SEARCH · PubMed Health

Results for “Streptococcus sobrinus”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources

PubMed1992

Mode of photocatalytic bactericidal action of powdered semiconductor TiO2 on mutans streptococci.

Powdered semiconductor TiO2 has a photocatalytic bactericidal capacity on some kinds of bacteria, but its mechanism still remains unclear. The mode of its photocatalytic bactericidal action on the mutans group of streptococci was investigated. Powdered TiO2 had a bactericidal capacity on all serotypes of mutans streptococci. Streptococcus sobrinus AHT was mainly used for these experiments. The most effective concentration of TiO2 was about 1 mg ml-1 and, at this concentration, 10(5) colony-forming units of S. sobrinus AHT per millilitre were completely killed within 1 min. In order to search for the mechanism of this effect, a high bacterial cell density (10(9) colony-forming units ml-1) was used in the following studies. "Rapid" leakage of potassium ions from the bacteria occurred parallel to the decrease in cell viability. Protein and RNA were "slowly" released from bacterial cells for a reaction time up to 120 min. The pH of the reaction mixture decreased continuously to 4.5 after 120 min. Co-aggregation of S. sobrinus AHT and powdered TiO2 occurred at high bacterial densities (above 10(8) colony-forming units ml-1). Aggregates gradually decomposed with light irradiation. Transmission electron microscopy of S. sobrinus AHT after photocatalytic action for 60-120 min indicated complete destruction of bacterial cells. From these results, bacterial death appears to be caused by a significant disorder in cell membranes and finally the cell walls were decomposed.

Hydrogen-Ion Concentration↗

PubMed1981

Colonization and cariogenicity of Streptococcus ferus in rats.

Streptococcus ferus, which is indigenous to wild rats, is a member of the mutans group of streptococci. We tested its ability to colonize and to cause caries in laboratory rats by comparing two strains of S. ferus with the very cariogenic Streptococcus sobrinus strain 6715. Groups of rats were fed either finely ground mouse chow or a 56% sucrose diet, or they were switched from chow to the sucrose diet. All three strains colonized the mouths of rats regardless of diet. However, the infectants reached higher proportions of the total flora more quickly in the rats consuming sucrose. Similarly, the percentage of the oral flora represented by an infecting organism increased numerically when rats originally fed chow were switched to the sucrose diet. S. ferus formed plaques on the teeth of the rats, but these plaques did not proliferate over smooth tooth surfaces as extensively as did those of S. sobrinus. Although S. ferus colonized and accumulated, it was non-cariogenic in rats fed sucrose compared both with rats fed similarly but infected with S. sobrinus 6715 and with uninfected controls. In vitro measurements suggested the S. ferus produced acid less rapidly than S. sobrinus. Thus, the lack of cariogenicity in S. ferus may result from an inability to form copious plaques on smooth tooth surfaces and from low acid production and, therefore, may represent a natural absence of the pathogenic potential usually inherent in the mutans streptococci.

Animal Nutritional Physiological Phenomena↗

PubMedDate not supplied

Fluoride release and antibacterial properties of new-generation tooth-colored restoratives.

The aim of this study was to compare the amounts and pattern of fluoride release and antibacterial properties of new-generation restoratives over a 35-day period. Materials evaluated included fluoride-releasing composites (Tetric, Experimental X), compomers (Dyract, Compoglass), and a resin-modified glass-ionomer cement (Fuji II LC). A conventional glass ionomer (Fuji II Cap) was used as a control for fluoride-release testing. Five samples of each restorative material were evaluated for daily fluoride release over a 35-day period by means of ion chromatography. Ranking of materials from least to greatest total fluoride release over 35 days was as follows: Tetric < Experimental X < Dyract < Fuji II LC < Compoglass < Fuji II Cap. Fuji II Cap had significantly greater fluoride release than all other materials evaluated. Fuji II Cap, Fuji II LC, and Compoglass had similar patterns of fluoride release characterized by a high initial release that was many times that released later. The fluoride-releasing composites evaluated stopped releasing fluoride by day 14. Antibacterial testing was conducted using the agar diffusion inhibitory test. Five samples of each restorative were assessed at baseline and weekly intervals up to 35 days. The microorganisms used were Lactobacillus casei, Streptococcus mutans, and Streptococcus sobrinus. IRM, a zinc oxide/eugenol cement, was used as the baseline control. None of the restorative materials evaluated affected the growth of L casei, S sobrinus, or S mutans at all time periods including baseline, where fluoride was detected in the agar beneath the specimen disks. There was no correlation noted between fluoride-release potential and antibacterial properties.

