五倍子对变形链球菌及远缘链球菌产酸影响的体外研究

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产酸作用有何影响。方法 本实验采用气相色谱研究50％五倍子浸剂、37％鞣酸标准品、2％氟化钠液对变链菌及远缘链球菌产酸作用的影响。结果 50％五倍子浸剂有机酸含量最少,其次分别为2％氟化钠组、37％鞣酸标准品组,3组间无统计学的差异。结论 五倍子对变链菌及远缘链球菌产酸有较强的抑制作用,其作用与氟化钠相当。     

茶色素抑制变形链球菌的实验研究

目的研究茶色素对变形链球菌的抑制作用及其机制。方法以茶多酚为对照,采用液体稀释法体外抑菌实验比较不同纯度茶色素对变链菌族的变形链球菌和远缘链球菌生长、产酸和形态学的影响。结果纯度为20%、40%、60%的茶色素均能抑制变链菌生长,其中纯度为40%的茶色素抑菌效果最佳,与纯度90%的茶多酚相当,两者均能明显抑制变链菌产酸(P<0.05),透射电镜观察发现茶色素主要引起变链菌胞质空泡性变,茶多酚则破坏细菌细胞壁,两者抑菌机理不同。结论不同纯度茶色素中,纯度为40%的茶色素抑制变链菌效果最佳,抑菌过程中茶色素各个组分存在着协同作用。     

洗必泰对变形链球菌、远缘链球菌耐氟菌株与亲代菌株生长抑制的测定

目的：通过洗必泰对变形链球菌、远缘链球菌耐氟菌株与亲代菌株生长抑制的测定，探讨一种新的防龋途径。方法：将醋酸洗必泰液稀释成不同的浓度，分别加入变形链球菌、远缘链球菌及耐氟菌株菌悬液，测得最小抑菌浓度（MIC）、最小杀菌浓度（MBC）。结果：洗必泰对变形链球菌、远缘链球菌及耐氟菌株均有抑菌、杀菌作用，4种细菌最小抑菌浓度（MIC）均值为338μg/L，最小杀菌浓度（MBC）均值为375μg/L。结论：洗必泰可有效抑制变形链球菌、远缘链球菌及耐氟菌株生长。     

稻芽粗提物抑制变异链球菌的体外实验研究

目的:观察稻芽粗提物对变异链球菌的抑制作用。方法:采用醇提法制取稻芽的药物粗提物,并测量其在不同药物浓度下对变异链球菌生长、黏附、产酸等作用的抑制效果。结果:稻芽粗提物抑制变异链球菌(变链菌)体外生长的最低抑菌浓度(MIC)值为6.25 mg/mL,当稻芽粗提物浓度≥0.78 mg/mL时有较明显的抑制变链菌黏附的作用,当稻芽粗提物浓度≥0.39 mg/mL即有较明显的抑制变链菌产酸的作用。结论:稻芽粗提物对变异链球菌有一定的抑制作用。     

甲壳胺复合物影响变形链球菌生长、代谢的实验室研究

目的观察甲壳胺、荼多酚单一组分及甲壳胺复合物对口腔致龋菌生长、粘附和代谢产酸的影响。方法采用0．5％甲壳胺、0．25％茶多酚以及同等浓度的甲壳胺、茶多酚复合物对变形链球菌、远缘链球菌进行抑菌实验、抗粘附实验、解吸附实验以及产酸抑制实验。结果0．5％甲壳胺可抑制变链菌对毛细管的粘附．并促进附着于粘附板上的变链菌脱落，产酸实验中，0．5％甲壳胺和0．25％荼多酚可减少终末pH下降和乳酸量生成，甲壳胺复合物对变链菌的抑制粘附和产酸作用明显高于单一成分组。结论甲壳胺复合物对口腔致龋菌生长、粘附和代谢产酸均有明显的抑制，提示甲壳胺及荼多酚作为天然抗菌斑附着剂，用于龋病预防具有一定的价值和可行性。     

