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PubMed1989

Classification and identification of the viridans streptococci.

This review traces the history of the human, nonhemolytic, or viridans, streptococci and describes improvements in their taxonomy wrought by study of their biochemical profiles and analysis of their nucleic acids. The goal was to define species on the basis of genetic relationships and to describe these species by their phenotypic characteristics so that they can be easily identified. This method has resulted in the division of some species. Streptococcus mutans has been divided into four species, two of which are common in humans. Three more mutans group species are indigenous to animals. Conversely, S. constellatus, S. intermedius, and "S. milleri" have been combined under S. anginosus. S. mitis (or "S. mitior") can be well-defined and includes S. sanguis II. There is genetic heterogeneity within S. sanguis, but the species is usually easy to identify. There is also some heterogeneity in S. bovis, but most human isolates are genetically related. Discussions of the taxonomy of these species are accompanied by descriptions of the characteristics by which these streptococci can be identified. Among these species are potential pathogens which should be suspected in cases of endocarditis and purulent infections of liver, brain, and other tissues.

Animals↗
PubMed1992

Use of a replica-plate assay for the rapid assessment of salivary protein-bacteria interactions.

A replica-plate assay was used to screen for the interaction of salivary molecules with dental plaque bacteria. Bacterial colonies cultured from supragingival plaque on sheep-blood (SB) agar were replica-plated onto nitrocellulose membranes overlaying SB or mitis-salivarius agar. Membranes with attached colonies were removed and incubated with 125I-amylase or 125I-proline-rich glycoprotein (PRG). Positive interactions were detected by autoradiography. Only strains of Streptococcus gordonii and Actinomyces viscosus bound amylase, and strains of A. viscosus bound PRG. The results suggest that amylase and PRG bind to selected species of aerobic dental plaque bacteria.

Actinomyces↗
PubMed1985

The surface free energy of oral streptococci after being coated with saliva and its relation to adhesion in the mouth.

Contact angle measurements on layers of bacteria were used to determine the bacterial surface free energy (gamma b) of a variety of oral streptococcal strains, both without and after being coated with human whole saliva. At least four isolates of each species, either freshly isolated or laboratory strains, were used. The species Streptococcus mutans, S. sanguis, and S. salivarius were homogeneous, having high surface free energies, and were not affected by saliva treatment (gamma b = 106 +/- 12 and 107 +/- 10 erg X cm-2 in the absence and presence of saliva coating, respectively; n = 20). S. mitis had a very low surface free energy (46 +/- 15; n = 5), which was significantly increased after salivary adsorption (71 +/- 14 erg X cm-2; p less than 0.002). The species S. milleri contained strains with both high and low gamma b. Calculation of the interfacial free energy of adhesion (delta F adh) for bacteria from a saliva suspension to solid surfaces with various arbitrary surface free energies (gamma s) showed that, theoretically, most strains will encounter thermodynamically favorable conditions for adhesion to surfaces with a gamma s above 62 erg X cm-2. However, S. mitis strains not coated with saliva would only be able to adhere to surfaces with gamma s lower than this value. Saliva-coating reverses the calculated relationship with gamma s for these strains. The results indicate that an enamel surface with a low gamma s value would be thermodynamically unfavorable for adhesion of most oral streptococci.

Adhesiveness↗
PubMed1990

Microbiology of root surface caries in humans.

