口腔中生物膜分散机制的研究进展

细菌生物膜是细菌在介质表面黏附生存的细菌群体,生物膜菌落的形成使得细菌更容易适应周围环境。在生物膜发展的最后一个阶段,细菌从生物膜菌落中分离出来然后分散到周围环境中,这个过程称为生物膜的分散。生物膜分散由酶促降解、种植传播、鼠李糖脂的产生等机制介导,并受到自身以及外界多种物理化学因素等调控。口腔中生物膜分散一方面使细菌得以从病灶扩散到新的部位导致感染性疾病的加重,而另一方面,分散开的细菌由于失去生物膜的保护而变得容易去除和杀灭。通过对生物膜分散机制的研究,找到促进生物膜分散的途径,解决治疗难治性细菌感染的难题,是近年来的研究热点。本文就生物膜形成发展、分散机制、调控和临床意义做一综述。     

牙菌斑

牙菌斑是一种细菌性生物膜，为基质包裹的互相黏附，或黏附于牙面、牙间或修复体表面的软而未矿化的细菌性群体，不能被水冲去或漱掉。牙菌斑生物膜是整体生存的微生物生态群体，不同于悬浮的单个细菌，细菌凭借生物膜的独特结构黏附在一起生长，使细菌附着很紧，难以清除；另外，菌斑生物膜的形成是一种适应过程，使细菌能抵抗宿主防御功能、     

D-氨基酸对细菌生物膜分散作用的研究进展

细菌是导致感染性疾病的主要来源,细菌分泌的胞外多糖等物质聚集可形成致密的生物膜,使抗生素难以对其发挥杀菌作用,甚至可产生耐药性。细菌生物膜的存在给临床治疗增加了难度。口腔牙菌斑生物膜是龋病发生发展的始动因素,因此,有效清除和控制牙菌斑生物膜是防治龋病的关键。D-氨基酸作为细菌生物膜信号分子,能促进生物膜分散,进而促进抗菌药物发挥杀菌作用。文章就D-氨基酸对细菌生物膜分散作用的研究进展做一综述,为临床上清除牙菌斑生物膜的治疗方案提供新的思路。     

口腔修复材料界面对菌斑生物膜的影响

随着口腔医学的发展,各种口腔修复材料被广泛应用于临床治疗中。修复材料不同的表面结构及化学性质会对细菌的黏附定植以及生物膜的发育成熟产生一定的影响。在唾液环境中,虽然获得性膜可在一定程度上弱化不同材料界面的固有特性,但材料界面的某些特性仍能通过远程作用力穿透获得性膜并作用于微生物的初始黏附,从而影响生物膜的发生发展。在生物黏附早期,材料界面主要通过各种力学因素从而对微生物黏附产生影响。此外,修复材料还可通过化学物质的释放来影响生物膜的代谢。复合树脂、玻璃离子黏固剂、陶瓷材料和金属材料是口腔常见的修复材料,探讨常见口腔材料界面对生物膜的影响机制,可为口腔材料的改性研发提供理论支持。     

格氏链球菌表面黏附蛋白的研究进展

格氏链球菌细胞表面含有多种黏附蛋白,使细菌较容易的黏附在宿主牙齿和黏膜等组织表面,从而使格氏链球菌成为牙菌斑生物膜初始形成时起重要作用的一类细菌,与龋病和牙周病等口腔常见疾病的发生密切相关。本文就目前研究较多的格氏链球菌表面黏附蛋白的结构及其与宿主和其他微生物之间的关系作一综述。     

牙菌斑生物膜的研究进展

牙菌斑生物膜是龋病和牙周病的始动因子。作为典型的细菌性生物膜^[1]，由链球菌属、乳杆菌属、放线菌属及其他菌属微生物细胞和细胞外多糖基质组成，各种细菌存在于宿主和细菌胞外多聚物基质包绕的立体三维结构中^[2]，相互黏附或附着、定植于牙表面及界面。经过动态的发展循环过程，     

白假丝酵母菌与龋病的相关性及其致龋机制

白假丝酵母菌是一种革兰阳性真菌微生物,广泛存在于健康人的上呼吸道、肠道和阴道中,当其与宿主处于共生状态时不会引起疾病,反之则由酵母相转化为菌丝相,导致口腔黏膜感染,引起口腔龋坏病变。在龋病患者的口腔生物膜上,变异链球菌和白假丝酵母菌之间可能存在某种互动关系并介导龋病的发展。白假丝酵母菌可与格氏链球菌紧密地黏附在一起,即格氏链球菌细胞壁表面的多糖是白假丝酵母菌黏附的受体之一。格氏链球菌可缓解群体感应机制对白假丝酵母菌菌丝相形成和生物膜生长的抑制作用,从而增加菌斑生物膜的量。本文就白假丝酵母菌,白假丝酵母菌与龋病的相关性,白假丝酵母菌与变异链球菌、格氏链球菌和其他口腔细菌相互作用参与龋病的发生发展的可能机制等研究进展作一综述,旨在为以后的临床研究提供思路和参考。     