变链菌分离株的形态、生理生化和遗传学鉴定

目的：探讨形态学和生理生化反应与DNA碱基含量测定鉴定变链菌和元缘链球菌临床分离株的一致性。方法：采用形态学和生理生化试验鉴定变链菌和远缘链球菌临床分离株，采用高效反相液相色谱法测定细菌DNA G＋Cmol%以检验生化鉴定的准确性。结果:形态及生化鉴定为变链菌和远缘链球菌的临床分离株，其DNA碱基含量分别为37．52和45．19，各自位于变链菌和远缘链球菌36－38和44－46的G＋Cmol％参考范围。结论：变链菌和远缘链球菌的生化鉴定结果与DNA G＋Cmol％测定结果一致。通过形态及生理生化鉴定基本可以鉴定变链菌和远缘链球菌。     

猛性龋儿童变链菌分离株耐酸性实验研究

目的：确定猛性龋儿童变链菌和远缘链球菌临床株的耐酸性。方法：采用紫外分光光度计比较猛性龋、非猛性龋、无龋儿童变链菌（各6株）和远缘链球菌（猛性龋儿童6株,非猛性龋和无龋儿童各3株）临床株在体外不同初始pH条件下的生长情况。结果：初始pH4．5－5．5条件下,各组变链菌生长抑制程度均明显大于远缘链球菌（P＜0．05）。初始pH4．5条件下,猛性龋儿童远缘链球菌分离株耐酸性明显强于非猛性龋和无龋儿童分离菌株（P＜0．05）。结论：远缘链球菌的耐酸性强于变链菌;猛性龋儿童远缘链球菌分离株耐酸性强。     

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。     

玉洁纯、硫酸锌对口腔主要致龋菌生长产酸的影响

目的：评价玉洁纯、硫酸锌对口腔主要致龋菌的影响,确定抑制细菌所需的浓度。方法：使用紫外分光光度计及ｐＨ电极检测不同浓度的药物及两者相对配伍使用时对口腔主要致龋菌－变形链球菌和远缘链球菌的抑制效果。结果：玉洁纯、硫酸锌均能有效地抑制变链和远链的生产和产酸,硫酸锌不能增强玉洁纯的抑制效果。结论：初步认为玉洁纯可作为龋病预防用药,硫酸锌在配方中的作用有待进一步探讨。     

复方五倍子煎剂对变形链球菌抑菌作用的实验研究

目的:观察复方五倍子制剂对变形链球菌的抑制作用。方法:将五倍子、大黄、甘草等10味中草药制成煎剂(GER) ,测量其不同浓度对变形链球菌生长、产酸、粘附等作用的抑制效果。结果:当GRE浓度为10 0 %时(最终浓度2 0 %W /V) ,细菌生长量仅为对照组的3 5 .6% ;粘附率下降12 .7% ;pH值升高1.5 4。药物浓度为5 0 %时(最终浓度10 %W /V) ,与对照组比较,细菌生长和粘附作用分别下降43 .8%和10 .6% ,pH值升高1.18。结论:GRE对变形链球菌有一定的抑制作用。     

中药五倍子防龋的动物实验研究

目的研究五倍子在动物口腔内对变链菌生长及龋病发生、发展的影响。方法给大鼠感染致龋菌,并饲以致龋饲料2000#,分别用五倍子浸剂、氟化钠水溶液、蒸馏水给3组大鼠施药,用唾液取样细菌培养及Keyes龋齿评分法观察五倍子对变链菌在大鼠口内生长繁殖以及对龋齿发生发展的影响。结果变链菌计数五倍子组少于蒸馏水组（P<0.01）,与氟化钠组间无显著差异（P>0.05）。Keyes记分结果,五倍子组E级龋损和Ds级龋损均低于蒸馏水组（P<0.01）,与氟化钠组无差异(P>0.05)。Dm级龋损仅见于蒸馏水组。结论五倍子可以抑制大鼠口腔变链菌的生长和龋病发生、发展,其效果与氟化钠相当,有可能成为一种新型的防龋药物。     

