口腔常见致病菌的表面疏水性分析

目的：分析测试几种口腔常见致病菌的细胞表面疏水性，为研究细菌非特异性黏附机制提供科学理论参数。方法：采用碳氢化合物黏着法测试细菌表面疏水性。结果：不同种类的细菌、同种细菌的不同菌株间疏水性均存在差异。每株细菌表面具有其相对稳定的参考值范围。结论：口腔细菌具有强弱不同的疏水作用。     

口腔细菌黏附机制的研究进展

口腔细菌黏附的机制是口腔微生物学和生态学的研究热点之一,近年来,随着分子生物研究水平的提高,口腔细菌黏附机制的研究在分子水平上有了较大的进展.细菌表面的黏附蛋白和受体以及菌毛和胞外多糖都参与细菌间的共聚及细菌对牙表面的黏附.材料表面的获得性薄膜、粗糙度、表面电荷和疏水性等特性也能影响细菌的定植和黏附.本文就细菌和材料两个方面对口腔细菌黏附的机制及控制细菌黏附的方法作一综述.     

伴放线放线杆菌形态变化对菌体表面疏水性影响的研究

目的研究伴放线放线杆菌形态变化对菌体表面疏水性的影响。方法采用碳氢化合物法检测伴放线放线杆菌粗糙型和光滑型的菌体表面疏水性,观察同一菌株不同表型疏水性的变化。结果伴放线放线杆菌粗糙型和光滑型菌体表面具有疏水性。14株粗糙型伴放线放线杆菌菌体表面疏水率高于4株光滑型,差异有统计学意义（P〈0．05）。4株同源的粗糙型与其光滑型转变株比较得出除1株外,其余3株菌两种表型的菌体表面疏水率差异无统计学意义（P〉0．05）。结论伴放线放线杆菌形态变化可引起菌体表面疏水性的改变,粗糙型转变为光滑型后菌体表面疏水性减弱。     

白色假丝酵母菌与龋病的相关性研究

龋病是人类最常见的感染性疾病之一。从生态学角度看,龋病是由于口腔生态平衡失调,正常菌群成为条件致病菌所致。白色假丝酵母菌是寄生于口腔内的一种酵母样真菌,具有致龋菌的生理特征:能与其他细菌共聚黏附于牙面并具有很强的产酸性和耐酸性。笔者综述这方面的研究,以期为龋病防治提供新的思路。     

柠檬精油、柠檬烯、茶多酚对变形链球菌表面疏水性及黏附的影响

目的：研究天然植物成分柠檬精油（LEO）、柠檬烯（LIM）及茶多酚（TP）对变形链球菌（S．mutans）细菌表面疏水性及黏附能力的影响。方法：取最小抑菌浓度（MIC）以下浓度作为实验浓度;采用微生物黏着碳氢化合物法（MATH）,测定 S．mu-tans 表面疏水性;采用96孔板结晶紫染色法,评价 S．mutans 的黏附。结果：LEO、LIM、TP 在低于最小抑菌浓度（MIC）时,对S．mutans 表面疏水性及粘附具有抑制作用;在一定范围内其抑制作用随浓度增大而逐渐增加（P ＜0．05）;1／2 MIC 和1／20 MIC 时 LEO 抑制表面疏水性的作用强于 LIM和 TP（P ＜0．05）。结论：LEO 具有防龋应用前景。     

纵向研究婴幼儿乳杆菌的检出情况及其与龋病的关系

目的 探讨8～32个月婴幼儿牙菌斑中乳杆菌的检出情况,了解乳杆菌与龋病的关系.方法 基线募集广州市花都区新华镇225名8个月龄婴幼儿.对其进行龋病检查和牙菌斑样本收集,之后每6个月重复1次至32个月龄.采用Bogosa选择性培养基作乳杆菌的分离培养并鉴定.χ2检验比较不同性别、年龄和不同患龋状况婴幼儿乳杆菌检出情况.结果 8、14、20、26和32个月龄婴幼儿乳杆菌检出率分别为12.0%、5.6%、11.0%、9.3%和21.3%,32个月龄乳杆菌检出率高于14和26个月龄,各年龄组中男女童乳杆菌的检出率无差别.乳杆菌阳性个体在5次样本检测中,72.3%仅为1次阳性.各年龄组患龋婴幼儿乳杆菌检出率均显著高于无龋组.结论 婴幼儿口腔中乳杆菌检出较早,但在牙面定植不稳定,随年龄的增长和龋病患病的变化而变化.     