信号传导在口腔细菌特异性黏附中的引导作用

黏附是细菌定居和致病的基础。在黏附过程中,存在着复杂的细菌与获得性膜以及细菌与细菌之间的信号传导。下面就细菌黏附机制、口腔细菌信号传导的类型以及信号传导在口腔细菌黏附中的作用等初步探讨信号传导与口腔细菌特异性黏附之间的关系,为控制口腔细菌生物膜的形成提供一种新的思路。     

口腔微生物的附着

口腔是复杂的生态环境。由于口腔的温度及湿度适宜,营养供给丰富,氧化还原电位的差异,因此适合各类微生物生长。口腔微生物种类繁多,这些微生物能以惊人的选择性方式附着于牙面和口腔粘膜表面。下表可以说明一些主要口腔细菌在口腔中的附着部位,以及与实验观察结果进行比较的情况。     

多胺对细菌生物膜作用的多样性

生物膜的形成和分散受多种因素调控,阻断生物膜的形成及促进生物膜的解离分散是目前的研究热点和前沿方向。近年来的研究表明,多胺这一在原核和真核生物中广泛存在的物质同样在细菌生物膜的形成和分散过程中起到了非常重要的作用,本文就多胺对细菌生物膜相关作用的研究作一综述。     

Biofilms of the oral cavity. Formation,development and involvement in the onset of diseases related to bacterial plaque increase

Biofilm is defined as a community of bacteria intimately associated with each other and included within an exopolymer matrix: this biological unit exhibits its own properties, quite different in comparison with those showed by the single species in planktonic form. The oral cavity appears as an open ecosystem, with a dynamic balance between the entrance of microrganisms, colonisation modalities and host defences aimed to their removal: to avoid elimination, bacteria need to adhere to either hard dental surfaces or epithelial surfaces. The oral biofilm formation and development, and the inside selection of specific microrganisms have been correlated with the most common oral pathologies, such as dental caries, periodontal disease and peri-implantitis. Many of these bacteria are usual saprophytes of the oral environment, that, in particular situations, can overcome and express their virulence factors: to better understand the mechanisms of these pathologies it's necessary to know the complex interactions between all the bacterial species inside the biofilm and host tissues and responses. The present paper is a review of the most significant studies on the biofilm development modalities, their correlations with either health or illness of the oral cavity, the bacterial co-aggregation strategies and the biofilm response to antimicrobial agents.     

Involvement of antigen I/II surface proteins in Streptococcus mutans and Streptococcus intermedius biofilm formation

BACKGROUND/AIM: Dental diseases are caused by microorganisms organized in biofilms. Streptococcus mutans and Streptococcus intermedius are commensals of the human oral cavity. S. mutans is associated with caries, whereas S. intermedius is associated with purulent infections. Oral streptococci including S. mutants and S. intermedius express a family of surface proteins termed antigen I/II (Ag I/II). Ag I/II is implicated in adhesion; however, its role in biofilm formation has not yet been investigated. METHODS: By using isogenic Ag I/II-deficient mutants of S. mutans and S. intermedius we studied the influence of Ag I/II on in vitro biofilm formation. Biofilm was quantified in polystyrene microtiter plates and visualized by scanning electron microscopy. Ag I/II expression in planktonic and biofilm cells, as well as in the presence or absence of saliva was investigated by immunoblotting. RESULTS: In the presence of saliva, the Ag I/II-deficient mutants formed 65% less biofilm than the wild-types. In the absence of saliva, no difference was observed in S. mutans, whereas the S. intermedius Ag I/II mutant formed 41% less biofilm. Ag I/II expression was reduced in the presence of saliva. No differences in expression were observed between biofilm and planktonic cells. CONCLUSION: The results indicated that Ag I/II may be important during biofilm formation particularly in the presence of saliva. These findings may provide useful information regarding the importance of Ag I/II in biofilm formation and in the search of new strategies to control biofilm-mediated infections.     