Anti-Infective Agents, Local↗

PubMed1990

Gingival overgrowth induced by cyclosporin A in rats.

Gingival overgrowth, which is one of the major side-effects of this immunosuppressive agent, was studied in specific pathogen-free Fischer rats fed diet No. 2000 containing 56% sucrose. Marked macroscopic overgrowth was noted in mandibular gingiva of all the rats fed this diet containing cyclosporin A. The overgrowth was more severe in buccal than in lingual gingiva. Rats fed the cyclosporin-containing diet and infected with Streptococcus sobrinus 6715 had the most gingival overgrowth. Histopathological examination revealed that the bulk of the enlargement consisted of fibrous connective tissue without a marked increase in the number of fibroblasts or inflammatory cells.

Animals↗

PubMed1989

[Caries-inducing activity of isomaltooligosugar (IMOS) in in vitro and rat experiments].

The caries-inducing activity of Isomaltooligosugar (IMOS: a isomaltose rich sugar mixture) was examined in in vitro and in vivo experiments. Strains of Streptococcus mutans MT8148R and Streptococcus sobrinus 6715 fermented IMOS and produced acids. IMOS inhibited the glucan synthesis from sucrose by glucosyltransferases from both of S. mutans and S. sobrinus. Furthermore, IMOS inhibited sucrose-dependent adherence of those mutans streptococci. IMOS was found to induce significant but minimal caries SPF Sprague-Dawley rats infected with either MT8148R and 6715. However, IMOS did not inhibit the caries which was induced by sucrose.

Animals↗

PubMed1996

Initial pH as a determining factor of glucose consumption and lactic and acetic acid production in oral streptococci.

Lactic and acetic acid production was evaluated from six strains of oral streptococci, viz Streptococcus gordonii, Streptococcus mutans, Streptococcus oralis, Streptococcus salivarius, Streptococcus sanguis and Streptococcus sobrinus cultured in the presence of 1, 5, 10 mM glucose and without glucose, at initial pH values of 5, 5.5, 6 and 7. S. sobrinus and S. salivarius caused the greatest decreases in pH. At pH values of 5 and 5.5, lactic acid and acetic acid production in the species tested was discordant with residual glucose levels. Acid production from protein was especially great in S. mutans and S. salivarius.

Acetic Acid↗

PubMed1988

Colonization of rat molar teeth by mutans streptococci with different salivary agglutination characteristics.

The oral implantation of salivary agglutination-positive and -negative mutans streptococci was studied using streptomycin resistant (StrR) organisms. StrR Streptococcus mutans strains Ingbritt and NCTC 10449 are agglutinated by rat saliva and the StrR strains Streptococcus sobrinus 6715-13 and Strep. mutans GS5 are not. Four groups of Sprague-Dawley rats were inoculated orally with each organism (one per group) and fed a sucrose diet. A further two groups of animals were similarly inoculated with either the agglutination-positive Strep. mutans Ingbritt or the agglutination-negative Strep. sobrinus 6715-13 and fed a glucose diet. StrR streptococci were recovered from smooth-surface dental plaque of all animals on the sucrose diet with no significant difference in the recovery of agglutination-positive Strep. mutans strains Ingbritt and NCTC 10449 and agglutination-negative Strep. mutans GS5. However, the recovery of agglutination-negative Strep. sobrinus 6715-13 from smooth-surface plaque of animals on either the sucrose or the glucose diets was significantly lower than that of the other strains. Agglutination-positive Strep. mutans Ingbritt colonized smooth enamel surfaces of animals on the sucrose and the glucose diets in numbers that were not significantly different. However, the colonization of such surfaces by agglutination-negative Strep. sobrinus 6715-13 was significantly enhanced by the sucrose diet. Agglutination-positive and -negative StrR mutans streptococci were recovered from fissure plaque of all inoculated sucrose-fed animals in numbers that were not significantly different. Successful colonization of smooth enamel surfaces by the StrR streptococci resulted in increased smooth-surface caries.(ABSTRACT TRUNCATED AT 250 WORDS)

