姜黄素对变形链球菌和溶血链球菌黏附能力的分析研究

目的:探讨姜黄素对变形链球菌和溶血链球菌的黏附能力改变.方法:采用基因工程的方法体外制备和纯化变形链球菌和溶血链球菌的Sortase A酶,荧光记录分析的方法检测姜黄素对纯化的Sortase A酶的IC50值.微量肉汤稀释法检测姜黄素对这两种细菌的最低抑菌浓度(MIC),统计细菌计数的方法检测姜黄素对这两种细菌单菌种黏...     

杨梅黄酮对变形链球菌毒力因子及生物膜的抑制作用研究

目的:探讨杨梅黄酮对变形链球菌(Streptococcus mutans,S.mutans)ATCC 25175毒力因子和生物膜的作用.方法:用液体稀释法准确测定杨梅黄酮对变形链球菌的最小抑菌浓度(MIC)和耐酸性;用结晶紫染色法检测药物对变形链球菌生物膜形成的抑制率;用乳酸试剂盒检测药物对变形链球菌产酸的影响;用蒽酮...     

五倍子对菌斑生物膜内细菌的抑制作用

目的:应用人工口腔观察五倍子对菌斑生物膜内细菌的抑制作用。方法:采用液体二倍稀释法测定与致龋病关系较密切的4种细菌的最小抑菌浓度,并进一步在人工口腔中形成各实验菌的单一细菌菌斑生物膜,应用菌落计数技术观察五倍子水提取物对菌斑生物膜内细菌的抑制作用。结果:五倍子水提取物对变形链球菌、粘性放线菌、血链球菌、口腔链球菌的生长均有抑制作用,其中对变形链球菌、粘性放线菌和血链球菌的最小抑菌浓度(MIC)为64mg/ml,口腔链球菌为8mg/ml;不同浓度的五倍子水提取物对各实验菌形成的单一细菌菌斑生物膜均有一定的抑制作用,并呈浓度依赖性;即使采用大于MIC的浓度,也不能把釉质表面形成的生物膜完全抑制,釉质表面仍有细菌生长。结论:五倍子水提取物对菌斑生物膜内细菌具有良好的抑制作用;与浮游细菌相比,生物膜中的细菌对五倍子水提取物具有较强的抵抗力。     

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。     

薄荷复方煎液对龋病、牙周病致病菌杀菌作用的研究

目的：研究薄荷复方煎液对龋病、牙周病致病菌的抑制和杀灭作用。方法：致龋菌血链球菌、变形链球菌和牙周病致病菌牙龈卟啉单胞菌分离培养,将薄荷复方煎液配成不同浓度,分别对4种细菌做药敏试验,记录各自的最小抑菌浓度（MIC）和最小杀菌浓度（MBC）。结果：血链球菌MIC1：32,变形链球菌MIC1：4,牙龈卟啉单胞菌MIC1：32;血链球菌MBC1：16,变形链球菌MBC1：1,牙龈卟啉单胞菌MBC1：8。结论：薄荷复方煎液对龋病、牙周病致病菌有抑制和杀灭作用。     

壳寡聚糖抑制变形链球菌的致龋能力

目的研究壳寡聚糖(chitooligosaccharide,COS)对变形链球菌生长、产酸及粘附能力的影响。方法选用变形链球菌标准株ATCC 25175,采用对倍稀释法测定COS对变形链球菌的最低抑菌浓度(minimum inhibitory concentration,MIC)和最低杀菌浓度(minimum bactericidal concentration,MBC);采用菌落计数法,通过时间—杀菌曲线的变化,分析COS对细菌生长速度的影响;将COS及变形链球菌菌悬液各1 m L接种于无菌试管内厌氧培养,使COS的终浓度分别达到1/2 MIC、1/4 MIC、1/8MIC,测定上清液p H变化并绘制p H曲线;采用液体闪烁计数法测定壳寡聚糖对变形链球菌粘附羟磷灰石能力的影响。结果 COS对变形链球菌的MIC和MBC分别为2.00 g/L和4.00 g/L;COS能有效抑制变形链球菌的生长,较高浓度时对细菌还具有杀菌作用。亚抑菌浓度的COS可显著影响变形链球菌的产酸性和粘附能力,并且这种抑制作用呈浓度依赖性。结论 COS对变形链球菌的生长、产酸和粘附能力均有抑制作用。     

