Emended descriptions and recognition of Streptococcus constellatus, Streptococcus intermedius, and Streptococcus anginosus as distinct species

Strains currently classified as Streptococcus anginosus include strains previously identified as Streptococcus constellatus (Prevot 1924) Holdeman and Moore 1974, Streptococcus intermedius (Prevot 1925), and "Streptococcus milleri" (Guthof 1956) because these specific epithets were argued to be later synonyms of Streptococcus anginosus (Andrewes and Horder 1906) Smith and Sherman 1938 by Coykendall et al. (Int. J. Syst. Bacteriol. 37:222-228, 1987). However, recent data from DNA-DNA hybridization experiments, whole-cell-derived polypeptide patterns determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and data from phenotypic testing have demonstrated that Streptococcus anginosus strains represent three readily identifiable taxa to which the previously assigned type strains of Streptococcus constellatus (strain NCDO 2226 [= ATCC 27823], Streptococcus intermedius (strain NCDO 2227 [= ATCC 27335], and Streptococcus anginosus (strain NCTC 10713 [= ATCC 33397] have been shown to belong. Therefore, we propose recognition of Streptococcus constellatus (emend.) (type strain NCDO 2226 [= ATCC 27823]), Streptococcus intermedius (emend.) (type strain NCDO 2227 [= ATCC 27335]), and Streptococcus anginosus (emend.) (type strain NCTC 10713 [= ATCC 33397]) as distinct species and propose an emended description of each of these taxa.

Fluorometric determination of bacterial protease activity using fluorescein isothiocyanate-labeled proteins as substrates

Intact fluorescein isothiocyanate-labeled proteins have relatively low background fluorescence at excitation and emission wavelengths of 495 and 525 nm, respectively. Degradation of these substrates leads to exposure of covalently linked fluorescein isothiocyanate molecules and to a concomitant increase in relative fluorescence at these wavelengths. The increase in relative fluorescence is proportional to the degree of protein degradation. This phenomenon provides the basis for a sensitive assay for bacterial protease activity. There is no requirement for the removal of undegraded substrate from the assay mixture prior to the measurement of fluorescence. Assays can be performed in 96-well microtiter trays, enabling a large number of samples and their respective controls to be processed simultaneously and repeated determinations of fluorescence values may be made on the same assay.

Root caries in older people attending a general dental practice in East Sussex

With increasing numbers of older people retaining their natural dentitions, dentists are becoming increasingly aware of the problem of dental caries occurring on exposed root surfaces--root caries. This study reports the prevalence of root caries in a selected older population, living in the community and attending a general dental practice in Bexhill, East Sussex. A total of 146 non-institutionalised people, aged at least 55 years with at least 12 teeth, were examined. Most of the subjects (88.4%) had evidence of root caries, males and denture wearers having more lesions than females and non-denture wearers, respectively. Active coronal caries was present in only 11.6% of the subjects, whereas active (soft or leathery) root caries lesions were present in 31.5% of the subjects. The teeth and surfaces most commonly affected by root caries were found to be similar to those seen in previous epidemiological surveys. The majority of active root caries lesions were within 1 mm of the gingival margin, while inactive lesions tended to be greater than or equal to 1 mm from the gingival margin. Colour of root caries lesions was not diagnostic of caries activity. A more detailed method of recording root caries lesions is also described.

Phenotypic differentiation of Streptococcus intermedius, Streptococcus constellatus, and Streptococcus anginosus strains within the "Streptococcus milleri group"

A biochemical scheme was developed by which strains of Streptococcus constellatus, Streptococcus intermedius, and Streptococcus anginosus can reliably be distinguished from within the "Streptococcus milleri group." Strains identified as S. intermedius were differentiated by the ability to produce detectable levels of alpha-glucosidase, beta-galactosidase, beta-D-fucosidase, beta-N-acetylgalactosaminidase, beta-N-acetylglucosaminidase, and sialidase with 4-methylumbelliferyl-linked fluorogenic substrates in microdilution trays after 3 h of incubation at 37 degrees C, together with the production of hyaluronidase. Strains of S. constellatus and S. anginosus were differentiated by the production of alpha-glucosidase and hyaluronidase by the former and the production of beta-glucosidase by the latter. The majority of strains of the S. milleri group obtained from dental plaque were identified as S. intermedius, as were most strains isolated from abscesses of the brain and liver. Strains of S. constellatus and S. anginosus were from a wider variety of infections, both oral and nonoral, than were strains of S. intermedius, with the majority of strains from urogenital infections being identified as S. anginosus.

