口腔环境因素对血型链球菌和变形链球菌生长的影响 Ⅰ．粘蛋白的影响

采用连续培养方法，以粘蛋白作为化学限定培养基中的限定性因子，观察血型链球菌（以下简称血链菌）和变形链球菌（以下称简称变链菌）Ｉｎｇｂｒｉｔｔ（ｃ）的生长状态。结果显示变链菌不能生长于以粘蛋白作为唯一营养源的培养基中，而血链菌可以生长；两菌混合培养时的生长量均有所提高，表明两菌有协同降解粘蛋白作用。     

口腔环境因素对血型链球菌和变形链球菌生长的影响：II.氧的影响

口腔的链球菌族属于微需氧菌，易受到氧代谢产物的抑制作用，作者采用连续培养方法，观察血型链球菌（以下简称为血链菌）３４和变形链球菌（以下简称变链菌）Ｉｎｇｂｒｉｔｔ（ｃ）在有氧情况下的生长状态，得出血链菌３４的耐氧能力高于变链菌Ｉｎｇｂｒｉｔｔ（ｃ）的结果。这一结果与血链菌为牙菌斑的先锋定殖菌的现象相一致。而变链菌的耐氧能力差使其生长，以及致龋作用对牙菌斑的内环境有一定的依赖性。     

血型链球菌和变形链球菌葡糖基转移酶的对比分析

通过对血型链球菌（以下简称血链菌）３４和变形链球菌（以下简称变链菌）Ｉｎｇｂｒｉｔｔ（ｃ）葡糖基转移酶（ＧＴＦ）的活性测定，以及合成胞外多糖的对比分析，得出以下结论：（１）在相同培养条件下，提取血链菌３４的胞外ＧＴＦ的酶蛋白量比变链菌Ｉｎｇｂｒｉｔｔ（ｃ）多，而变链菌Ｉｎｇｂｒｉｔｔ（ｃ）胞外ＧＴＦ的酶活性高于血链菌３４；（２）血链菌３４的胞外ＧＴＦ酶具有合成ＩＧ和ＳＧ的能力，与变链菌Ｉｎｇｂｒｉｔｔ（ｃ）的胞外ＧＴＦ酶一样具有多形性，血链菌可以催化形成足够的葡聚糖来激活变链菌引物依赖型的ＧＴＦ酶，对牙菌斑的后继定殖菌是非常有利的；（３）获取血链菌３４的ＧＴＦ纯酶制剂比变链菌Ｉｎｇｂｒｉｔｔ（ｃ）容易。     

口腔环境因素对血型链球菌和变形链球菌生长的影响 Ⅱ、氧的影响

口腔的链球菌族属于微需氧菌，易受到氧代谢产物的抑制作用，作者采用连续培养方法，观察血型链球菌（以下简称为血链菌）３４和变形链球菌（以下简称变链菌）Ｉｎｇｂｒｉｔｔ（ｃ）在有氧情况下的生长状态，得出血链菌３４的耐氧能力高于变链菌Ｉｎｇｂｒｉｔｔ（ｃ）的结果，这一结果与血链菌为牙菌斑的先锋定殖菌的现象相一致，而变链菌的耐氧能力差使其生长，以及致龋作用对牙菌斑的内环境有一定的依赖性。     

山梨醇对变形链球菌致龋性影响的体外实验研究

作者分别在３％蔗糖培养基，５％山梨醇培养基和含５％山梨醇的蔗糖培养基中培养变形链球菌，比较三种培养基中变链菌在多个环节上的致龋能力。发现变链菌经三种培养后，吸附能力无差别，但在山梨醇中培养时，变链菌生长缓慢，产酸少，特别是乳酸量远低于另两组，培养基ｐＨ值下降轻微。在蔗糖培养基中加入山梨醇后，细菌的生长和产酸都有所减弱。表明山梨酵致龋性低，代替蔗糖可减少龋齿。     

山梨醇对变形链球菌致龋性影响的体外实验研究

作者分别在３％蔗糖培养基，５％山梨醇培养基和含５％山梨醇的蔗糖培养其中培养变形链球菌，比较三种培养其中变链菌在多个环节上的臻龋能力。发现变链菌经三种培养后，吸附能力无差别，但在山梨醇中培养时，变链菌生长缓慢，产酸少，特别是乳酸量远低另两组，培养基ＰＨ值下降轻微。     

中药五倍子对变形链球菌及远缘链球菌抑制作用的体外研究

目的：研究五倍子及其主要成分鞣酸在体外对变链菌及远缘链球菌的抑制作用，并摸索适宜剂型和浓度。方法：本实验采用纸片扩散法研究五种浓度五倍子煎剂，五倍子浸剂，鞣酸标准品抑制变链菌及远缘链球菌生长的作用。结果：65.2mL/L以上浓度五倍子煎剂，浸剂，鞣酸对变链菌及远缘链球菌生长均有抑制作用，其中五倍子浸剂抑菌作用最强。抑菌作用随着各剂型浓度的增国而增强。结论：五倍子可以抑制变链菌及远缘链球菌生长，其中浸剂效果最优，鞣酸组效果较差，可初步推测五倍子中含有其他协同鞣酸抑菌的成分。     