赤芍粗提物对变形链球菌影响的实验研究

目的研究赤芍粗提物对变形链球菌的生长、产酸、粘附及合成胞外多糖的影响。方法采用倍比稀释法测定不同浓度赤芍粗提物抑制变形链球菌生长的情况,通过统计学方法确定最低抑菌浓度（minimal inhibitory concentration,MIC）;再以MIC及低于MIC的4个倍比稀释浓度配制含药的胰酶解酪蛋白-植物蛋白胨-酵母提取物（trypticase-phytone-yeast extract medium,TPY）液体培养基,测定赤芍粗提物对变形链球菌产酸、粘附及合成胞外多糖能力的影响。结果赤芍粗提物抑制变形链球菌体外生长的MIC为12.5g/L;当赤芍粗提物浓度≥3.13g/L时有较明显地抑制变形链球菌产酸、粘附、合成水溶性胞外多糖的作用;当赤芍粗提物浓度≥6.25g/L时能明显抑制变形链球菌合成水不溶性胞外多糖。结论达到一定浓度的赤芍粗提物对变形链球菌的生长、产酸、粘附及合成胞外多糖均有一定的抑制作用。     

蜂胶对变形链球菌的抑菌及粘附抑制实验

目的：测定蜂胶对变形链球菌的抑菌及粘附抑制作用效果，以探讨蜂胶防龋的机制。方法：①用不同浓度的蜂胶溶液，采用杯碟法检测晨胶溶液抑菌活性，并测出其最小抑菌浓度；②用0.04％、0.01％蜂胶溶液采用毛细管法检测蜂胶对变形链球菌粘附抑制效果，设置空白对照及2％氟化钠阳性对照。结果：①蜂胶溶液对变形链球菌有较强的抑菌作用，最小抑菌浓度为0.025％；②0.04％、0.01％两个浓度的蜂胶溶液对变形链球菌的粘附抑制作用明显高于对照组。结论：蜂胶对变形链球菌有明显的抑菌及抑制变形链球菌粘附作用，提示蜂胶具有较强的防龋效果。     

茶黄素对变异链球菌浮游细菌和生物膜的体外抑制作用

目的:探讨茶黄素（theaflavin,TF）对变异链球菌浮游细菌和生物膜的抑制作用。方法:分别测定TF溶液、表没食子儿茶素没食子酸酯（EGCG）溶液、氯己定（CHX）溶液和乙醇对照溶液对变异链球菌UA159的最低抑菌浓度（minimum inhibitory concentration, MIC）和最低杀菌浓度（minimum bactericidal concentration, MBC）。体外构建变异链球菌UA159的生物膜,测定实验试剂对细菌增殖活性的影响及杀菌作用。采用SPSS 22.0软件包对数据进行统计学分析。结果:TF对变异链球菌UA159的MIC为500 μg/mL,MBC 为1 mg/mL。TF溶液浓度在2×MIC以上时,变异链球菌生物膜的代谢活性显著降低（P<0.05）,对生物膜也表现出较强的杀菌作用。结论:TF对已形成的变异链球菌UA159的生物膜具有显著的抑制活性以及杀菌作用,为TF的进一步临床应用提供了研究基础。     

茶多酚对口腔细菌致龋力影响的实验研究

目的：通过研究茶多酚对致龋菌生长，产酸及产胞外多糖的影响。探讨茶多酚是否能有效调节口腔菌群生态平衡，方法：测定茶多酚对三种主要致龋菌－变形链球菌，粘性放线菌和血链球菌的最低抑菌浓度（MIC），再测定低于MIC的4个浓度的茶多酚对三种细菌产酸及产生水溶性和水不溶性多糖能力的影响。结果：茶多配合酚对三种细菌的生长，产酸均有一定的抑制作用。茶多酚能够有效抑制变形链球菌产生水溶性葡聚糖，但对变形链球菌产生水溶性葡聚糖以及粘性放线菌和血链球菌合成胞外多糖无明显的抑制作用。结论：茶多酚能有效抑制变形;链球菌，粘性放射菌和血链球菌的生长，产酸及变形链球菌产生水不溶性葡聚糖。     

Curcumin reduces Streptococcus mutans biofilm formation by inhibiting sortase A activity