含精氨酸的抗敏抛光膏对暴露牙本质表面变异链球菌黏附的影响

目的 研究含精氨酸抗敏抛光膏对暴露牙本质表面变异链球菌黏附的影响。方法 暴露牙本质小管,使用浮石粉和抗敏抛光膏处理表面,观察其粗糙度的变化。体外培养变异链球菌,观察其在牙本质片表面黏附及葡糖基转移酶（GTFs）基因表达情况。结果 使用浮石粉及抗敏抛光膏均能有效降低表面粗糙度,抗敏抛光膏处理后的牙本质能明显抑制gtfB和gtfC基因的表达。结论 含精氨酸抗敏抛光膏能抑制变异链球菌黏附及gtfB和gtfC基因的表达,对敏感牙本质区域龋病发生具有一定防治作用。     

乳杆菌和变链菌的牙本质粘附能力实验

目的：检测乳杆菌对牙本质的粘附能力,以探讨乳杆菌在牙本质龋中的作用。方法：利用同位素闪烁计数法测定乳杆菌和变链菌对牙本质及在磷灰石的粘附率。结果：乳杆菌对牙本质具粘附作用,对羟基磷灰石无粘附作用;变链菌对牙本质和羟基磷灰石均具粘附作用。结论：乳杆菌因其对牙本质具有较强粘附作用,且产酸能力强,可引起牙本质脱矿,在牙本质龋进展中发挥重要作用。     

乙醇润湿在牙本质疏水性粘接的应用研究

目的：研究乙醇润湿技术应用于牙本质疏水性粘接的效果。方法：20颗无龋第三磨牙去除冠部釉质后,随机分成4组。实验组用无水乙醇润湿牙面30s或用梯度乙醇润湿牙面后进行疏水性粘接;阳性对照组采用AdperScotchbond Multi-Purpose粘接;阴性对照组在水润湿的牙面进行疏水性粘接。固化24h后进行微拉伸粘接强度检测和扫描电镜观察。结果：梯度乙醇润湿组的粘接强度和阳性对照组相比无显著性差异,所形成的混合层均匀致密,树脂突较多;而乙醇润湿30s组的粘接强度低于对照组（P〈0.05）,其混合层不均匀,树脂突短而少。结论：在牙本质疏水性粘接中使用梯度乙醇润湿的方法可获得良好的粘接效果。     

龋病相关细菌的细菌素

细菌素是由某些细菌在代谢过程中通过核糖体合成机制产生的一类具有生物活性的蛋白质、多肽或前体多肽.龋病相关细菌产生的细菌素可能与细菌的定植、黏附等致龋性有关.本文介绍龋病相关细菌产生的细菌素,重点介绍变链素、乳杆菌素和血链素等的研究进展.     

Surface properties of lactobacilli isolated from healthy subjects

OBJECTIVE: Lactobacilli are considered cariogenic micro-organisms. As oral species of lactobacilli have not been thoroughly described, the aim of this work was to isolated and identify these organisms from teeth, tongue, saliva and gum of healthy patients and to describe some of their surface properties. SUBJECTS: Forty-four subjects from Tucumán, Argentina, with D, d and M, m indices equal to 0. MATERIALS AND METHODS: Samples were obtained from different areas of the oral cavity. Microorganisms were cultured in lactobacilli selected media (LBS) and identified morphologically and biochemically. Hydrophobicity was analysed by partition in organic solvents, acidity by affinity with chloroform and basicity with ethyl acetate (MATH method), aggregation and coaggregation in presence of (NH4)2SO4, and haemagglutination with ABO erythrocytes in microplates. RESULTS: Eighty-five lactobacilli were isolated; 29.4% were homofermenter, 44.7% facultative heterofermenter and 25.9% obligate heterofermenter. Predominant species were L. fermentum, L. plantarum, L. salivarius, and L. rhamnosus. Most of the strains showed moderate to high hydrophobicity and demonstrated high acid and basic surface charges with almost 40% showing salt aggregation. Few strains haemagglutinated. CONCLUSIONS: A variety of Lactobacillus species were isolated from healthy mouths, some of whom showed adhesion-related properties such as high hydrophobicity and charged surfaces. Probable mechanisms related to the ecological behaviour of lactobacilli in the oral cavity are discussed.     