Sialidase activity of the "Streptococcus milleri group" and other viridans group streptococci

Viridans group streptococci were examined for the production of sialidase (neuraminidase) activity, using the fluorescent substrate 4-methylumbelliferyl-alpha-D-N-acetylneuraminic acid in a simple and rapid (15-min) assay. Sialidase was produced by all strains of Streptococcus oralis and S. intermedius and by a majority of S. mitis strains. S. mutans, S. sobrinus, S. gordonii, S. sanguis, S. vestibularis, S. salivarius, S. anginosus, S. constellatus, "S. parasanguis," and the "tufted fibril group" were uniformly negative. Sialidase production may be a useful characteristic to assist in the identification of viridans group streptococci.

Proteolytic activity of oral streptococci

Streptococcus mutans and Streptococcus sobrinus were the least proteolytic of 8 species of oral streptococci while Streptococcus oralis and Streptococcus sanguis were the most proteolytic. Degradation of FITC-BSA was significantly correlated with the hydrolysis of synthetic endopeptidase substrates. As S. oralis strains proliferate in dental plaque in the absence of dietary food their success, in vivo, might be due partially to their greater proteolytic activity compared to other oral streptococci.

Protease activity in gingival crevicular fluid from discrete periodontal sites in humans with periodontitis or gingivitis

Sensitive fluorogenic assays were used to compare the protease activities of fluid collected from eight such sites in each of 21 adult patients with gingivitis and 22 with periodontitis. The degradation of N-carbobenzoxy-gly-gly-arginine-AMC, L-arginine-AMC, glyproline-AMC, L-leucine-AMC, N-alpha-benzoyl-L-arginine-AMC, N-[p-toluenesulphonyl]-gly-pro-arginine-AMC, N-tert-butoxycarbonyl-leu-ser-thr-arginine-AMC, N-tert-butoxycarbonyl-ileu-glut-gly-arginine-AMC and N-tert-butoxycarbonyl-val-leu-lysine-AMC was significantly greater by fluid from the periodontitis group. The specific rates of degradation of L-arginine-AMC, gly-proline-AMC, N-alpha-benzoyl-L-arginine-AMC and N-[p-toluene-sulphonyl]gly-pro-arginine-AMC were significantly greater in that group, indicating that the composition of their gingival crevicular fluid was different from that of the gingivitis group. Discriminant analysis of the substrate hydrolysis data alone correctly identified 77.6% of sites with sensitivity and specificity values of 73.3 and 82.1%, respectively. The predictive value of these assays requires further investigation, but it is possible that they will prove useful for monitoring the success of periodontal treatment.

Associations between salivary levels of mutans streptococci, lactobacilli, yeasts and black-pigmented Bacteroides spp. and dental variables in elderly dental patients

Multivariate step-wise regression analyses demonstrated that in a population of 146 elderly dental patients (mean age 69.8 yr) the salivary level of mutans streptococci was unrelated to the root DFS score, unlike the levels of lactobacilli and yeasts. Mutans streptococci were related to the wearing of partial dentures and the number of snacks eaten per day, while salivary lactobacillus levels were also related to the number of snacks eaten per day and to denture wearing, and negatively related to saliva buffering. Salivary yeast levels were also related to the wearing of partial dentures and the number of snacks eaten per day, and negatively related to salivary neuraminidase activity. The R2 values ranged from 0.21 to 0.28. Salivary level of black-pigmented Bacteroides spp. were related to maximum CPITN score, mean bleeding index and salivary trypsin-like activity (R2 was 0.08).

Inhibition of protease activities of periodontopathic bacteria by extracts of plants used in Kenya as chewing sticks (mswaki)

Extracts from five plants used as chewing sticks, and tannic acid, gallic acid and methyl ester of gallic acid, were tested for their ability to inhibit proteolytic activities of three strains of Bacteroides gingivalis, three strains of Bacteroides intermedius and two strains of Treponema denticola. Aqueous extract from the plants Rhus natalensis and Euclea divinorum were the most inhibitory of those tested, inhibiting by 50% the proteolytic activity of the test organisms, at concentrations of up to 200 micrograms/ml. Tannic and gallic acids had similar effects at concentrations of less than 10 micrograms/ml, while the methyl ester of gallic acid was less inhibitory. These findings suggest that extracts from plants used as chewing sticks may possess enough inhibitory components to interfere with the virulence and growth of periodontopathic bacteria in vivo, provided they are able to gain access to the subgingival sites such bacteria preferentially inhabit.

