J. van Houte

Adherence as a determinant of the presence of Streptococcus salivarius and Streptococcus sanguis on the human tooth surface

The proportions of Streptococcus salivarius, and other zooglea-producing streptococci of the total facultative streptococci on Mitis-salivarius agar were determined in samples obtained from the lingual surfaces of both central upper incisors of nine subjects within 30–120 min after thorough prophylaxis. The percentages of Strep. salivarius on the tooth surfaces were much lower than those in samples of saliva or of the tongue tip obtained simultaneously. On the other hand, the percentages of other zooglea-forming streptococci, most of which were considered to be Streptococcus sanguis, were very high on the tooth surfaces but much lower in the saliva and tongue tip samples. The observed differences in proportions of these organisms in the initial phase of plaque formation are considered to be due to differences in ability to adhere to the tooth surface rather than in ability to grow on the tooth surface. These observations seem to provide an explanation for the relative proportions of Strep. salivarius and Strep. sanguis in mature dental plaque.

The prevalence of enterococci in the human mouth and their pathogenicity in animal models

Abstract Enterococci were detected in 60–75 per cent of subjects in three populations consisting of 20–40-yr-old laboratory personnel, 10–14-yr-old school children with high caries activity and patients with infected root canals. The dorsum of the tongue, the vestibular mucosa, dental plaque and saliva from all individuals were cultured. In addition, carious lesions in school children and root canals in endodontic patients were sampled. No preferred colonization among these sites by enterococci was detected. Streptococcus faecalis was the most frequently isolated species from the human mouth. One of the four isolates of enterococci tested in germfree rats was cariogenic. Enterococcus strains could not be tested for odontopathic activity in conventional non-germfree rats due to poor implantation and the presence of an indigenous enterococcus flora.

Adherence as an ecological determinant for streptococci in the human mouth

Abstract The adherence of Streptococcus species to dental plaque and oral epithelial surfaces was studied in vivo by introducing mixtures of streptomycin-labelled strains into the mouths of volunteers. The proportions of labelled Strep. sanguis recovered from the cleaned teeth or preformed plaques were much higher than those of Strep. salivarius after a 45 and 30 min experimental period respectively. The adherent behaviour of in vivo-grown labelled organisms for cleaned teeth was similar to that of the same species present naturally in the mouth. The data provide additional support for the concept that the low proportion of Strep. salivarius in dental plaque is due to its inability to adhere to the tooth surface or developing plaque. The proportions of labelled Strep. salivarius were higher than those of Strep. sanguis on the dorsum of the tongue but lower on the vestibular mucosa. The proportions of labelled Strep. mutans in both sites were low as compared to those of Strep. salivarius and Strep. sanguis. The relative adherence of these Streptococcus species to the tongue and vestibular mucosa correlates with their proportions found naturally in these sites. Thus, adherence seems to be an important determinant for the colonization of Strep. salivarius, Strep. sanguis and Strep. mutans on the tongue and vestibular mucosa as well as on teeth.

Studies of the predominant cultivable microbiota of dental plaque

Abstract All of the cultivable bacteria present in high dilutions of dental plaque have been isolated, partially characterized, and their relative proportions determined. The predominant cultivable microbiota of dental plaque was found to be comprised of the following groups of organisms: facultative streptococci, 27%; facultative diphtheroids, 23%; anaerobic diphtheroids, 18%; peptostreptococci, 13%; Veillonella , 6%; Bacteroides , 4%; fusobacteria, 4%; Neisseria , 3%; and vibrios, 2%. Total microscopic counts of dental plaque averaged 2·5 × 10 11 bacteria/g. Total cultivable counts performed anaerobically and aerobically averaged 4·6 and 2·5 × 10 10 /g respectively.

Relationship of Streptococcus mutans and lactobacilli to incipient smooth surface dental caries in man

Small samples of plaque were obtained from a number of incipient (white spot) caries lesions on buccal tooth surfaces or cavitated caries lesions on buccal and approximal surfaces. The clinically-sound tooth surface surrounding each lesion was similarly sampled. The proportions of Streptococcus mutans in samples from carious areas were significantly higher than those from the adjacent sound surface areas. Lactobacilli were not detected in samples from white spots and were recovered from only a few samples from the surrounding sound tooth surface. S. mutans preferentially colonized the gingival area of buccal tooth surfaces. The heterogeneity of dental plaque with respect to the concentrations of S. mutans was striking; 100-fold differences in concentration between samples taken from a single lesion were frequent. The recovery of S. mutans from plaque cultured on mitis-salivarius agar, supplemented with 15 per cent sucrose and 0.2 units per ml of bacitracin (MSB agar), which is selective for this organism, was generally lower than with mitis-salivarius agar without tellurite. Its recovery on MSB agar with and without tellurite was similar.