Lactobacillus plantarum for oral peptide delivery

AIMS: To evaluate strains of lactobacilli for their ability to persist and secrete heterologous protein in the oral cavity. METHODS AND RESULTS: Four different strains of common oral lactobacilli, Lactobacillus brevis, Lactobacillus johnsonii, Lactobacillus murinus and Lactobacillus plantarum, were transformed with the plasmid pKTH2121, which contains a secretion cassette for beta-lactamase. Lactobacilli isolated from the mouth of host mice were also transformed with pKTH2121 for later feeding. Lactococcus lactis, transformed with pKTH2121, was also fed to mice as a negative control. All transformed isolates were fed to C57Black mice in varying schedules. The number of transformed bacteria persisting in the mouth was reported as a percentage of total oral bacteria recovered by swabbing. CONCLUSIONS: The transformed L. lactis, L. brevis, L. johnsonii, L. murinus, and the endogenous murine lactobacillus strain failed to persist in the mouth. Transformed L. plantarum, however, persisted in the mouth and comprised up to 25% of the total lactobacilli at 18 h and 10% at 24 h after feeding. L. plantarum recovered after feeding retained its ability to secrete beta-lactamase into culture medium efficiently. Beta-lactamase activity could be detected in oral secretions at 8 h after feedings. After repeated feedings, however, the L. plantarum containing pKTH2121 gradually lost its ability to persist after feedings. This experiment demonstrates that L. plantarum can transiently colonize the oral mucosa in large numbers, while continuously secreting foreign proteins, raising the possibility of using lactobacilli as a vector for delivery of oral mucosal peptides.     

Molecular and biochemical characterizations of human oral lactobacilli as putative probiotic candidates

INTRODUCTION: The objective of this study was to characterize the lactobacilli from the human oral cavity as a potential source of probiotic strains. METHODS: Samples were collected from four different locations within the oral cavity: surface of healthy tooth, oral mucous membrane, surface of tooth decay and deep tooth decay. On the basis of morphological and biochemical properties eight categories were formed and 26 isolates were selected for further characterization. The isolates were determined as Lactobacillus sp. using primers specific for 16S rDNA. Sequencing of 16S rDNA genes and repetitive sequence-based polymerase chain reactions were used for determination to species and subspecies levels. RESULTS: Predominant species were Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus salivarius and Lactobacillus paracasei subsp. paracasei, while Lactobacillus acidophilus, Lactobacillus cellobiosus, Lactobacillus delbrueckii subsp. lactis and Lactobacillus gasseri were also present. The isolates Lactobacillus salivarius BGHO1, Lactobacillus fermentum BGHO36 and BGHO64, Lactobacillus gasseri BGHO89 and Lactobacillus delbrueckii subsp. lactis BGHO99 exhibited antagonistic action on the growth of Staphylococcus aureus, Enterococcus faecalis, Micrococcus flavus, Salmonella enteritidis, Streptococcus pneumoniae and Streptococcus mutans, but not on growth of Candida albicans. Moreover, the isolates L. salivarius BGHO1 and L. gasseri BGHO89 were tolerant to low pH and high concentration of bile salts. CONCLUSION: Taken together, these findings imply that L. salivarius BGHO1 and L. gasseri BGHO89 might be subjects for additional investigation as potential probiotic strains.     