BackgroundSortase A is an enzyme responsible for the covalent attachment of Pac proteins to the cell wall in Streptococcus mutans. It has been shown to play a role in modulating the surface properties and the biofilm formation and influence the cariogenicity of S. mutans. Curcumin, an active ingredient of turmeric, was reported to be an inhibitor for Staphylococcus aureus sortase A. The aim of this study was to investigate the inhibitory ability of curcumin against S. mutans sortase A and the effect of curcumin for biofilm formation.MethodsThe antimicrobial activity of the curcumin to the S. mutans and inhibitory ability of the curcumin against the purified sortase A in vitro were detected. Western-blot and real-time PCR were used to analysis the sortase A mediated Pac protein changes when the S. mutans was cultured with curcumin. The curcumin on the S. mutans biofilm formation was determined by biofilm formation analysis.ResultsCurcumin can inhibit purified S. mutans sortase A with a half-maximal inhibitory concentration (IC₅₀) of (10.2 ± 0.7) μmol/l, which is lower than minimum inhibitory concentration (MIC) of 175 μmol/l. Curcumin (15 μmol/l) was found to release the Pac protein to the supernatant and reduce S. mutans biofilm formation.ConclusionsThese results indicated that curcumin is an S. mutans sortase A inhibitor and has promising anti-caries characteristics through an anti-adhesion-mediated mechanism.     

Effect of nicotine on growth and metabolism of Streptococcus mutans

Streptococcus mutans is a key contributor to dental caries. Smokers have a higher number of caries-affected teeth than do nonsmokers, but the association among tobacco, nicotine, caries, and S. mutans growth has not been investigated in detail. Seven S. mutans strains--UA159, UA130, 10449, A32-2, NG8, LM7, and OMZ175--were used in the present study. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC), planktonic cell growth, biofilm formation, metabolism, and structure (determined using scanning electron microscopy) of the seven strains treated with different concentrations of nicotine (0-32 mg ml(-1)) were investigated. The MIC, MBC, and MBIC were 16 mg ml(-1) (0.1 M), 32 mg ml(-1) (0.2 M), and 16 mg ml(-1) (0.1 M), respectively, for most of the S. mutans strains. Growth of planktonic S. mutans cells was significantly repressed by 2.0-8.0 mg ml(-1) of nicotine. Biofilm formation and metabolic activity of S. mutans was increased in a nicotine-dependent manner up to 16.0 mg ml(-1) of nicotine. Scanning electron microscopy revealed that S. mutans treated with a high concentration of nicotine a had thicker biofilm and more spherical bacterial cells. In summary, nicotine enhances S. mutans biofilm formation and biofilm metabolic activity. These results suggest that smoking can increase the development of caries by fostering increased formation of S. mutans biofilm on tooth surfaces.     

不同pH对变异链球菌体外生物膜形成的影响

目的：了解变异链球菌临床株体外生物膜形成规律以及不同pH对生物膜形成的影响。方法：采用微孔板培养,染色、分光光度测定法（A630）绘制体外不同pH条件下（pH=7.0～5.0）593号、18号菌株以及变异链球菌标准株（ATCC25175）的生物膜生长曲线。结果：体外变异链球菌各株在pH=5.0时均不能形成生物膜;pH=7.0时细菌生物膜形成表现为缓慢的非线性生长,12～24h生物膜开始成熟,24～36h出现一相对的生长停滞期;pH=5.0时对已形成12h的变链菌生物膜生长有明显的抑制作用,但经历12h的酸休克后各菌株的生物膜均能恢复生长。结论：变异链球菌在体外pH=7.0时于12～24h形成稳定的生物膜,该生物膜能抵抗一定程度的酸（pH=5.0）攻击,而浮游状态的细菌则不能。     

甘草水煎剂对变异链球菌生长和产酸影响的体外研究

目的研究甘草水煎剂对体外培养的变异链球菌的抗菌活性。方法取粒径为0.2～3.2 mm的甘草颗粒加去离子水煎煮后过滤,滤液为实验用甘草水煎剂。采用液体稀释法测定甘草水煎剂对变异链球菌的最低抑菌浓度（MIC）和最低杀菌浓度（MBC）。在不同浓度甘草水煎剂中培养变异链球菌,分别于培养0﹑3﹑7﹑12﹑23、40 h时测定细菌悬液光密度值和培养液pH值,绘制变异链球菌的生长曲线和产酸曲线。结果甘草水煎剂对变异链球菌的MIC为50 mg·mL-1,浓度小于等于100 mg·mL-1的甘草水煎剂对变异链球菌无杀菌作用。甘草水煎剂对变异链球菌生长的抑制作用随浓度的增加而增强。甘草水煎剂对变异链球菌的产酸有一定的抑制作用,在培养12 h时抑制作用最强。结论甘草水煎剂对体外培养的变异链球菌生长和产酸均有抑制作用。     