变形链球菌蔗糖酶Ⅱ基因片段的PCR扩增（一）

根据变形链球菌（以下简称变链菌）ＧＳ５ＳｃｒＡ基因核苷酸序列，设计并合成了一对寡核苷酸引物，采用ＰＣＲ方法对１３株变链菌、２３株口腔常居菌进行扩增，结果全部变链菌及部分口腔常居菌均出现４３２ｂｐＤＮＡ片段。说明该基因部分序列广泛存在于变链菌及部分口腔常居菌，这为研究口腔细菌的微生态关系提供了新的信息。     

口腔链球菌的耐酸机制

在口腔天然菌群中,链球菌占的比例最大,包括血链球菌、轻链球菌、唾液链球菌和变形链球菌(以下简称变链菌)等。口腔链球菌系产酸菌,能很快发酵糖产酸,导致环境pH下降。因此,链球菌在低pH环境中生长及继续代谢碳水化合物产酸是学者们而对的一大问题。本文对各种链球菌的耐酸机制进行综述。 一、质子移位膜ATP酶 1.质子移位膜ATP酶的作用 通过质子移位膜ATP酶(proton-translocating membraneATPase,H~ -ATPaxc或F-ATPase)抵抗酸的攻击是变链菌的主要耐酸机制。H~ -ATPase是与细菌胞膜结合的蛋白酶,由BF0和BF1两部分组成,兼有ATP水解和ATP合成的双重作用,可通过消耗胞内ATP将质子H~ 移出胞外,以维持胞内相对中性。BF0由疏水性蛋白组成,埋在原生质膜的磷脂中,起     

变形链球菌的粘附机理

变形链球菌（变链菌）在牙面上的粘附和定居是龋病发生的始动因子。变链菌的葡萄糖基转移酶、表面大分子物质等自身生物学特性可能参与了变链菌在牙面上粘附定居的全过程。唾液中的某些蛋白作为变链菌粘附的受体促进其粘附，而另一些唾液蛋白凝集变链菌而有利其清除。本文对与变链菌粘附有关的自身生物学特性和唾液蛋白进行了综述。     

Synergistic degradation of mucin by Streptococcus oralis and Streptococcus sanguis in mixed chemostat cultures

Oral streptococci can grow in mucin by utilizing the oligosaccharide chains as a source of carbohydrate. The degradation of the oligosaccharides by these species is accomplished by exoglycosidase activities. In this experiment, it was investigated whether strains from different species could cooperate in the release of sugars from the mucin oligosaccharide. To this end, Streptococcus sanguis Ny 584 and Streptococcus oralis strain Ny 586 were grown continuously in a chemically-defined medium, with pig gastric mucin as the growth-limiting source of carbohydrate. In pure cultures, strain Ny 586 attained approximately three-fold-higher cell densities than did strain Ny 584 in the mucin medium. This was in accordance with the observation that S. oralis Ny 586 exhibited fucosidase activity, as indicated by the presence of fucose in the culture fluid. In contrast, strain Ny 584 has no fucosidase activity against mucin, and therefore cannot attack fucose-ending oligosaccharide chains. Stable mixed cultures of the strains were obtained. It appeared that S. sanguis Ny 584 reached significantly higher cell densities in mixed cultures with S. oralis Ny 586 than in pure culture. Stimulation of the growth of strain Ny 584 was probably due to the generation of non-fucose-ending oligosaccharide chains by fucosidase from strain Ny 586. It is concluded that the synergistic degradation of oligosaccharides in glycoproteins is a potential factor influencing the streptococcal populations in the mouth.     

Water-soluble glucans from Streptococcus mutans strain Ing-Britt as an energy source for bacterial growth

Two fractions of water-soluble glucans with different molecular weight were produced by Streptococcus mutans IB. The larger glucan had a molecular weight of about 40,000. The molecular weight of the small glucan was estimated to be 4,100 by gel filtration chromatography and by biochemical methods. These glucans were tested for their ability to initiate and support growth of S. mutans IB and Streptococcus sanguis 903. S. sanguis 903 could grow with the low molecular weight glucan at a reduced rate compared with glucose. S. mutans IB could not utilize any of the glucans. No endo- or exo-glucanase activities could be detected in culture supernatants of any of the strains. In addition to maltose S. sanguis 903 could also utilize maltotriose, maltopentaose and maltoheptaose for growth while S. mutans IB could not grow with maltopentaose or maltoheptaose.     

Effect of penicillin on Streptococcus mutans, Streptococcus sanguis and lactobacilli in hamsters and in man

The effect of penicillin on the number of oral Streptococcus mutans, Streptococcus sanguis and lactobacilli in hamsters and in man was investigated. This is of interest as S. mutans and lactobacilli are involved in the carious process while S. sanguis is not. Hamsters infected with both S. mutans and S. sanguis or only S. sanguis received penicillin in their drinking water for 14 d. The treatment reduced the proportion of S. mutans and S. sanguis in dental plaque to undetectable levels. After the penicillin treatment the population of S. mutans and S. sanguis gradually increased. In man, the effect of oral penicillin therapy was examined in 21 adults with more than 2 X 10(5) S. mutans per ml saliva. The penicillin treatment had almost no effect on the numbers of S. sanguis and lactobacilli, but a pronounced decrease in the number of S. mutans was observed. The duration of this effect, however, was short. Consequently, such treatment alone is of limited value for the control of the oral infection of these microorganisms.     