Associations between salivary levels of Streptococcus mutans, Streptococcus sobrinus, lactobacilli, and caries experience in Kenyan adolescents

Salivary levels of mutans streptococci (S. mutans and S. sobrinus) and lactobacilli were determined in a random sample of rural Kenyans between 15 and 19 years of age (n = 149). It is possible for the natural history of dental caries in this population to be studied since it is characterized by a limited access to conventional dental treatment. Using a short set of biochemical tests, we identified from seven to ten presumptive mutans streptococcus colonies--cultured from the saliva of each individual--to differentiate between S. mutans and S. sobrinus. No colonies resembling S. rattus (S. mutans serotype b) were isolated. Lactobacilli were identified as Gram-positive, catalase-negative rods. The mean D1-4MFS and D3-4MFS were 7.03 +/- 6.43 and 1.46 +/- 3.44, respectively. The mean mutans streptococcus and lactobacillus levels were 8.7 x 10(4) and 6.7 x 10(4), respectively. The salivary mutans streptococcus and lactobacillus levels were significantly correlated (p less than 0.01). Of the subjects, 64% harbored only S. mutans, 4% only S. sobrinus, 30% both species, and 2% neither. Lactobacilli were ubiquitous. The caries experience of the group was significantly (p less than 0.001) correlated with both the total salivary level of mutans streptococci and the salivary S. mutans levels, but not with the salivary S. sobrinus level.

Intra-oral colonization of macaque monkeys by Actinobacillus actinomycetemcomitans

Actinobacillus actinomycetemcomitans was acquired by captive Macaca fascicularis 3 to 6 months after birth, and all monkeys aged over 6 months harbored detectable levels. This microorganism was most frequently isolated from the gingival plaque of the incisor (and other) teeth compared with other oral sites. Strains were leukotoxic by bioassay and Western blot analysis. Antibodies in macaque serum contained neutralized the leukotoxin of a human A. actinomycetemcomitans strain. High titres of maternal neutralizing anti-leukotoxin antibodies were detected in neonates; the titre then fell rapidly so that by 6 months the antibody titer was zero. Antileukotoxin antibody production was detected after 6 months of age, rapidly reaching a high level within 2 years after birth. The presence of leukotoxic strains of A. actinomycetemcomitans in the gingival region did not appear to be correlated with an increase in susceptibility to periodontal disease.

Trypsin-like, chymotrypsin-like and glycylprolyl dipeptidase activities in gingival crevicular fluid from human periodontal sites with gingivitis

These activities were measured simultaneously, using synthetic fluorescent protease substrates, in gingival crevicular fluid collected at 6 pre-determined sites from 10 individuals with mild to moderate gingivitis. The three enzyme activities were detected in 85, 18 and 93% of the sites, respectively. The volume of fluid collected from discrete sites was significantly correlated with the total amount of substrate hydrolysed, but not with the specific rate of substrate hydrolysis. Log10 (total trypsin-like activity) was significantly correlated with the Gingival Index, Plaque Index and probing depth (r = 0.319, 0.423 and 0.336), while total glycylprolyl dipeptidase activity was significantly correlated with probing depth (r = 0.381). These findings add to knowledge of the biochemistry of gingival crevicular fluid, but the usefulness of such assays for diagnostic or monitoring purposes in periodontal diseases needs to be determined.

Streptococcus mutans levels in saliva and distribution of serotypes among 9-year-old Icelandic children

Streptococcus mutans levels in saliva were determined in 9-yr-old children from five towns in Iceland. In four towns the mean counts were greater than 10(5)/ml. Serotype c was predominant but types e and d/g were also found. The proportion of children harbouring serotype d/g alone or in combination with other serotypes was higher than that reported in most other studies.

Proteolytic activities in the supragingival plaque of monkeys (Macaca fascicularis)

Thirteen peptidase substrates were hydrolysed by this plaque. After fasting the monkeys for 24 h, the rates of hydrolysis of N-leucyl-, N-alanyl-, N-isoleucyl- and N-tyrosyl-2-naphthylamines, glycyl-L-proline 4-nitroanilide, N alpha-benzoyl-DL-arginine-2-naphthylamine and L-leucyglycine were significantly increased. Changes in these peptidase activities may serve to enhance the mobilization of amino acids and peptides, and they may explain why the growth rates of dental-plaque bacteria in vivo are generally unaffected by the availability of the host's diet.

The effects of the availability of diet on the levels of exoglycosidases in the supragingival plaque of macaque monkeys

Supragingival plaque from macaque monkeys was assayed for 13 exoglycosidase enzymes, with appropriate p-nitrophenylglycosides and N-acetylneuramin-lactose used as substrates. Protein in each plaque sample was quantitated with a Coomassie Brilliant Blue dye binding assay, and the specific activity of each enzyme was calculated. In monkeys fed a starch-based diet, fasting resulted in significant increases in the levels of alpha-L-fucosidase, beta-N-acetyl-D-glucosaminidase, beta-N-acetyl-D-galactosaminidase, and neuraminidase. Such changes are consistent with the hypothesis that plaque bacteria degrade salivary glycoproteins for their growth and maintenance in both the presence and especially the absence of dietary food. In contrast, fasting monkeys previously fed a sucrose-rich diet showed no significant alterations in the specific activities of those enzymes whose levels were increased in the starch-based diet group. It is considered likely that, under the conditions prevailing when the sucrose-rich diet is fed, the effective and maximal utilization of sucrose by plaque bacteria necessitates the increased mobilization of nitrogen sources, including the amino sugars of glycoproteins.