载银氧化石墨烯对变异链球菌生长及生物膜形成的影响

目的探讨载银氧化石墨烯（GO/Ag）纳米复合物对变异链球菌（S.mutans）生长及生物膜形成的抑制作用。 方法应用梯度稀释法检测GO/Ag、氧化石墨烯（GO）、纳米银（AgNPs）对变异链球菌的最小抑菌浓度（MIC）;菌落形成单位计数法比较GO/Ag、GO、AgNPs对变异链球菌的抑制作用;采用结晶紫染色法和XTT法测定变异链球菌24 h生物膜的生成量和活性;激光共聚焦扫描显微镜（CLSM）观察生物膜形态和计算24 h生物膜的活菌比例。数据以单因素方差分析（One-Way ANOVA）和LSD-t检验进行统计分析。 结果GO/Ag对变异链球菌的MIC为0.16 mg/mL。0.64 mg/mL GO/Ag对变异链球菌的抑菌率为（82.90 ± 4.87）%,与对照组间的差异有统计学意义（t= 30.804,P<0.001）。而GO和AgNPs材料浓度提升至2.56 mg/mL时,肉眼观察细菌仍未见明显减少。在0.16 mg/mL GO/Ag浓度下,变异链球菌生物膜生成量和活性的减少率分别为（25.12 ± 0.01）%和（38.90 ± 3.42）%,活菌比例为（42.76 ± 19.48）%,与空白对照组间的差异均有统计学意义（t_生成量= 7.274,P_生成量<0.001;t_活性= 7.765,P_活性<0.001;t_活菌比例= 10.412,P_活菌比例<0.001）。 结论与AgNPs和GO相比,GO/Ag新型纳米复合物对变异链球菌的生长具有较好的抑制作用,并能抑制其生物膜形成。     

变异链球菌luxS基因对牙菌斑生物膜形成的影响研究

目的敲除变异链球菌中的luxS基因,构建luxS突变株,测试变异链球菌失去luxS基因后形成牙菌斑生物膜的能力。方法把luxS基因敲除重组质粒转入变异链球菌UA159中,得到转化菌,在含有卡拉霉素的培养基中进行筛选,得到变异链球菌luxS基因突变株,并利用聚合酶链式反应（PCR）和哈氏弧菌发光实验对变异链球菌luxS突变株进行检测,通过扫描电镜,对不同时间段变异链球菌luxS突变株和变异链球菌UA159在BHIS培养液（含1%蔗糖的脑心浸液）和BHIG培养液（含1%葡萄糖的脑心浸液）中形成的生物膜进行比较。结果成功的构建了变异链球菌luxS突变株,在BHIS培养液中,变异链球菌luxS突变株形成生物膜的能力比变异链球菌UA159弱,而在BHIG培养液中,二者无显著差异。结论变异链球菌luxS基因对牙菌斑生物膜的形成有重要的影响,并且luxS基因对变异链球菌生物膜的调控是蔗糖依赖型的。     

呋喃C-30对变异链球菌生物膜早期形成的影响

目的：探讨密度感应拮抗剂呋喃C-30对变异链球菌生物膜早期形成的影响。方法：将体外合成的密度感应拮抗剂呋喃C-30按终浓度10、100μmol/L分别配制于含变异链球菌的牛心脑浸液培养基,37℃微需氧培养24h,形成生物膜后,用生物膜定量分析仪检测生物膜形成的量。结果：100μmol/L呋喃C-30组变异链球菌生物膜的形成受到显著抑制,磁珠成像开始减弱和完全消失的时间均迟于对照组;生物膜开始形成后,其生物膜形成指数低于对照组,差异有统计学意义（P〈0.05）。结论：呋喃C-30在100μmol/L浓度时能有效抑制变异链球菌生物膜的形成,其应用可能为龋病防治提供新的思路。     