Effect of penicillin on Streptococcus mutans, Streptococcus sanguis and lactobacilli in hamsters and in man

Abstract – The effect of penicillin on the numbers of oral Streptococcus mutans, Streptococcus sanguis and lactobadlii in hamsters and in man was investigated. This is of interest as S. mutans and lactobacilli are involved in the carious process while S. sanguis is not. Hamsters infected with both S. mutans and S. sanguis or only S. sanguis received penicillin in their drinking water for 14 d. The treatment reduced the proportion of S. mutants and S. sanguis in dental plaque to undetectable levels. After the penicillin treatment the population of S. mutans and S. sanguis gradually increased. In man, the effect of oral penicillin therapy was examined in 21 adults with more than 2 × 10⁵ S. mutans per ml saliva. The penicillin treatment had almost no effect on the numbers of S. sanguis and lactobacilli, but a pronounced decrease in the number of S. mutans was observed. The duration of this effect, however, was short. Consequently, such treatment alone is of limited value for the control of the oral infection of these microorganisms.     

Effect of chlorhexidine on the relative proportions of Streptococcus mutans and Streptococcus sanguis in hamster plaque

abstract — The effect of chlorhexidine on the proportions of Streptococcus mutans and Streptococcus sanguis in plaque was studied in hamsters fed a diet containing 28% sucrose. In animals given chlorhexidine in their drinking water for 10 d a decrease in the population of S. mutans and an increase of S. sanguis occurred in the plaque. Following the removal of chlorhexidine the population of S. mutans increased again in the presence of sucrose and the number of S. sanguis returned to initial values. When animals were given a sucrose-free diet the low proportion of S. mutans observed following the short-term chlorhexidine period persisted. These data indicate that there is an inverse relationship between the number of S. sanguis and S. mutans in plaque and that the sensitivity in vivo of S. mutans to chlorhexidine can be used to suppress the population of S. mutans with a concomitant rise in the proportion of S. sanguis .     

Effect of chlorhexidine on the relative proportions of Streptococcus mutans and Streptococcus sanguis in hamster plaque.

The effect of chlorhexidine on the proportions of Streptococcus mutans and Streptococcus sanguis in plaque was studied in hamsters fed a diet containing 28% sucrose. In animals given chlorhexidine in their drinking water for 10 d a decrease in the population of S. mutans and an increase of S. sanguis occurred in the plaque. Following the removal of chlorhexidine the population of S. mutans increased again in the presence of sucrose and the number of S. sanguis returned to initial values. When animals were given a sucrose-free diet the low proportion of S. mutans observed following the short-term chlorhexidine period persisted. These data indicate that there is an inverse relationship between the number of S. sanguis and S. mutans in plaque and that the sensitivity in vivo of S. mutans to chlorheximide can be used to suppress the population of S. mutans with a concomitant rise in the proportion of S. sanguis.     

Effects of chlorhexidine and iodine on in vitro plaques of Streptococcus mutans and Streptococcus sanguis

Abstract – Both chlorhexidine and iodine showed greater antimicrobial effect on in vitro grown S. mutans plaque than on plaque composed of S. sanguis . One treatment with iodine for 8 min inhibited the acid production of S. mutans plaque whereas S. sanguis plaque required 20 min to be similarly affected. In contrast one treatment with chlorhexidine for up to 20 min did not completely inhibit the acid production of plaque of either microorganism. Repeated short term exposures increased the bactericidal effect of chlorhexidine but not that of iodine. The difference in antimicrobial effect between chlorhexidine and that of iodine on S. mutans and S. sanguis should be investigated in persons heavily infected by S. mutans .     

Evaluation of antimicrobial activity in vitro of ten root canal sealers on Streptococcus sanguis and Streptococcus mutans

The antimicrobial activity of ten root canal sealers was studied on Streptococcus sanguis and Streptococcus mutans. One hundred plates of trypticase soy agar-sheep red blood cell (10%), each with four distinct 3 mm diameter wells, were divided into two groups of 50 by means of the Lawn technique; one group was inoculated with S. sanguis and the other with S. mutans. Four milligrams of each root canal sealer was placed in each of three wells in 10 plates (five plates of each inoculant); the fourth well was left empty as a control site. Plates were incubated at 37 degrees C and checked after 2, 7, and 14 days. All root canal sealers inhibited growth of both organisms. The inhibitory zones for S. sanguis were larger than inhibitory zones for S. mutans for all tested sealers, except Diaket. Dentinol, Kerr, and Tubliseal had significantly more inhibitory effect on S. sanguis than did other tested sealers (p less than 0.05). Diaket had superior inhibition on S. mutans.