↗