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Biomedical subjects

D B Drucker

Publications and source records attributed to D B Drucker.

At least 91 records · Page 5Linked to original sources
PubMed1989

Comparative cariogenicity and dental plaque-forming ability in gnotobiotic rats of four species of mutans streptococci.

The four species, each represented by two strains, all produced high levels of fissure caries in the upper and lower jaws of gnotobiotic Fisher rats. Streptococcus rattus strains and Streptococcus mutans NCTC 10832 gave low levels of approximal caries, whereas Streptococcus cricetus, Streptococcus sobrinus and Strep. mutans NCTC 10449 gave high levels. The only strains to produce buccal surface lesions were Strep. sobrinus and Strep. cricetus. All strains were able to form dense plaque in the central fissure of the second molar. Strep. cricetus, Strep. rattus and Strep. sobrinus strains were capable of producing smooth-surface plaque. This difference in plaque-forming ability did not correlate precisely with differences in cariogenicity, and such differences occurred between strains of the same species.

Animals↗
PubMed1989

The nasopharyngeal bacterial flora in the sudden infant death syndrome.

The nasopharyngeal bacterial flora in babies who had died of the sudden infant death syndrome (SIDS) (n = 46) and in healthy infants aged 2 weeks to 6 months (n = 46) is described. Of those who had died, 41.3% carried Staphylococcus aureus (95% confidence limits: 27.3-55.3%) compared with 28.3% of healthy infants (95% confidence limits: 15.3-41.3%). The isolation rate of streptococci was 78.3% in cases (95% confidence limits: 66.4-90.2%) and 32.6% in healthy infants (95% confidence limits: 19.1-46.1%) (significant difference P less than 0.0001). Enterobacteria were isolated from 45.6% of cases (95% confidence limits: 31.2-60%) but only 2.2% of healthy infants (95% confidence limits 0-6.4%) (significant difference, P less than 0.0001). These results indicate a disordered nasopharyngeal flora in SIDS. They also provide baseline data for investigating the hypothesis that common bacterial toxins are involved in the pathogenesis of SIDS.

Bacteria↗
PubMed1989

Surface structures, co-aggregation and adherence phenomena of Streptococcus oralis and related species.

Seven strains of Streptococcus oralis were found to possess surface structures. Four strains possessed long fimbriae which ranged in length from 266-366 nm, while the remaining three strains possessed shorter peritrichously distributed fibrils which ranged in length from 80-197 nm. The fibrillar strains were morphologically similar to strains of Streptococcus sanguis I and II and Streptococcus mitis. No strain of S. oralis produced tufts of fibrils like certain strains of S. sanguis I. Strains of Streptococcus milleri produced peritrichously distributed fimbriae which were morphologically dissimilar to the fimbriae produced by S. oralis strains. S. oralis strains were moderately to highly hydrophobic, but hydrophobicity could not be related to adhesion parameters or type or length or density of surface structures. Furthermore, there appeared to be no correlation between type of surface structures and adhesion parameters. Two of the three fibrillar strains of S. oralis and the peritrichously fibrillar strains of S. sanguis, together with one strain of S. milleri, were able to co-aggregate with actinomycetes.

Actinomyces↗
PubMed1989

Genetic transformation in some cariogenic Streptococcus milleri.

Only one of six Streptococcus milleri strains, known to produce dental caries in gnotobiotic rats, was found to be spontaneously transformable. At optimal competence (after 60 min incubation in transformation medium) DNA uptake by this strain, CR 287, was rapid; maximum DNA was taken up by cells within 15 min of its addition to give a transformation frequency of 1 x 10(-2) transformants per colony-forming unit (cfu). With post-optimally competent cells, the rate of DNA uptake was markedly decreased, although a transformation frequency similar to that of optimally competent cells was obtained. For example, after 240 min incubation in transformation medium the cells required approximately 90 min to reach maximum DNA uptake and gave a transformation frequency of 6 x 10(-3) transformants per cfu. Cultures retained the ability to give their maximum transformation frequency for at least 4 h, but only if a DNA-cell contact time of 2 h was used. Strain CR 287 and S. milleri strain NCTC 10707, a transformable non-cariogenic strain, produced competence factor (CF). The CF of CR 287, but not that of NCTC 10707, induced high competence in the non-spontaneously transformable cariogenic S. milleri strain NCTC 11169. Like S. sanguis, S. milleri must therefore produce CFs of different constitutional types. The three transformable strains could be transformed by plasmid shuttle cloning vector pVA838 DNA.

