The effect of sodium hypochlorite on Enterococcus faecalis when grown on dentine as a single‐ and multi‐species biofilm

Enterococcus faecalis is often involved in the aetiology of apical periodontitis after endodontic treatment. This project aimed to establish, on dentine in vitro, a multi‐species biofilm containing E. faecalis, and to determine if the organism had an increased resistance to sodium hypochlorite compared with an axenic biofilm. Biofilms were established on dentine discs in flow cells with either E. faecalis alone (axenic) or together with Fusobacterium nucleatum and Streptococcus sanguinis. Following treatment with either 0.9% sodium hypochlorite or saline, the viability of E. faecalis was determined by serial plating and qualitative analysis was performed by scanning electron microscopy and confocal laser scanning microscopy. Viable counts indicated that 0.9% NaOCl is highly effective against E. faecalis grown alone and as part of a multi‐species biofilm (P = 0.0005 and P = 0.001, respectively). No significant difference in its survival in the two biofilm types was found (P = 0.8276).     

再感染根管内粪肠球菌生物膜的研究进展

粪肠球菌是顽固性和继发性根管感染中最易分离到的细菌,其主要致病机制之一是形成生物膜.笔者下面就再感染根管内粪肠球菌的分离与鉴定、影响粪肠球菌生物膜形成的相关因素等作一综述.     

再治疗根管粪肠球菌生物膜形成与临床表现相关性分析

目的检测粪肠球菌形成生物膜的能力,探讨其生物膜形成能力与临床表现之间的关系。方法采用96孔板法形成生物膜,结合结晶紫染色,检测临床样本中分离的53株粪肠球菌形成生物膜的能力,分析其生物膜形成能力与患牙临床表现之间的关系。结果53株粪肠球菌中,40株（75.47%）具有生物膜形成能力;在患牙的多种临床表现中,瘘道与再治疗根管粪肠球菌生物膜形成具有相关性,结果具有统计学意义（P＜0.05）。结论再治疗根管中,无瘘道的患牙分离出来的粪肠球菌生物膜形成能力强于有瘘道的患牙,临床治疗中应予以注意。     

Antibacterial efficacy of casein-derived peptides against Enterococcus faecalis

Background : The aim of this study was to test a casein peptide in its glycosylated form (kappa‐casein glycopeptide, KCGP) and its non‐glycosylated form (kappa‐casein peptide, KCP) for antibacterial efficacy against Enterococcus faecalis in planktonic and biofilm cultures. Methods : E. faecalis strain JKD 15036 was exposed to different concentrations of KCGP and KCP in a 96‐well culture plate. The effect of the peptides on the growth of E. faecalis in planktonic culture was monitored by measuring optical density over 7 hours. Biofilm formation was measured after 24 hours using a crystal violet assay. All experiments were performed in triplicate. Results : KCGP and KCP inhibited growth of E. faecalis in planktonic culture with no significant difference in activity between the peptides. KCGP at 0.16% w/v was significantly better at inhibiting E. faecalis biofilm formation than KCP at the same concentration and significantly better than NaOCl at 1.0% w/v. Conclusions : KCGP effectively inhibited E. faecalis biofilm formation and may have potential to augment the efficacy of traditional antiseptic agents.     