远缘链球菌与乳牙龋病关系的研究

目的：探讨远缘链球菌与乳牙龋病的关系。方法：采有ＴＹＣＳＢ培养基作细菌筛选,运用分子遗传学手段即ＤＮＡ的Ｇ＋ Ｃ ｍｏｌ％ 测定作最终鉴定。结果：患龋儿童组与无龋儿童组变形链球菌检出率有显著差异（Ｐ＜０ ．０１）,远缘链球菌检出率有显著差异（Ｐ＜ ０．０５） ;患龋儿童组中能同时检出变形链球菌和远缘链球菌的群体,其龋失补牙数、龋失补牙面数及平滑面龋数均与只能检出变形链球菌的群体有显著差异（ Ｐ＜ ０．０１） 。结论：变形链球菌是龋病的主要致病菌,远缘链球菌对龋病过程有协同作用,与乳牙平滑面龋的发生、发展有关。     

酪蛋白磷酸多肽体外抑菌实验研究

目的 :体外观察酪蛋白磷酸多肽 (caseinphosphopeptides,CPP)对主要致龋菌变形链球菌、远缘链球菌的直接作用。方法 :将细菌活化 ,并接种于培养基内 ,通过琼脂糖扩散培养及纸片法 ,观察细菌生长和各组的抑菌程度。结果 :CPP对变形链球菌和远缘链球菌无直接抑菌作用。结论 :CPP如作为生物防龋制剂用于临床 ,尚需添加其他无毒有效的抑菌剂 ,以提高其防龋效能。     

变形链球菌和远缘链球菌耐氟菌株超微结构观察

目的：探讨变形链球菌和远缘链球菌耐氟突变后，其超微结构变化及氟化物对细菌结构的影响。方法：将变形链球菌和远缘链球菌分为3组：A为正常对照组；B为加氟孵育组；C为耐氟菌株组。透射电镜观察3组细菌的超微结构。结果：与正常亲代菌株相比，加氟孵育后的菌株及耐氟菌株菌体出现不同程度超微结构改变，包括胞浆电子密度减低，细胞肿胀，内容物外溢，远缘链球菌链状结构消失等。结论：变形链球菌和远缘链球菌与氟共同孵育及耐氟突变后，其超微结构发生了改变，表现为自溶活动及解链活动增强。     

抗变形链球菌鸡卵黄抗体对变形链球菌合成葡聚糖影响的实验研究

目的 研究抗变形链球菌鸡卵黄抗体（IgY）对变形链球菌合成葡聚糖的影响。方法 用蒽酮法测定各浓度组IgY使用后，定量菌在单位时间内合成葡聚糖的量。结果 IgY抗体对血清c型及血清g型变形链球菌合成胞外多糖均有影响，各浓度组IgY对合成胞外多糖的影响力有随着浓度升主而增强的趋势。1：16浓度组起有效，1：2浓度组的抑制作用最强（P＜0.05）。结论 IgY可以减少变链菌合成葡聚糖。     

In vitro inhibitory effects of Polygonum cuspidatum on bacterial viability and virulence factors of Streptococcus mutans and Streptococcus sobrinus

OBJECTIVES: Polygonum cuspidatum has been used in Korean folk medicine to improve oral hygiene. This study was performed to evaluate the effects of methanol extract from root of P. cuspidatum (MEP) on bacterial viability and the virulence factors of Streptococcus mutans and Streptococcus sobrinus. METHODS: To test the effects of MEP on bacterial viability, we determined the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against 20 bacterial strains, including S. mutans and S. sobrinus, using a micro-dilution assay. In case of S. mutans and S. sobrinus, the assays for time-kill and bacterial growth rate at sub-MIC concentrations were also performed. To determine effects of the extract on the virulence factors of S. mutans and S. sobrinus, the assays for sucrose-dependent adherence, water-insoluble glucan formation, glycolytic acid production, and acid tolerance were performed at sub-MIC levels. Phytochemical analysis for constituents of MEP was carried out. RESULTS: MEP showed a broad antibacterial range (MIC 0.5-4 mg/ml). The MBC was two to four times higher than the MIC. The time-kill curves showed S. mutans and S. sobrinus were significantly killed after 1h of incubation. At sub-MIC levels, doubling times of S. mutans and S. sobrinus dose-dependently increased up to 211% and 123%, respectively. At sub-MIC levels, MEP also showed inhibitory effects on the virulence factors of S. mutans and S. sobrinus in a dose-dependent fashion. Phytochemical analysis revealed the presence of alkaloids, sterol/terpenes, tannins, flavonoids, and carbohydrates. CONCLUSION: These data indicate that MEP has inhibitory effects on bacterial viability at higher concentrations (> or =MIC) and the virulence factors of S. mutans and S. sobrinus at sub-MIC concentrations, suggesting that it might be useful for the control of dental plaque formation and subsequent dental caries formation.     