Animals↗
PubMed1989

Gas liquid chromatography of amines produced by the Enterobacteriaceae.

1. Gas liquid chromatography (GLC) was used to test the production of amines by 85 strains of Enterobacteriaceae. 2. The strains tested produced cadaverine, beta-phenylethylamine, putrescine, iso-amylamine, 2-methylbutylamine and iso-butylamine. 3. Although the overlap in amine production between obviously different genera and species limits the general applicability of this methodology in clinical microbiology, the results obtained demonstrate the possibility of differentiating Proteus rettgeri from other Proteus species, Escherichia coli from Proteus species and Salmonella species from Shigella species on the basis of their amine composition. 4. In general, members of the Enterobacteriaceae family produce qualitatively similar amine profiles, though differing quantitatively in the amounts of individual amines produced. GLC proved to be useful for separating amines and for providing tentative peak identification.

Amines↗
PubMed1989

The improved recovery of Candida albicans from fluid culture media.

This study compares the mean generation time (MGT) and lag period of the growth of Candida albicans in four blood culture media, under a variety of conditions of incubation. The media compared were Bactec 6B, brain-heart infusion, malt extract broth and Sabourauds liquid medium. All four media were incubated under the eight possible permutations of the following conditions: 37 degrees C or 30 degrees C, vented or unvented, unshaken or constantly shaken. Then, using the incubation conditions found to be most favourable, minimum detection times for C. albicans were compared in the four media. The combination of incubation of the cultures at 37 degrees C, venting and constant-shaking, produced the fastest generation time with the minimum lag period. Of the media, Bactec 6B medium had the shortest lag period under these conditions while brain-heart infusion had the lowest MGT overall. Sabourauds liquid medium, which resulted in the most favourable combination of generation time and lag period, proved superior to the other media for the recovery of C. albicans.

Blood↗
PubMed1988

In-vitro adherence of oral streptococci in the presence of sucrose and its relationship to cariogenicity in the rat.

Streptococcus sanguis I gave a significantly greater percentage coverage (cell-pellicle attachment) of saliva-coated glass in the presence of sucrose than did Strep. sanguis II (p less than 0.025), and both these gave greater percentage coverages than the other species tested, between which no significant differences were noted. There was a large number of significant differences in clump size (cell-cell attachment) between species-pairs. Among the mutans streptococci, there were significant differences in the percentage coverage between Streptococcus rattus/Streptococcus mutans (p less than 0.05) and Strep. rattus/Streptococcus sobrinus (p less than 0.01), and in clump size between all species-pairs with the exception of Streptococcus cricetus or Strep. sobrinus and Strep. mutans. The rank order of species in relation to fissure caries was mutans streptococci greater than Streptococcus salivarius greater than Streptococcus milleri greater than Strep. sanguis greater than Streptococcus faecalis greater than Streptococcus mitis greater than Streptococcus lactis. There was a significant correlation between percentage coverage in vitro and fissure caries in vivo for strains of Strep. sanguis (p less than 0.05) and pooled strains of Strep. mitis and Strep. sanguis (p less than 0.01). On comparing data for adherence in the presence or the absence of sucrose, the sugar had no effect on the percentage coverage of the seven species tested, but significantly increased the clump size of the mutans streptococci (p less than 0.01) and Strep. sanguis (p less than 0.05).

Animals↗
PubMed1988

Partial characterisation of the inhibitory substances produced by Streptococcus oralis and related species.