In-vitro inhibition of glucosyltransferase from the dental plaque bacterium Streptococcus mutans by common beverages and food extracts

Some fruit juices and beverages inhibit the glucosyltransferases of Streptococcus mutans. Inhibition by cocoa, coffee and tea was due partly to gelatin-precipitable tannins and partly to components that exhibited properties of monomeric polyphenols. Charcoal treatment removed all inhibitory activity. Catechin, a known constituent of these beverages, was an effective inhibitor of the enzymes. The effects of the fruit juices were attributable mainly to the inhibition of the glucosyltransferases by the endogenous fructose and glucose. The findings show that naturally-occurring constituents of foods can inhibit extracellular polysaccharide formation from sucrose. Such constituents may play a role in regulating dental plaque formation in vivo and, thereby, may have long-term effects on the development of dental caries.

Studies of the cultivable flora of normal human feces

Highly diluted feces, obtained from healthy adult individuals, was plated on blood-agar plates which were incubated both aerobically and anaerobically. From the anaerobic plates containing 30 to 60 colonies, every colony was subcultured. Nearly all isolates were obtained in pure culture and partially characterized. It was found thatBacteroides species were the most predominant organisms, being present in numbers approximating 1010 per gram wet weight. Selected bacteria present in lower numbers were determined by plating appropriate dilutions of feces on selective media. It was found that coliforms, streptococci and lactobacilli were regularly present in concentrations of 106 − 108 organisms per gram wet weight material, whileVeillonella, Streptococcus salivarius, Bacteroides melaninogenicus and staphylococci were present in lower numbers. Fusobacteria were only found in one sample, whileNeisseria were not detected in any of the samples. Wet mounts of fecal material, inspected by darkfield microscopy, did not reveal the presence of spirochetes.Anaerobes outnumbered facultative bacteria by a factor of 40, indicating that the human adult fecal flora is predominantly anaerobic. Total microscopic counts indicate that bacteria comprise approximately 30% of the mass of human feces.

Development of a New Intraoral Demineralization Test

Blocks of bovine enamel covered with a layer of Streptococcus mutans cells were mounted in specially-designed holders in a prosthesis and carried intraorally for 2 h. Measurements o

Cell Wall Thickening and Intracellular Polysaccharide in Microorganisms of the Dental Plaque

The morphology of human dental plaque has been studied with the electron microscope. In the inner part of the plaque, especially in the region adjacent to the tooth surface, many microorganisms exhibit unusually thick cell walls and contain large amounts of intracellular polysaccharide. The magnitude of both phenomena diminishes towards the saliva-plaque interface. Both cell wall thickening and intracellular polysaccharide storage are considered to be manifestations of a so called ‘unbalanced growth’ situation, suggesting a low or negligible rate of cell multiplication.

Relationship of levels of the bacterium Streptococcus mutans in saliva of children and their parents

Abstract 85 Children diagnosed as caries free (CF), and 67 caries-positive (CP) children, aged 5–8 yr, were studied for the presence of Streptococcus mutans in saliva. All mothers and most fathers of 50 of the CF children and about 2 3 of the mothers of the CP children were studied similarly. The detection frequency of Strep. mutans in the CF children (59 per cent) was significantly lower than that in the CP children (96 per cent); its mean and median levels were also significantly lower (about 10-fold) in CF children. The detection frequency of Strep. mutans in the mothers of the CF children (62 per cent) was also significantly lower than that in either the fathers of these children (92 per cent) or the mothers of the CP children (100 per cent); this was so also for median salivary Strep. mutans levels. A tendency towards a positive association was found between the Strep. mutans levels of the CP children and their mothers but not between the CF children and either their mothers or fathers. The findings support a role of Strep. mutans in the aetiology of dental caries and suggest a familial tendency with respect to oral Strep. mutans infection.