Studies on the microbiology of root surface caries between 1970 and 1975 placed emphasis on Gram-positive pleomorphic filamentous rods, particularly Actinomyces viscosus and Actinomyces naeslundii. Both of these species had been shown to produce root surface caries in experimental animals. Since this time, studies have placed more emphasis on Streptococcus mutans, and S. mutans and Lactobacillus are significant in prediction of root surface caries risk in patients. Subsequent studies confirmed an association between S. mutans and 'soft' or 'initial' root lesions. Thus, it is important when determining the microflora of root surface lesions to make careful characterization of the state of the lesion. A second important aspect of the analysis of bacterial communities associated with root surface caries is better definition of the organisms. Most studies have concentrated on 'target organisms' S. mutans, S. sanguis, A. viscosus, A. naeslundii, Lactobacillus, and Veillonella. However, it has been known for 17 years that the Actinomyces associated with the lesions may be variants of A. viscosus and A. naeslundii. Such strains (intermediate strains) have been described in taxonomic studies of Actinomyces, yet little is known of the differences in physiology of these strains or their relationship to root surface caries. A similar situation exists with oral Streptococcus where new taxonomic divisions are being proposed. Recognition of the potential diversity within the 'target' genera of root surface caries could yield valuable data. Recent studies suggest that this is so, since samples from root surface lesions which contain S. mutans and Lactobacillus show a high isolation of S. mitis 1 and no isolations of A. naeslundii. Careful definition of the lesions of root surface caries and the flora will allow analysis to relate a specific bacterial community to the state fo the lesion and assist in monitoring the control of the lesion through fluoride and antibacterials.

Actinomyces↗
PubMed1985

Relationship of adhesion in vitro and cariogenicity of oral Streptococcus species in germ-free rats.

Thirty-two strains of Streptococcus spp., of known cariogenicity in the gnotobiotic WAG/RIJ rat, were tested for their in vitro adhesion properties. Computerized image analysis measured percentage coverage by, and clump size of, cells adhering to saliva-coated glass. An analysis of variance revealed significant differences for percentage coverage for the majority of species-pairs. There were fewer significant differences for mean clump size between species-pairs. Within the Strep. mutans group there was a highly-significant difference between Strep. mutans/Strep. cricetus (p less than 0.01) with respect to mean clump size. There was a significant correlation between cariogenicity and percentage coverage (p = 0.05) but not clump size (p = 0.359) for pooled strains of Strep. mitis and Strep. sanguis combined.

Adhesiveness↗
PubMed1980

Streptococcus mutans-like bacteria from human dental plaque in a Sri Lanka (Ceylon) population.

This paper reports on the presence of low numbers of Streptococcus mutans among the oral streptococci present in human dental plaque in a Sri Lanka (Ceylon) population, where the caries activity is low and a low sucrose intake is combined with the presence of heavy plaque deposits. Plaque samples of unknown age were collected from 10 individuals in a tea estate, and another 10 samples were collected from dental students 19 days following interruption of oral hygiene. Of 670 such strains of oral streptococci studied, none showed typical "frosted glass" colony morphology on Mitis Salivarius agar. However, when subjected to physiological tests 14 of them were classified as S. mutans.

Adult↗
PubMed1981

Examination of Streptococcus mutans for immunoglobulin G Fc reactivity.

Representative strains of oral streptococci were tested for Fc immunoglobulin G (IgG) reactivity by two different techniques, agglutination of rabbit-IgG sensitized sheep erythrocytes and uptake of human and rabbit 125I-radiolabeled IgG. None of the S. mutans serotypes a through e reacted with the Fc region of either human or rabbit IgG. Additionally, other streptococci such as S. sanguis, S. salivarius, S. faecalis, and S. mitis failed to show appreciable Fc reactivity as assayed by these techniques. The group A, C, and G streptococci, previously shown to possess Fc reactivity, proved to be reactive in these experiments, as did a protein A-containing strain of Staphylococcus aureus.

Hemagglutination Tests↗
PubMed1993

Species identification of oral viridans streptococci by restriction fragment polymorphism analysis of rRNA genes.

