An in vivo clinical program investigated the relationship among oral microorganisms, bacterial plaque, and calculus formation. Benzethonium chloride, cetylpyridinium chloride, and Vancomycin provided a moderate reduction in bacterial plaque accumulation (30 to 35%). Hexachlorophene was relatively ineffective. One antibiotic, CC 10232, consistently furnished substantial reductions in plaque formation (70 to 77%) and calculus formation (75%). Only Vancomycin significantly reduced the gram-positive population. None of the antimicrobial agents caused changes in the staphylococcal or yeast populations.
Two groups of littermated hamsters with polyglucan‐forming streptococci in their oral flora, were set up in identical but separate quarters and fed a cariogenic diet. The control group was untreated, whereas the test group was inoculated orally with polyfructan‐forming streptococci (Strain SS‐2) by swabbing the teeth for four days. After forty‐four days, the animals were evaluated for dental caries, bone resorption and gingival mast cell population density. The inoculated hamsters showed a 2.24 X increase in dental caries, an 1.82 X increase in bone resorption, and a 1.50 X increase in mast cell numbers. The increases in each of these three parameters was statistically highly significant. The role of polyfructan‐forming streptococci in causing dental caries directly, and increasing numbers of mast cells with accompanying bone resorption along the alveolar crest and other periodontal disease symptoms is discussed.
A defined transforming medium (DTM) containing buffer and 5 to 10,g per ml of deoxyribonucleic acid was developed to study the physical and chemical requirements for optimal transformation in streptococcal strain SBE. Optimal transformation in DTM occurred at pH 7.5 and 7.0 in 0.07 M sodium phosphate buffer and 0.05 M tris(hydroxymethyl)aminomethane buffer, respectively. In the presence of either a monovalent or a divalent cation, transformation was stimulated maximally by Mn+2 (108 M) and K+ (0.05 M). Other cations tested (Na+, Mg+2, Ca+2) were less stimulatory. A mixture of K+ and Mn+2 stimulated transformation to a level higher than either cation alone. Kinetic studies showed that the stimulating effect of cations was greatest during the early part of the transformation reaction and decreased with time. Transformation was inhibited by CU+2 (105 M) and Mn+2 (102 M). Ethylenediaminetetraacetic acid (EDTA) inhibited transformation at 10-M. The inhibition by EDTA could be overcome by Mn+2 during the early part of the transformation reaction. Genetic transformation of bacteria by deoxyribonucleic acid (DNA) is a multiphasic process involving the attachment of DNA to a microorganism and its subsequent transport into the cell where it is incorporated into the recipient cell genome. Although DNA attachment and uptake by competent cells has been studied extensively, many of these studies were done under poorly defined conditions. Studies in which Bacillus subtilis (16), Haemophilus influenzae (1), and B. licheniformis (8) were used in a defined environment to study DNA attachment and uptake demonstrated that there are very definite conditions necessary for this process to proceed rapidly. Both monovalent and divalent cations, as well as pH, temperature, and inhibitors, affect this phase of transformation. This investigation was conducted to determine the ability of various physical and chemical environments to enhance the transformation of streptococcal strain SBE, and to study the mechanisms involved. A preliminary report of these data was presented (Schlissel and Sword, Bacteriol. Proc., p. 36, 1966). MATERIALS AND METHODS Cultures. The transformable strain of group H streptococcus, SBE, used exclusively in this study was 1357
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