The production of inhibitory substances was sought by deferred antagonism. Streptococcus oralis, Streptococcus mitis and Streptococcus sanguis produced bactericidal concentrations of hydrogen peroxide, but no detectable bacteriocin. Actinomycetes and Neisseria pharyngis were particularly susceptible to the lethal action of hydrogen peroxide. Streptococcus milleri produced bactericidal concentrations of hydrogen peroxide and bacteriocin-like substances. S. oralis strains were inhibited by the bacteriocin-like products of strains of Streptococcus bovis, Streptococcus faecalis, Streptococcus mutans and Streptococcus salivarius. Inhibition was due neither to complete bacteriophage nor to fermentation end-products. Extracellular polysaccharides formed during growth could not protect sensitive strains from the effect of hydrogen peroxide or bacteriocin-like substances.

Actinomycetales↗
PubMed1987

Relative cariogenicity and in-vivo plaque-forming ability of the bacterium Streptococcus oralis in gnotobiotic WAG/RIJ rats.

The rats, fed a high sucrose diet, were mono-infected with seven strains of Streptococcus oralis. Moderate levels of caries were induced by four strains, and three others induced low levels. Approximal lesions were induced by two strains; no buccal/lingual lesions were produced. Scanning electron microscopy showed that all strains colonized the tooth fissures, some strains producing a moderately abundant and dense plaque. The most cariogenic strains (PB178, PB180 and PB186) induced similar levels of caries to Streptococcus milleri.

Animals↗
PubMed1987

Lethal challenge of gnotobiotic weanling rats with bacterial isolates from cases of sudden infant death syndrome (SIDS).

An attempt was made to produce an animal model of sudden infant death syndrome (SIDS). The experimental animals (germ free weanling rats) were exposed to nasopharyngeal isolates from cases of SIDS to test the hypothesis that common bacteria may have an aetiological role in the disease. Negative results were obtained when the strains were tested in isolation, but certain combinations of organisms (specifically some Staphylococcus aureus and Escherichia coli) killed the animals rapidly (less than 18 hours) without prolonged terminal illness. Post mortem histological findings were consistent with those of SIDS. The lethal toxigenic potential of nasopharyngeal bacteria, which are regarded as harmless in adults, should be reconsidered in respect of the aetiology of SIDS.

Animals↗
PubMed1987

A simple method for determining extracellular polysaccharide-producing ability of oral streptococci.

A simple method is described for determining the types of extracellular polysaccharides produced by oral streptococci. The method yields quantitative results in which the amount of polysaccharides produced is normalised with respect to DNA. Results correlate well with previously published data for oral streptococci, except in the case of Streptococcus oralis for which there is no previously published data. All species within the mutans group produced both soluble and insoluble glucan; while soluble fructan was only produced by strains of Streptococcus rattus and Streptococcus mutans. The major extracellular polysaccharide produced by Streptococcus salivarius was soluble fructan, although some strains produced soluble and insoluble glucan. Most Streptococcus sanguis strains produced soluble and insoluble glucan. Soluble fructan was produced by some strains of S. sanguis and S. oralis. The latter also produced soluble and insoluble glucan. No detectable extracellular polysaccharide was elaborated by Streptococcus milleri, Streptococcus faecalis or Streptococcus lactis.

Bacteriological Techniques↗
PubMed1985

Gas chromatography/mass spectrometry of bacterial amines.

Bacterial amines were examined by gas chromatography/mass spectrometry. Under electron impact all trifluoroacetamides exhibited peaks at m/z 69 due to [CF3]+. Many trifluoroacetamides also showed peaks at m/z 97 corresponding to the [COCF3]+ ion fragment. The spectra of n-alkyl and aralkyl trifluoroacetamides were consistent with the spectra and their interpretations in the earlier literature. Molecular ions were of low abundance for all alkyl trifluoroacetamides having alkyl chains longer than two carbon atoms. Chemical ionization gave molecular weight information in all cases. Most peaks observed were molecular addition products, e.g. [M + H]+ and [M + NH4]+. Application of chemical ionization mass spectrometry to analysis of bacterial amines revealed the production of beta-phenylethylamine, n-decylamine, 1,4-diaminobutane and 1,5-diaminopentane by Clostridium histolyticum; whereas both Clostridium bifermentans and Clostridium oedematiens produced beta-phenylethylamine. The latter organism also produced a peak with a retention time similar to that of an authentic amylamine derivative.