Antibacterial Activity of Curcumin Against Periodontopathic Bacteria

Background: Curcumin is a polyphenol extracted from root of turmeric and known to possess multifunctional properties, including antibacterial activity. Although previous studies have investigated the effects of curcumin on microorganisms, available knowledge on the effects of curcumin on periodontopathic bacteria is still limited. In this study, the antibacterial effect of curcumin on periodontopathic bacteria is investigated, particularly Porphyromonas gingivalis. Methods: Representative periodontopathic bacteria were cultured in media with and without various curcumin concentrations, and the optical density at 600 nm was measured for 60 hours. The inhibitory effect of curcumin on P. gingivalis Arg‐ and Lys‐specific proteinase (RGP and KGP, respectively) activities were assessed using spectrofluorophotometric assay. Analysis of biofilm formation by P. gingivalis with or without Streptococcus gordonii was conducted using confocal laser‐scanning microscopy (CLSM). Results: Curcumin inhibited the growth of P. gingivalis, Prevotella intermedia, Fusobacterium nucleatum, and Treponema denticola in a dose‐dependent manner. Bacterial growth was suppressed almost completely at very low concentrations of curcumin. Conversely, 100 μg/mL curcumin did not suppress the growth of Aggregatibacter actinomycetemcomitans. It also demonstrated inhibitory effects against RGP and KGP activities in a dose‐dependent manner. CLSM revealed that curcumin suppressed P. gingivalis homotypic and P. gingivalis–S. gordonii heterotypic biofilm formation in a dose‐dependent manner. A concentration of 20 μg/mL curcumin inhibited these P. gingivalis biofilm formations by >80%. Conclusion: Curcumin possesses antibacterial activity against periodontopathic bacteria and may be a potent agent for preventing periodontal diseases.     

The effect of cocoa polyphenols on the growth, metabolism, and biofilm formation by Streptococcus mutans and Streptococcus sanguinis

The aim of this study was to determine if cocoa polyphenols could interfere with biofilm formation by Streptococcus mutans or Streptococcus sanguinis, and reduce acid production from sucrose by S. mutans. The antimicrobial activity of cocoa polyphenols was assessed against cariogenic (S. mutans) and health-associated (S. sanguinis) species by minimum inhibitory concentration assays. Cocoa polyphenol dimer, tetramer, and pentamer inhibited the growth of S. sanguinis, whereas the growth of S. mutans was unaffected. However, pretreatment of surfaces with cocoa polyphenol pentamer (35 microM) reduced biofilm formation by S. mutans at 4 and 24 h, whereas the effects on S. sanguinis were less consistent. In contrast, brief exposure of preformed biofilms to pentamer either had no significant effect or resulted in increased counts of S. mutans under certain conditions. Cocoa polyphenol pentamer (500 microM) significantly reduced the terminal pH, and inhibited the rate of acid production by S. mutans at pH 7.0. In conclusion, cocoa polyphenols can reduce biofilm formation by S. mutans and S. sanguinis, and inhibit acid production by S. mutans.     

没食子鞣质和联合氟化钠对不同状态变链菌葡萄糖基转移酶活性的影响

目的：实验采用析因设计方法研究天然维药没食子和没食子联合氟化钠对变形链球菌浮游及生物膜状态下葡萄糖基转移酶（GTF）活性的影响,探讨实验药物防龋的作用机制。方法：用脑心浸液液体培养基分别培养浮游和生物膜状态下的变形链球菌,根据析因实验的分组将配置好的没食子鞣质、氟化钠、没食子鞣质联合氟化钠加入相应的菌液中厌氧培养18h。硫酸铵沉淀法提取粗酶,考马斯亮蓝法和蒽酮法分别测定总蛋白和还原糖含量,计算酶活性和药物对酶活性的抑制率。实验结果采用SPSS17．0软件包进行数据分析。结果：GTF酶活性在细菌不同培养状态下有统计学意义（P〈0．05）,浮游状态下GTF酶活性高于生物膜状态;没食子、氟化钠、没食子联合氟化钠对细菌不同状态下GTF酶活性的抑制率有差异（P〈0．05）,浮游状态下的葡萄糖基转移酶比生物膜状态对药物作用敏感,没食子的抑制作用最为显著。抑制率没食子〉没食子联合氟化钠〉氟化钠。结论：没食子鞣质可能是通过抑制葡萄糖基转移酶活性抑制变形链球菌的粘附,从而达到防龋的作用。