Oral streptococci formerly classified as Streptococcus sanguis have been divided into six genetic groups. Methods to identify those species by genotype are needed. This study compared restriction fragment polymorphisms of rRNA genes (ribotypes) for seven S. gordonii, three S. sanguis, four S. oralis, three S. mitis, one S. crista, and seven S. parasanguis strains classified in previous DNA hybridization studies, as well as one clinical isolate. DNA was digested with HindIII, PvuII, HindIII and PvuII combined, EcoRI, BamHI, AatII, AlwNI, and DraII. DNA fragments were hybridized with a digoxigenin-labeled cDNA probe obtained by reverse transcription of Escherichia coli 16S and 23S rRNA. S. oralis, S. mitis, and S. parasanguis all showed an isolated 2,290-bp band in AatII ribotypes that was absent from S. gordonii, S. sanguis, and S. crista. The last three groups showed species-specific bands with AatII and also with PvuII. S. oralis could be distinguished from S. mitis and S. parasanguis in AlwNI and DraII ribotypes. S. mitis and S. parasanguis could not be distinguished, since they shared multiple bands in PvuII, AlwNI, and EcoRI patterns. The clinical isolate in the panel was very similar to S. sanguis by all enzymes used. Our findings suggest that ribotyping may be useful for genotypic identification of oral viridans streptococci. Initial digests of clinical isolates might be made with AatII, followed by PvuII or AlwNI. Isolates then could be identified by comparing ribotype patterns with those of reference strains. This approach could facilitate clinical studies of these newly defined species.

Bacterial Typing Techniques↗
PubMed1991

Effect of immune bovine milk on Streptococcus mutans in human dental plaque.

The use of a mouthrinse of bovine milk containing antibodies to Streptococcus mutans resulted in an initial reduction in the numbers of recoverable Strep. mutans in a group of 9 individuals. Ten volunteers who used control bovine milk that contained no antibody activity to Strep. mutans had variable levels of plaque Strep. mutans. In addition, after culture on Mitis Salivarius and Gold's agar, the plaque Strep. mutans from subjects who used the immune bovine milk rinse formed smaller colonies than those from pre-treatment plaque and from all plaque samples of subjects who used the control rinse.

Adult↗
PubMed1985

Streptococcus mutans and Lactobacillus detection in the assessment of dental root surface caries risk.

Forty-five subjects contributing 150 root surfaces with gingival recession were sampled seven times over a 32-month period. We calculated isolation frequencies of lactobacilli on selective Rogosa SL agar and S. mutans in a sensitive enrichment broth and on mitis salivarius agar. Both S. mutans and lactobacilli were isolated more frequently from surfaces which became carious than from those remaining caries-free. Isolation frequencies were also higher for caries-free surfaces in caries-active subjects than for caries-free surfaces in caries-inactive subjects. The presence or absence of S. mutans and lactobacilli in samples taken at baseline could discriminate between subjects who were to be root-caries-active and those who were to remain root-caries-inactive during the subsequent observation period. Moreover, if both bacteria were detected or only S. mutans was detected on a root surface at its entry into the study, that surface had a greater risk for developing a root lesion. However, the tests could not predict which root surfaces within the mouths of caries-active subjects were to become carious. Analysis of the data suggests that simple microbiological detection tests may be useful in identifying patients at high risk of root caries.

Aged↗
PubMed1977

Comparative recovery of Streptococcus mutans on ten isolation media.

The ability of Streptococcus mutans (Bratthall serotypes a through e) to grow on 10 isolation media was examined. The number and morphology of the colonies were observed to vary on different media. The use of blood-sucrose media consistently produced the highest recoveries. Mitis salivarius agar (MS) and higher recovery values than modified medium 10 (MM10SB), Trypticase-yeast extract-cystine medium (TYC), or MS with 1% tellurite (MST). MST with 40% sucrose (MS40S), MST with 20% sucrose and 0.2 U of bacitracin per ml (MSB), and Carlsson medium with 1% sulfasoxazole (MC), media formulated for the selection of S. mutans, were the most inhibitory for all serotypes. The morphology of several S. mutans strains was atypical on MC and MS40S, making positive identification difficult. Absence of growth of serotype a strains on MSB and serotype d strains on MC were the two major differences observed among the serotypes. Results are discussed in terms of the difficulties in making quantitative determinations from cultural data.

Culture Media↗
PubMed1991

Relatedness between Streptococcus pneumoniae and viridans streptococci: transfer of penicillin resistance determinants and immunological similarities of penicillin-binding proteins.