Agglutination↗

PubMed1990

Salivary conditions and cariogenic microorganisms in 55, 65, and 75-year-old Swedish individuals.

Secretion rate, buffer capacity, and cariogenic microorganisms of resting and stimulated whole saliva were examined in 208 55-, 65-, and 75-yr-old Swedes. The secretion rate for both resting and stimulated saliva decreased with age. When the use of drugs was taken into account the difference in terms of age group was significant for resting saliva alone (P less than 0.01). In 22% the resting saliva was less than 0.1 ml/min, and in 5% the stimulated saliva was less than 0.7 ml/min. Persons with subjective dryness in the mouth had a lower salivary flow. Men had higher secretion rates than women irrespective of medication (P less than 0.05). The buffer capacity was strongly correlated to the secretion rate of both resting and stimulated saliva (r = 0.39 and r = 0.44, respectively). The number of mutans streptococci and lactobacilli increased with age, although significant in terms of age group for lactobacilli alone (P less than 0.05). The number of these microorganisms was lower in resting saliva than in stimulated saliva (P less than 0.0001). Individuals harboring both Streptococcus mutans and Streptococcus sobrinus had higher values of mutans streptococci in resting and stimulated saliva than those harboring only S. mutans (P less than 0.001). Actinomyces viscosus and Actinomyces naeslundii comprised greater than or equal to 1% of the total CFU in 89% of the plaque samples. The corresponding figures for lactobacilli and mutans streptococci were 6% and 38%, respectively.

Actinomyces↗

PubMed1995

A comparison of the microbial flora in carious dentine of clinically detectable and undetectable occlusal lesions.

It is not known whether the aetiology of occlusal hidden caries lesions (HCL) is identical to that of small visible lesions (SVL). Previous studies of the microflora of HCL suggest that relatively few species can be isolated. The aim of the present study was to compare the bacterial composition of dentine from 10 HCL and 17 SVL in a population of children aged 8-18 years. The following bacteria were identified: Actinomyces spp., mutans streptococci, Streptococcus sanguis, Streptococcus oralis, Streptococcus gordonii. Streptococcus mitis, and Lactobacillus spp. Streptococcus mutans was found more often in the HCL group (p = 0.03), while Streptococcus sobrinus was found more often in the SVL group (p = 0.05). However, proportions of both species were lower in the SVL group as compared with the HCL group (S. mutans p = 0.07; S. sobrinus p = 0.03). Lactobacilli and Actinomyces spp. were found at similar levels in both groups. A more diverse range of streptococcal species and Veillonella was found in the SVL group (p = 0.001). These results show a less complex microflora in HCL as compared with SVL, indicating that the aetiology of hidden caries might be different from that of open caries.

Actinomyces↗

PubMed1986

In vitro studies of growth and competition between S. salivarius TOVE-R and mutans streptococci.