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.     

Susceptibility of Streptococcus mutans and Streptococcus sobrinus to cell wall inhibitors and development of a novel selective medium for S. sobrinus

Representative strains of Streptococcus mutans and Streptococcus sobrinus showed differences in susceptibility to members of the monobactam group of beta-lactam antibiotics: S. sobrinus was less sensitive than S. mutans. The minimum inhibitory concentrations of aztreonam (AZT) and carumonam, both of which belong to this group, were 2,000 microg/ml for S. sobrinus and 125 microg/ml for S. mutans. Further addition of fosfomycin, bacitracin and sodium chloride to Mitis Salivarius agar (MS) supplemented with AZT resulted in growth inhibition of S. mutans and oral streptococci other than S. sobrinus, and was therefore used as a selective medium for S. sobrinus (MS-SOB medium). The average growth recovery of laboratory and clinically isolated strains of S. sobrinus on MS-SOB medium was 74.1% compared to that on MS medium. Seventy-eight percent of clinical samples in which S. sobrinus was detected yielded pure growth of S. sobrinus on MS-SOB medium.     

酪蛋白磷酸肽钙磷复合体对变形链球菌生长的实验研究

目的：研究酪蛋白磷酸肽钙磷复合体（CPP—ACP）对变形链球菌生长的影响。方法：将变形链球菌ATCC25175（血清型c）加入实验组即含不同浓度（0．5％～5．0％。W／V）CPP-ACP溶液和对照组（不含CPP—ACP溶液）的BHI培养基中厌氧培养48h。采用噻唑蓝（MTT）比色分析法测定细菌浓度的吸光度A值（λ=550nm）。结果：随CPP—ACP浓度的升高,变形链球菌甲胎产物的二甲亚砜溶液的吸光度值降低,即变形链球菌的活菌数减少（P〈0．01）。结论：CPP—ACP对变形链球菌生长具有抑制作用。且随CPP—ACP浓度的升高抑制作用增强。     

Effect of a bacteriocin-producing strain of Streptococcus sobrinus on infection and establishment of Streptococcus mutans on tooth surfaces in rats

The effect of bacteriocin produced by Streptococcus sobrinus MT6223 on infection and establishment of Streptococcus mutans MT6222 was studied in specific pathogen-free rats. These strains were isolated from a carious lesion of a single subject. S. mutans MT6222 was found to be susceptible to the growth inhibitory action of S. sobrinus MT6223. When simultaneously inoculated into the oral cavity of rats, even a small inoculum (10(5) CFU) of S. sobrinus MT6223 completely inhibited colonization of S. mutans MT6222 on the tooth surface. Also, S. sobrinus MT6223 eliminated S. mutans MT6222 when MT6223 (10(8) CFU) was inoculated 2 days after the inoculation of 10(8) CFU cells of MT6222. Similar results were obtained in dental plaque samples from the tooth surface and the fissures of the upper molars at the end of the experiment. However, when S. sobrinus MT6223 (10(8) CFU) was inoculated 2 weeks after the inoculation of S. mutans MT6222 (10(8) CFU), MT6223 coexisted with MT6222. However, the plaque samples showed that MT6223 inhibited the establishment of MT6222 on smooth surfaces, but not in fissures. In addition, MT6223 protected against subsequent infection with MT6222. However, a nonbacteriocinogenic mutant of S. sobrinus MT6223 did not inhibit the infection and establishment of S. mutans MT6222.