The occurrence of highly variable penicillin-binding proteins (PBPs) in penicillin-resistant Streptococcus pneumoniae suggested that transfer of homologous genes from related species may be involved in resistance development. Antiserum and monoclonal antibodies raised against PBPs 1a and 2b from the susceptible S. pneumoniae R6 strain were used to identify related PBPs in 41 S. mitis, S. sanguis I and S. sanguis II strains mostly isolated in South Africa with MIC values ranging from less than 0.15 to 16 mg/ml. Furthermore, the possibility of genetic exchange was examined with 30 penicillin-resistant strains of this collection (MIC greater than 0.06 mg/ml) as donors using S. pneumoniae R6 as recipient in transformation experiments. The majority of S. mitis and S. sanguis II strains but none of the S. sanguis I strains could transform penicillin resistance genes into S. pneumoniae R6. All positive donor strains and all susceptible isolates of S. mitis and S. sanguis II strains contained PBPs which cross-reacted with the anti-PBP 1a and/or anti-PBP 2b antibodies. On the other hand, only five of the 14 S. sanguis I strains contained a PBP that reacted with one of the antibodies. This strongly suggested the presence of genes homologous to the pneumococcal PBP 1a and 2b genes in viridans streptococci, and documents that penicillin resistance determinants can be transformed from viridans streptococci into the pneumococcus.

Bacterial Proteins↗
PubMed1999

Spondylodiscitis caused by viridans streptococci: three cases and a review of the literature.

Three cases of spondylodiscitis caused by viridans streptococci were observed within the course of 1 month. Although streptococci have been reported as the third most frequent cause of spondylodiscitis after staphylococci and gram-negative bacteria, alpha-haemolytic streptococci are rarely seen. The three patients presented with symptoms of low back pain; they felt well and did not have a fever or chills. Laboratory examinations revealed inflammation. Further examinations such as scintigraphy, computed tomography or magnetic resonance imaging were done. Bacteriological diagnosis was established by blood cultures in two cases and by needle biopsy of the disco-vertebral space in one. In one patient endocarditis was also documented. Because the prevalence of endocarditis was found to be higher in our cases of spondylodiscitis due to Streptococcus viridans than for other bacteria, the exclusion of this diagnosis must be pursued aggressively. These observations lead us to question if the spectrum of bacteria causing spondylodiscitis is undergoing a change. an aetiological agent could be isolated in 1168 patients (85.4%): in 48% a staphylococcus, in 28% a gram-negative bacterium and in only 10% a streptococcus. There were two cases of viridans streptococci (0.2%). These two cases together with other single case reports [14-22] account for 15 cases of spondylodiscitis due to alpha-haemolytic streptococci. Differentiation of the organisms to the species level was accomplished in six cases: S. mitis (3), S. sanguis (2) and S. anginosus (1). Although a multitude of organisms, bacterial as well as fungal, causing spondylodiscitis has been reported in recent years, almost all were single cases [23-42]. The unusual observation of three cases of spondylodiscitis due to alpha-haemolytic streptococci within 1 month prompted us to review the clinical and laboratory findings and to compare these cases with those caused by Staphylococcus aureus.

Adult↗
PubMed1989

Streptococcus mutans, not detected?

The growth of Streptococcus mutans was followed for three years in 24 healthy 12-17 year-old children, who were selected for the study on the basis of undetectable levels of salivary S. mutans. The saliva samples were cultured by a dip-slide method based on mitis-salivarius agar supplemented with sucrose and bacitracin. At the final occasion, additional examination of plaque and saliva of 10 children using TSY20B agar was performed. During the 3-year study period, S. mutans was found in saliva samples from 15 children on one or more of the 4 test occasions, suggesting that most 'S. mutans negative individuals' were those in whom S. mutans could not be temporarily detected. The additional examination of plaque did not increase the number of 'S. mutans-positive individuals'.

Adolescent↗
PubMed1981

Effect of bacterial aggregation on the adherence of oral streptococci to hydroxyapatite.