Amines↗
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↗
PubMed1985

The cariogenicity of sucrose, glucose and maize starch in gnotobiotic rats mono-infected with strains of the bacteria Streptococcus mutans, Streptococcus salivarius and Streptococcus milleri.

Twenty-one-day-old weanling gnotobiotic WAG/RIJ rats were mono-infected with Streptococcus mutans NCTC 10832, Streptococcus salivarius JMB or Streptococcus milleri NCTC 11169, and maintained on a high carbohydrate diet containing sucrose, glucose or maize starch for 21-days. Fissure caries developed with all combinations of streptococcal strain and carbohydrate except maize starch/Streptococcus salivarius JMB. Caries incidence was highest with Streptococcus mutans NCTC 10832. For all species, the ranking of carbohydrates by cariogenic potential was sucrose greater than glucose greater than maize starch.

Animals↗
PubMed1985

The comparative cariogenicity and plaque-forming ability in vivo of four species of the bacterium Actinomyces in gnotobiotic rats.

Gnotobiotic WAG/RIJ rats on a high sucrose diet were monoinfected with 12 strains of Actinomyces spp. Moderate levels of caries were induced by a single strain of Actinomyces naeslundii and low levels by two strains of Actinomyces viscosus, three strains of A. naeslundii and one strain of Actinomyces israelii. No caries was induced by single strains of A. viscosus and A. israelii or by three Actinomyces odontolyticus strains. Only fissure caries was observed. Scanning electron microscopy showed that all strains colonized the fissures and most colonized the lingual surface of the teeth, but to a limited extent. Production of abundant and dense plaque was not always accompanied by caries.

Actinomyces↗
PubMed1984

The production of dental plaque and caries by the bacterium Streptococcus salivarius in gnotobiotic WAG/RIJ rats.

The abilities of ten strains of Streptococcus salivarius to colonize rat molars and to induce caries were determined using mono-infected germ-free rats. Scanning electron microscopy revealed the production of micro-colonies and spheroids by Strep. salivarius on exposed surfaces of molar teeth, and abundant dense plaque formation in fissures. Most strains colonized fissures and smooth surfaces as effectively as Streptococcus mutans NCTC 10832, yet produced no buccal or lingual lesions. The four K- strains of Strep. salivarius produced more approximal lesions than the K+ strains but fewer lesions than Strep. mutans. All but one Strep. salivarius strain fell into the high-caries category, together with Strep. mutans. They were all more cariogenic than either Streptococcus milleri NCTC 11169 or Streptococcus faecalis 47.

Animals↗
PubMed1984

In-vivo dental plaque-forming ability and relative cariogenicity of the bacteria Streptococcus mitis and Streptococcus sanguis I and II in mono-infected gnotobiotic rats.

Sixteen strains of Streptococcus mitis, Streptococcus sanguis I and Strep. sanguis II were tested for cariogenic potential and in-vivo plaque-forming ability in a gnotobiotic WAG/RIJ rat test system. All strains produced far less fissure plaque in vivo than strains of Streptococcus milleri or Streptococcus mutans. There was less extracellular matrix around cells of Strep. mitis or Strep. sanguis than around Strep. mutans, in the fissures. Dense sheets of cells were observed only with Strep. mutans. Some localized colonization of exposed smooth surfaces occurred with most strains. Strep. mitis produced no caries in three tests, low-caries scores in two tests and high-caries scores in one test. A single strain of Strep. mitis produced a highly-cariogenic variant able to ferment raffinose. Strep. sanguis I induced low-levels of caries in 12 tests; one test of NCTC 7865 produced moderate levels of caries, and another test of 311 produced no caries. Strep. sanguis 311 was dextran-negative. Strep. sanguis II strains induced no caries in three tests, low caries scores in six tests and moderate levels of caries with Strep. sanguis 402. No strain of Strep. mitis or Strep. sanguis was able to induce smooth-surface lesions.

Animals↗