Biofilm–substrate interaction: from initial adhesion to complex interactions and biofilm maturity

The bacteria‐related diseases of dental caries, pulp and periapical infections, and diseases of the periodontium are biofilm diseases. Dental plaque exhibits the general properties of biofilms and an understanding of biofilm development in health and disease is crucial to the understanding of dental disease, and will unlock effective targeted treatment strategies. Biofilm development requires complex interactions between microorganisms, and with the host. Initially planktonic cells in the aqueous environment of the oral cavity attach to host surfaces, first by physical forces though ultimately by specific adhesive reactions between host and bacteria molecules. Initial bacterial colonizers alter the immediate environment and offer additional binding sites to other bacteria that cannot react directly with the host surface. These co‐aggregation reactions allow various bacterial species to join the evolving community and participate in its development. Development of the microbial community is also dependent on the nutritional source. Early colonizing bacteria are adept at utilizing the immediate nutritional source at the host site, primarily carbohydrates. With the accumulation of bacteria, nutritional demands become more complex and proteins, amino acids, glycoproteins, and vitamins must be supplied from either the host tissues or other bacteria. The biofilm community must co‐operate to effectively achieve metabolism of these complex molecules and perform other functions, while other interbacterial inhibitory reactions such as bacteriocin production or quorum sensing occur in the biofilm, influencing the development of the bacterial community. As such, oral bacteria do not exist independently but function as a co‐ordinated, spatially organized, and metabolically integrated microbial community.     

In situ biofilm formation by multi-species oral bacteria under flowing and anaerobic conditions

An understanding of biofilm behavior of periodontopathic bacteria is key to the development of effective oral therapies. We hypothesized that interspecies bacterial aggregates play an important role in anaerobic biofilm establishment and proliferation, and contribute to the survivability of the biofilm against therapeutic agents. The system developed in this study assessed a multi-species (Streptococcus gordonii, Actinobacillus actinomycetemcomitans, and Fusobacterium nucleatum) biofilm formation under anaerobic and flowing conditions with the use of an in situ image analysis system. The biofilm was comprised of a base film of non-aggregated cells and complex interspecies aggregates that formed in the planktonic phase which rapidly colonized the surface, reaching 58 +/- 9% and 65 +/- 11.8% coverage by 5 and 24 hrs, respectively. Upon SDS (0.1%) treatment of a 24-hour biofilm, substantial detachment (55 +/- 14%, P < 0.05) of the aggregates was observed, while the base film bacteria remained attached but non-viable. Rapid re-establishment of the biofilm occurred via attachment of viable planktonic aggregates.     

口腔致病菌在生物膜状态和浮游态中的特性比较

在人类口腔中存在着种类繁多的天然菌群,这些细菌以牙菌斑生物膜的形式生长.菌斑生物膜作为人类龋病和牙周病的主要致病因素,有诸多代谢特点和生理现象明显不同于浮游态的细菌.下面就数种主要的口腔致病菌在生物膜状态和浮游态下的特性,如对抗菌剂的敏感性、基因表达和信号传导、耐酸性等方面的研究进展作一综述.     

口腔细菌生物膜对抗菌剂的敏感性

许多研究证实生物膜中的细菌对抗菌剂的敏感性比其处于浮游状态时要低得多 ,而口腔细菌却常以生物膜方式致病 ,对许多抗菌剂具有很强的抵抗力 ,这就造成实验室的药敏结果用于临床效果不佳。因此详细了解处于生物膜状态的口腔细菌对抗菌剂的敏感性 ,对于临床上治疗和预防许多口腔疾病具有重要意义     

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。     

Application of the Zürich biofilm model to problems of cariology

The term biofilm is increasingly replacing 'plaque' in the literature, but concepts and existing paradigms are changing much more slowly. There is little doubt that biofilm research will lead to more realistic perception and interpretation of the physiology and pathogenicity of microorganisms colonizing plaques in the oral cavity. There is clear evidence that the genotypic and phenotypic expression profiles of biofilm and planktonic bacteria are different. Several techniques are available today to study multispecies biofilms of oral bacteria, each having its particular advantages and weaknesses. We describe a biofilm model developed in Zürich and demonstrate a number of applications with direct or indirect impact on prophylactic dentistry: spatial arrangement and associative behavior of various species in biofilms; multiplex fluorescent in situ hybridization analysis of oral bacteria in biofilms; use of the biofilm model to predict in vivo efficacy of antimicrobials reliably; mass transport in biofilms; de- and remineralization of enamel exposed to biofilms in vitro. The potential of biofilm experimentation in oral biology has certainly not yet been fully exploited and dozens of possible interesting applications could be investigated. The overall physiological parameters of multispecies biofilms can be measured quite accurately, but it is still impossible to assess in toto the multitude of interactions taking place in such complex systems. What can and should be done is to test hypotheses stemming from experiments with planktonic cells in monospecies cultures. In particular, it will be interesting to investigate the relevance to biofilm composition and metabolism of specific gene products by using appropriate bacterial mutants.