Several in vitro assay systems to measure the adherence of human dental plaque bacteria to solid surfaces such as teeth, glass, and hydroxyapatite have been published. In many studies a variety of macromolecular solutes have been used to study the adherence process. Often these solutes are able to aggregate the test bacterial and thus may alter the outcome of adherence experiments. In this study, the effects of the aggregation of Streptococcus sanguis on adherence to spheroidal hydroxyapatite is described. Adherence of preformed aggregates and of bacteria which were aggregating during the adherence reaction was examined. Bacteria were aggregated with whole saliva, concanavalin A, and wheat germ lectin. Further effects of the coaggregation of S. mitis and Actinomyces viscosus to saliva-coated spheroidal hydroxyapatite are presented. These studies suggest that formation of large aggregates resulted in a decrease in the numbers of organisms which adhered. In contrast, the formation of small aggregates actually increased the numbers of bacteria that adhered. All increases in adherent bacteria occurred at low concentrations of aggregating substance in which visible bacterial aggregation was not evident. The data indicate that adequate dose-response experiments must be performed to ensure that solutes used as probes to study adherence mechanisms do not affect the adherence simply as a result of aggregation of the test microorganisms.

Actinomyces↗
PubMed2006

Comparison of culture media and chairside assays for enumerating mutans streptococci.

AIM: This study compared several traditional culture-based media and chairside cultural assays for ability to recover mutans streptococci (MS) from pure cultures and from saliva samples. METHODS AND RESULTS: When pure cultures were used with traditional culture-based media, mitis-salivarius bacitracin (MSB) agar demonstrated less support for bacterial recovery than trypticase-yeast extract-cysteine sucrose-bacitracin (TYCSB) agar and the modified medium of Ritz (HLR-S). One species of MS, Streptococcus ferus (c), was not recovered on MSB medium. Chairside cultural tests displayed considerable disparity between tests in recovering bacteria from pure cultures. On the glass adherence assay (Mucount), S. ferus was not detected and Streptococcus criceti was not detected on the dipslide assay (Cariescreen SM) or on the plastic adherence assay (Dentocult SM Strip mutans). The frequency of isolation of pure strains of bacteria other than MS was common. From saliva samples, the frequency of isolation of MS on HLR-S and TYCSB media and the glass adherence assay was 91-97%. The frequency of isolation on MSB medium and on the dip-slide and plastic adherence assays was significantly decreased (37, 47 and 69%, respectively). Recovery scores varied considerably among the culture methods studied and tended to be highest on the HLR-S medium and on the glass adherence assay. CONCLUSIONS: Growth and recovery profiles of pure bacterial cultures and of saliva samples for the MS varied according to different media. SIGNIFICANCE AND IMPACT OF THE STUDY: Caution should be exercised in comparing results between studies that employ different cultural methods for MS enumeration.

Adolescent↗
PubMed1997

Natural competence in the genus Streptococcus: evidence that streptococci can change pherotype by interspecies recombinational exchanges.

To map the incidence of natural competence in the genus Streptococcus, we used PCR to screen a number of streptococcal strains for the presence of the recently identified competence regulation operon, containing the comC, -D, and -E genes. This approach established that the operon is present in strains belonging to the S. mitis and S. anginosus groups, but it was not detected in the other strains examined. Competence is induced in S. pneumoniae and S. gordonii by strain-specific peptide pheromones, competence-stimulating peptides (CSPs). With its unique primary structure, each CSP represents a separate pheromone type (pherotype), which is recognized by the signalling domain of the downstream histidine kinase, ComD. Thus, all bacteria induced to competence by a particular CSP belong to the same pherotype. In this study, we identified a number of new pherotypes by sequencing the genes encoding the CSP and its receptor from different streptococcal species. We found that in several cases, these genes have a mosaic structure which must have arisen as the result of recombination between two distinct allelic variants. The observed mosaic blocks encompass the region encoding the CSP and the CSP-binding domain of the histidine kinase. Consequently, the recombination events have led to switches in pherotype for the strains involved. This suggests a novel mechanism for the adaptation of naturally competent streptococci to new environmental conditions.

Amino Acid Sequence↗