Streptococcus salivarius TOVE-R has previously been reported as a successful competitor with Streptococcus mutans 10449S and Streptococcus sobrinus 6715-13 WT on the teeth of rats. We studied, in vitro, some possible bases for this competition, including hydrogen peroxide or catalase production, bacteriocin or enocin production, and growth rates. Growth rates were measured spectrophotometrically in both complex and defined media. We studied conditions of aerobic and anaerobic incubation; glucose and sucrose medium supplementation at three concentrations each; various initial pH's; singly- or doubly-inoculated cultures; and half-strength, normal, or double-strength broth used both fresh and as culture filtrates. TOVE-R grew as well as did mutans streptococci at acid pH, decidedly better at alkaline pH, and nearly twice as fast near neutral pH. The average doubling time for TOVE-R was about 0.5 hr, while that for the mutans streptococci was about 1.0 hr. When TOVE-R was grown together with a mutans streptococcus, the growth rate observed for the doubly-inoculated culture was equal to or less than that of TOVE-R alone, never greater. The presence and proportions of both organisms in mixed cultures were confirmed by plate counts, direct specific immunofluorescence, and Nomarski interference microscopy. There was no evidence, by any of the methods employed, to indicate the production of an inhibitory substance against mutans streptococci by TOVE-R, or vice versa. Also, there was no evidence that the faster growth rate of TOVE-R could be attributed to nutrient limitation of the mutans streptococci.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaerobiosis↗

PubMed2004

The influence of mutanase and dextranase on the production and structure of glucans synthesized by streptococcal glucosyltransferases.

Glucanohydrolases, especially mutanase [alpha-(1-->3) glucanase; EC 3.2.1.59] and dextranase [alpha-(1-->6) glucanase; EC 3.2.1.11], which are present in the biofilm known as dental plaque, may affect the synthesis and structure of glucans formed by glucosyltransferases (GTFs) from sucrose within dental plaque. We examined the production and the structure of glucans synthesized by GTFs B (synthesis of alpha-(1-->3)-linked glucans) or C [synthesis of alpha-(1-->6)- and alpha-(1-->3)-linked glucans] in the presence of mutanase and dextranase, alone or in combination, in solution phase and on saliva-coated hydroxyapatite beads (surface phase). The ability of Streptococcus sobrinus 6715 to adhere to the glucan, which was formed in the presence of the glucanohydrolases was also explored. The presence of mutanase and/or dextranase during the synthesis of glucans by GTF B and C altered the proportions of soluble to insoluble glucan. The presence of either dextranase or mutanase alone had a modest effect on total amount of glucan formed, especially in the surface phase; the glucanohydrolases in combination reduced the total amount of glucan. The amount of (1-->6)-linked glucan was reduced in presence of dextranase. In contrast, mutanase enhanced the formation of soluble glucan, and reduced the percentage of 3-linked glucose of GTF B and C glucans whereas dextranase was mostly without effect. Glucan formed in the presence of dextranase provided fewer binding sites for S. sobrinus; mutanase was devoid of any effect. We also noted that the GTFs bind to dextranase and mutanase. Glucanohydrolases, even in the presence of GTFs, influence glucan synthesis, linkage remodeling, and branching, which may have an impact on the formation, maturation, physical properties, and bacterial binding sites of the polysaccharide matrix in dental plaque. Our data have relevance for the formation of polysaccharide matrix of other biofilms.

Bacterial Adhesion↗

PubMed1992

Adhesion of mutants streptococci to glass with and without a salivary coating as studied in a parallel-plate flow chamber.