The growth of bacteria and the production of exoglycosidic enzymes in the dental plaque of macaque monkeys

The rate of growth of the predominant bacterial strains of plaque from the developmental grooves of first deciduous molar teeth was determined. Median doubling times were 3.32, 3.45, 2.88 and 4.54 h for streptococci, lactobacilli, actinomyces and Neisseria mucosa respectively. Withdrawal of dietary food did not greatly influence the number of bacteria found in the grooves 18 h after they had been cleaned when compared to the number in fed monkeys; exceptions were significant increases in Streptococcus mitior and N. mucosa. Addition of 0.5 per cent (w/v) glucose to the drinking water of fasted monkeys also did not influence the size of this bacterial population 18 h after cleaning, so bacteria growing in cleaned grooves must gain a major part of their nutritional needs from their immediate environment, most likely salivary constituents. The ability of oral bacteria to use the oligosaccharide side-chains of salivary glycoproteins was then explored. Exoglycosidases for the preferred anomeric linkages of the principal monosaccharide units of salivary glycoproteins were produced both by oral bacteria in vitro and by dental plaque in vivo. Thus plaque flora has the potential to degrade glycoproteins and this may explain how bacteria in the grooves grow in the absence of dietary food.

The influence of diet on the growth of streptococcal bacteria on the molar teeth of monkeys (Macaca fascicularis)

The rates of regrowth of bacteria in developmental grooves on these teeth were determined. Plaque was removed from palatal grooves up to 96 h after cleaning and the number of bacteria and of individual streptococcal species were determined; Streptococcus sanguis, Streptococcus mutans and Streptococcus mitior were the major ones. In monkeys fed one of three different diets, the numbers of each species reached stable levels 18-24 h after tooth cleaning. The median doubling times of the streptococcal population were 4.69, 3.82 and 4.25 h for two maintenance diets and a sucrose diet, respectively. The median doubling times of individual species ranged from 2.01 to 4.38 h and appeared to be independent of the composition of the various diets. There was no difference in the number of bacteria in 18 h-old plaque from discrete sites in fed or fasted monkeys, nor in the numbers of streptococci, except that the size of the Strep. mitior population increased significantly with fasting. Thus host-derived substrates, possibly salivary components, may be used by plaque bacteria and support their on growth in developmental grooves in the absence of food.

The relationship between the number of the bacterium Streptococcus mutans at discrete sites on the dentition of macaque monkeys (Macaca fascicularis) and the subsequent development of dental caries

Sixteen consecutively-born monkeys were used in a longitudinal study to determine the changes occurring in the total number of bacteria in the palatal grooves of the upper left first deciduous molar teeth, following the introduction of a sucrose-based diet. The total number of bacteria recovered from the grooves increased significantly following the diet change. Twenty-nine days after the diet change, the number of Streptococcus mutans had increased from a median value of less than 10(2) to approx. 10(7) per groove, and the number of Streptococcus sanguis decreased. These changes in the number of Strep. mutans occurred prior to the detection of dental caries. Grooves that became carious harboured significantly more bacteria and more Strep. mutans than did grooves remaining caries-free six months after the diet change.

Establishment and distribution of the bacteria Actinomyces viscosus and Actinomyces naeslundii in the mouths of monkeys (Macaca fascicularis)

The colonization of the mouth by the two Actinomyces species, postulated to be members of a basic plaque flora, was studied in 27 consecutively-born neonatal monkeys. Bacteria adherent to the tongue and cheek surfaces were sampled from each monkey soon after birth (mean age = 3.2 days). The tongue and cheek surfaces and the labial surfaces of the incisor teeth were sampled at 4, 8 and 12 weeks of age. From only one neonatal sample were Actinomyces species isolated. By 4 weeks of age, the incisor teeth are partially erupted and, from teeth erupted more than 1 mm, A. naeslundii was frequently isolated and its proportion increased between 4 and 8 weeks on all surfaces sampled. At 4, 8 and 12 weeks, the proportion of A. naeslundii on the incisor teeth was greater than on the mucosal surfaces. The isolation rate of A. viscosus was low in these neonates, but it was isolated from each of 6 juvenile monkeys fed a starch diet. In the 6 juvenile monkeys, the proportion of A. viscosus decreased following the introduction of a sucrose-containing diet, whereas the proportion of A. naeslundii on the teeth increased. The early establishment of A. naeslundii and, to a lesser extent, A. viscosus in the dental plaque of neonatal monkeys fed exclusively by their mothers suggests that members of a basic plaque flora may be those bacteria establishing in the plaque during the period of breast-feeding.