Oral and intestinal microflora in 5-fluorouracil treated rats,translocation to cervical and mesenteric lymph nodes and effects of probiotic bacteria

Serious systemic infections may occur during cancer chemotherapy due to disturbances in the oropharyngeal and gastrointestinal microflora, impaired mucosal barrier functions and immunosuppression. Bacteria may spread from the gastrointestinal tract to the regional lymph nodes. The routes for bacterial spread from the oral cavity are less well known. In the present study we investigated changes in the oral and intestinal microfloras in rats given 50 mg/kg 5-fluorouracil (5-FU) i.v. for 6 days. Bacterial dissemination to the lymph nodes draining the oral cavity and the lymph nodes draining the gastrointestinal tract was examined. Effects of adding the probiotic strain Lactobacillus plantarum 299v in the drinking water to the rats were measured. 5-FU treatment caused an increase in the number of facultative and strictly anaerobic bacteria in biopsies from the oral cavity and an increase in the number of facultative anaerobes in the large intestine. The proportion of facultative gram-negative rods increased in both the oral cavity and intestine. Bacteria translocated to both the cervical and mesenteric lymph nodes in untreated animals and increased in numbers after 5-FU treatment due to an increase in the number of facultative gram-negative rods. Treatment with L. plantarum 299v improved food intake and body weight in 5-FU-treated rats. It also reduced the 5-FU-induced raise in the total numbers of facultative anaerobes in the intestine, but did not reduce translocation and did not prevent diarrhea. This study reinforces the oral cavity, along with the gastrointestinal tract, as a source for bacterial dissemination. The use of probiotic bacteria may reduce some side effects of 5-FU treatment.     

Biofilm formation by antagonistic strains of oral Lactobacillus

Highantagonistic strains of lactobacillus isolated from the oral cavity of healthy people, genetically identified as L. fermentum 39, L. rhamnosus 50, L. rhamnosus 24, showed high degree of autoaggregation, surface hydrophobicity, coaggregation, adhesion, and the ability to form biofilms. These strains can be used to create new probiotic drugs for the prevention and correction the dysbiosis of the oral cavity.     

Characterization of oral lactobacilli as potential probiotics for oral health

INTRODUCTION: Intestinal lactobacilli have been successfully used as probiotics to treat gastrointestinal disorders, but only limited data are available for the probiotic properties of oral lactobacilli to combat oral diseases. We aimed to characterize oral lactobacilli for their potential probiotic properties according to the international guidelines for the evaluation of probiotics, and to select potential probiotic strains for oral health. METHODS: The study included 67 salivary and subgingival lactobacilli of 10 species, isolated from healthy humans. All strains were identified using amplified ribosomal DNA restriction analysis, tested for antimicrobial activity against oral pathogens, tolerance of low pH and bile content. Thereafter, the lysozyme tolerance and antibiotic susceptibility of 22 potential probiotic strains were assessed. RESULTS: The majority of strains suppressed the growth of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Streptococcus mutans, but none inhibited Candida albicans. The lowest pH tolerated by lactobacilli following 4 h of incubation was pH 2.5, but none of the strains grew at this pH. All strains tolerated a high concentration of lysozyme (10 mg/ml) and half of the strains tolerated a high concentration of human bile [5% volume/volume (V/V)]. Four Lactobacillus plantarum and two Lactobacillus oris strains expressed resistance to tetracycline and/or doxycycline. CONCLUSIONS: Strains of L. plantarum, Lactobacillus paracasei, Lactobacillus salivarius, and Lactobacillus rhamnosus expressed both high antimicrobial activity and high tolerance of environmental stress. The absence of transferable antibiotic-resistance genes in L. plantarum strains remains to be confirmed. These results suggest a potential for oral lactobacilli to be used as probiotics for oral health.     

Inhibitory effects of cranberry juice on attachment of oral streptococci and biofilm formation

Cranberry juice is known to inhibit bacterial adhesion. We examined the inhibitory effect of cranberry juice on the adhesion of oral streptococci strains labeled with [3H]-thymidine to saliva-coated hydroxyapatite beads (s-HA). When the bacterial cells were momentarily exposed to cranberry juice, their adherence to s-HA decreased significantly compared with the control (P < 0.01). Their hydrophobicity also decreased dependently with the concentration of cranberry juice. We also evaluated the inhibitory effect of cranberry juice on biofilm formation. By using a microplate system, we found that the high molecular mass constituents of cranberry juice inhibited the biofilm formation of the tested streptococci. The inhibitory activity was related to the reduction of the hydrophobicity. The present findings suggest that cranberry juice component(s) can inhibit colonization by oral streptococci to the tooth surface and can thus slow development of dental plaque.     