Deposition and adhesion to glass with and without a salivary coating in a parallel-plate flow chamber were studied with four strains of mutans streptococci. Stationary-state adhesion of the strains to uncoated glass ranged from 0.3 x 10(6) cm-2 (Streptococcus rattus HG218) to 12.7 x 10(6) cm-2 (Streptococcus sobrinus HG1025) and generally decreased after saliva coating of the glass. The poor adhesion found for S. rattus HG218 to both uncoated and saliva-coated glass could be due to its relatively high negative surface-charge. Deposition efficiencies of all strains were greater than or equal to 1 for uncoated glass and decreased greatly after saliva coating of the glass. Possibly, adhesion to a saliva coating is less efficient and more time-consuming than that to uncoated glass, because stereochemical groups in the pellicle and on the cell surfaces may have to re-arrange before an effective interaction can occur. Desorption rates, measured 1000 s and 5000 s after the start of an experiment, decreased by a factor of ten upon a five-fold increase in contact time, indicative of a two-phase adhesion process. Of the four strains studied, only Streptococcus cricetus HG737 showed a minor positive cooperativity on saliva-coated glass, possibly mediated by surface appendages observed by transmission electron microscopy on negatively-stained cells. Retention of adhering bacteria was strain-dependent on uncoated glass, but was identical for all strains on saliva-coated glass, which suggests that the structure and composition of the pellicle may be more important with respect to the retention of adhering cells than the cell-surface properties themselves.

Bacterial Adhesion↗

PubMed1991

Partial characterization of the glucosyltransferases of an oral Streptococcus salivarius strain.

The oral Streptococcus salivarius strain S3 possessed extracellular glucosyltransferase (GTF) and cell-associated fructosyltransferase activities. Chromatofocusing column chromatography of crude GTF yielded multiple peak fractions, which were categorized into two types which catalysed (1) water-insoluble glucan synthesis and (2) water-soluble glucan formation. The GTF isozyme eluted in fraction 29 synthesized mutanase- and dextranase-sensitive insoluble glucan from sucrose, while fraction 81 GTF synthesized soluble glucan which was insensitive to both glucanases. The ability to agglutinate Streptococcus sobrinus cells was high for insoluble glucan but negligible for soluble glucan. The insoluble glucan-synthesizing activity of fraction 29 GTF was inhibited by the presence of dextran T10. Isoelectric focusing yielded a single activity band but SDS-polyacrylamide gel electrophoresis gave multiple bands for both GTF fractions 29 and 81. The extracellular crude GTF activity was inactivated by 0.1% SDS or 1% Tween 80, but the activity was completely restored by the addition of 1% Triton X-100.

Detergents↗

PubMed1990

Human strains of mutans streptococci show different cariogenic potential in the hamster model.

The cariogenic potential of fresh humans strains of Streptococcus mutans and Streptococcus sobrinus was examined in hamsters maintained on a high sucrose diet. The strains 1B 16 (S. mutans) and B13 (S. sobrinus) isolated 20-25 yrs ago served as positive controls. Three series of experiments were run. Some strains were tested once and some strains were tested in all 3 experiments. The animals infected with S. sobrinus strains generally showed lower caries scores than those infected with S. mutans strains. Among the groups infected with the different strains of S. mutans the caries scores varied. In one of the experiments the caries score of the animals infected with one of the Icelandic S. mutans strains was significantly higher than that of the positive control group and the group infected with one of the fresh Swedish isolates. Thus, different strains of mutans streptococci where shown to induce varying caries activity in the hamster model.

Adolescent↗

PubMed1995

Insertional inactivation of the Streptococcus mutans dexA (dextranase) gene results in altered adherence and dextran catabolism.

Streptococcus mutans is able to synthesize extracellular glucans from sucrose which contribute to adherence of these bacteria. Extracellular dextranase can partially degrade the glucans, and may therefore affect virulence of S. mutans. In order to isolate mutants unable to produce dextranase, a DNA library was constructed by inserting random Sau3AI-digested fragments of chromosomal DNA from S. mutans into the BamHI site of the streptococcal integration vector pVA891, which is able to replicate in Escherichia coli but does not possess a streptococcal origin of replication. The resultant plasmids were introduced into S. mutans LT11, allowing insertional inactivation through homologous recombination. Two transformants were identified which did not possess dextranase activity. Integration of a single copy of the plasmid into the chromosome of these transformants was confirmed by Southern hybridization analysis. Chromosomal DNA fragments flanking the plasmid were recovered using a marker rescue technique, and sequenced. Comparison with known sequences using the BLASTX program showed 56% homology at the amino acid level between the sequenced gene fragment and dextranase from Streptococcus sobrinus, strongly suggesting that the S. mutans dextranase gene (dexA) had been inactivated. The colony morphology of the dextranase mutants when grown on Todd-Hewitt agar containing sucrose was altered compared to the parent strain, with an apparent build-up of extracellular polymer. The mutants were also more adherent to a smooth surface than LT11 but there was no apparent difference in sucrose-dependent cell-cell aggregation.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1990

Construction of NotI restriction map of the Streptococcus mutans genome.