The influence of surface roughness and surface-free energy on supra- and subgingival plaque formation in man

Abstract In the oral cavity, an open growth system, bacterial adhesion to the non-shedding surfaces is for most bacteria the only way to survive. This adhesion occurs in 4 phases: the transport of the bacterium to the surface, the initial adhesion with a reversible and irreversible stage, the attachment by specific interactions, and finally the colonization in order to form a biofilm. Different hard surfaces are available in the oral cavity (teeth, filling materials, dental implants, or prostheses), all with different surface characteristics. In a healthy situation, a dynamic equilibrium exists on these surfaces between the forces of retention and those of removal. However, an increased bacterial accumulation often results in a shift toward disease. 2 mechanisms favour the retention of dental plaque: adhesion and stagnation. The aim of this review is to examine the influence of the surface roughness and the surface free energy in the adhesion process. Both in vitro and in vivo studies underline the importance of both variables in supragingival plaque formation. Rough surfaces will promote plaque formation and maturation, and high-energy surfaces are known to collect more plaque, to bind the plaque more strongly and to select specific bacteria. Although both variables interact with each other, the influence of surface roughness overrules that of the surface free energy. For the subgingival environment, with more facilities for microorganisms to survive, the importance of surface characteristics dramatically decreases. However, the influence of surface roughness and surface-free energy on supragingival plaque justifies the demand for smooth surfaces with a low surface-free energy in order to minimise plaque formation, thereby reducing the occurrence of caries and periodontitis.     

3种植物提取物联用对变形链球菌致龋力的影响

目的:探究绿茶、野菊花、薄荷提取物及其混合物对变形链球菌增殖、产酸及粘附能力的影响。方法:变形链球菌在含有不同浓度植物提取物的MS培养基中培养24 h后,进行离心,清洗,将菌细胞混悬于一定体积蒸馏水中,分光光度计测出A值。使用pH仪测定离心后上清液pH值。玻片粘附法观察提取物对变形链球菌粘附能力的影响。结果:各浓度的提取物及其混合物对变形链球菌增殖、产酸、粘附均有抑制作用(P＜0.05)。浓度为24 g/L时,绿茶较其他提取物抑制变形链球菌增殖能力强(P＜0.01)。浓度为0.75 g/L、1.5 g/L、3 g/L时,混合物抑制变形链球菌粘附能力较同浓度其他提取物强(P＜0.05)。结论:3种植物提取物均具有一定防龋能力,在抑制变形链球菌粘附能力方面三者可协同发挥作用。     

Inhibition of adherence of Candida albicans and Candida dubliniensis to a resin composite restorative dental material by salivary secretory IgA and monoclonal antibodies

OBJECTIVE: The attachment of Candida to oral surfaces is a crucial step in the colonization of the oral cavity and the eventual development of oral diseases caused by this microorganism. Inhibition of adhesion is one of the strategies currently studied to prevent Candida infections. The main objective of this study was to investigate the inhibitory effect of the human salivary components on the adherence of Candida albicans and C. dubliniensis to Herculite, a widely used resin composite restorative dental material. We have also investigated the influence on the adherence of three monoclonal antibodies (mAbs) directed against C. albicans cell wall antigens. DESIGN: The adhesion of three strains of C. albicans and one strain of C. dubliniensis was studied by a visual method after incubating the fungus and the resin in presence and in absence of human whole saliva, secretory immunoglobulin A (sIgA) and three mAbs directed against C. albicans cell wall surface antigens. RESULTS: Adherence of C. albicans was inhibited by whole saliva (41.7%), salivary sIgA (55.7%) and the salivary components that bind to the cell wall (36.7%). Whole saliva significantly reduced the adhesion of C. dubliniensis to Herculite to 45.3% of the control level. Saliva previously adsorbed with fungal cells or sIgA depleted saliva had no effect on adherence. An inhibition in the adhesion of C. albicans and C. dubliniensis to Herculite similar to that shown by whole saliva was also observed when mAbs C7 and 26G7 were used. However, mAb 21E6 increased adhesion of all the strains to Herculite. CONCLUSIONS: The results suggest that sIgA, as well as whole saliva, are important in blocking adherence of C. albicans and C. dubliniensis to Herculite and that this effect can be reproduced with mAbs directed against the cell wall surface of C. albicans.