Streptococcus mutans and Streptococcus sobrinus are the major causative organisms of human dental caries. Pulsed-field gel electrophoresis (PFG) showed that the restriction enzyme NotI produced ten and six DNA fragments from the genomes of S. mutans strain MT8148 and S. sobrinus strain 6715, respectively. The sizes of the chromosomes of S. mutans and S. sobrinus were each estimated to be about 2200 kb. The NotI restriction map of S. mutans MT8148 genome was constructed by Southern blot analysis with probes that overlapped two adjacent NotI fragments. Several virulence-associated genes of S. mutans were placed on the NotI restriction map. In addition, unique 'fingerprints' of S. mutans chromosomal DNA digested with NotI were produced by PFG, and these may be useful for epidemiological studies.

Base Sequence↗

PubMed1990

Dental caries in congenitally athymic rats.

The importance of the immune response in dental infection was evaluated in heterozygous (rnu/+) normal and homozygous (rnu/rnu) congenitally athymic "nude" Rowett rats. Animals of both types were infected, or immunized and infected, with mutans streptococci (Streptococcus sobrinus strain 6715). The mean numbers of S. sobrinus cells recovered from the nude rats were higher than those from comparable (immune/nonimmune) normal rats in 10 of 12 possible comparisons. Also, S. sobrinus constituted a greater percentage of the total streptococci in the nude rats compared with normal animals (6 of 6 possible comparisons). Antibody to S. sobrinus whole cells or to S. sobrinus glucosyltransferase from nude rats in serum or in saliva was significantly lower (or absent) than that of comparable normal rats. This was seen after infection, but was most pronounced after immunization (and infection). Dental caries was also significantly elevated in the congenitally athymic animals. Immunologic deficiency of congenitally athymic rats can lead to a greater infection level with mutans streptococci and increased dental caries.

Analysis of Variance↗

PubMed1991

Immunogenicity and protective effect against oral colonization by Streptococcus mutans of synthetic peptides of a streptococcal surface protein antigen.

Streptococcus mutans is known to be a major causative organism of human dental caries. A surface protein Ag with a molecular mass of 190 kDa of S. mutans (PAc) is receiving attention as an anticaries vaccine. We have recently determined the complete nucleotide sequence of the gene for PAc. In this study, four peptides were synthesized on the basis of amino acid sequence of PAc. Among these peptides, PAc(301-319) corresponding to the alanine-rich repeating amino acid region was the most strongly bound by polyclonal murine anti-rPAc antibodies. The peptide partially inhibited the binding of polyclonal anti-rPAc antibodies to rPAc. The peptide induced the proliferation of T cells from BALB/c mice immunized with rPAc. Subcutaneous immunization with PAc(301-319) or rPAc emulsified in CFA/IFA induced high serum IgG responses to rPAc and PAc(301-319). In addition, serum IgG responses to a surface protein Ag with a molecular mass of 210 kDa of Streptococcus sobrinus were elicited in mice immunized by s.c. injection with PAc(301-319) or rPAc. Intranasal immunization with PAc(301-319) coupled to cholera toxin B subunit (CTB) or with rPAc and free CTB induced high serum IgG responses to rPAc. The immunization with PAc(301-319) coupled to CTB or rPAc and free CTB suppressed the colonization of murine teeth by S. mutans. These results suggest that intranasal immunization with the peptide or rPAc may be effective for the prevention of dental caries.

Animals↗