根管治疗后疾病与粪肠球菌

根管治疗后疾病中最常发现的细菌是粪肠球菌,有效清除粪肠球菌与提高根管治疗治疗术成功率存在着联系。本文就这方面的研究现状进行综述。     

粪肠球菌体外根尖生物膜模型的建立及形态学研究

目的 通过体外实验建立根尖生物膜模型,观察粪肠球菌根尖生物膜模型的形态及结构。方法 选取人新鲜拔除的单根离体牙24颗,随机分为8组,每组3颗,浸泡于粪肠球菌 ATCC 29212菌悬液中,分别于1、2、7d建立根尖生物膜模型。使用扫描电子显微镜（ SEM）观察生物膜形成过程;使用碘化丙啶（PI）和刀豆球蛋白 A异硫氰酸荧光素（ConA-FITC）对生物膜细菌及细胞外基质进行双染色,通过激光共聚焦扫描电子显微镜（CLSM）观察其形态和结构;计算生物膜覆盖率。结果 随时间的增加,根尖样本表面细菌覆盖面积增加,7d组与1、2d组间的差异存在统计学意义（P<0.05）, 1d与2d组间的差异无统计学意义（P>0.05）。 7d组形成生物膜结构,其样本表面的覆盖率为 17.23%±1.52%,样本表面有大量细菌附着,细菌被细胞外基质包绕,并呈群落分布。生物膜中的细菌被 PI染成红色,细胞外基质被 ConA-FITC染成绿色,可见多层次的空间结构以及亲水性通道。结论 粪肠球菌根尖生物膜于培养7d时形成完整的生物膜结构,由细菌群落及其周围大量的不定型基质组成。     

根管冲洗液对粪肠球菌作用的研究进展

粪肠球菌是一种最常见的导致根管治疗失败的细菌,如何控制根管内的粪肠球菌是研究的热点。根管冲洗剂是杀灭和抑制粪肠球菌的有效方法之一,本文就根管内粪肠球菌的感染特点、常用根管冲洗液以及冲洗剂联合使用对其的作用等方面作一综述。     

激光扫描共聚焦显微镜观察碱性环境对粪肠球菌生物膜的影响

目的:比较不同碱性条件对生物膜状态粪肠球菌的影响。方法:制备粪肠球菌生物膜,分别用pH值为7、9和11的TSB培养液作用2 h后,用激光扫描共聚焦显微镜观察粪肠球菌生物膜的变化。结果:pH值由7升到9时,生物膜内、中、外各层活菌比例虽有所减少,但差异无统计学意义(P>0.05);当pH值11时,各层活菌比例虽然均较pH值为7和9时明显减少(P<0.05),但仍有大量活菌存在。结论:粪肠球菌对碱性环境具有强的耐受性,pH值为7～9时,对生物膜状态粪肠球菌无明显影响。     

饥饿状态的粪肠球菌的研究进展

作为顽固性或继发性根管内感染的主要致病菌,粪肠球菌可以饥饿状态在恶劣的环境中长期生存。在饥饿状态下,粪肠球菌可保持较低的代谢水平并形成生物膜,从而提高其对外界刺激的耐受水平。本文就饥饿状态与活的不可培养状态,饥饿状态下的粪肠球菌的生长状况,饥饿状态下的粪肠球菌的生物膜形成能力,饥饿状态下的粪肠球菌对外界刺激的耐受水平等研究进展作一综述。     

Residual and antimicrobial activity of final irrigation protocols on Enterococcus faecalis biofilm in dentin

Introduction

The use of root canal irrigating solutions exerting antimicrobial activity and prolonged residual activity is desirable in order to control dentin infection and delay reinfection of the root canal. The aim of this study was to evaluate the residual antimicrobial activity and the capacity to eradicate Enterococcus faecalis biofilm of different irrigating solutions, alone and in combination, in a dentin-volumetric test.

Methods

Solutions of 2.5% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), 0.2% cetrimide (CTR), 17% ethylendiaminetetraacetic (EDTA), 7% maleic acid (MA), and regimens of 2.5% NaOCl followed by 17% EDTA or 7% MA and 0.2% CTR or 2% CHX were used to determine their residual activity by exposing treated dentin blocks to E. faecalis for 24 hours. Antimicrobial activity was assayed on 3-week biofilm formed on dentin blocks. Results of residual activity and antimicrobial activity were respectively expressed as the inhibition percentage of biofilm formation and the kill percentage of biofilm.

Results

A 2% CHX and 0.2% CTR solution showed 100% biofilm inhibition; 2.5% NaOCl showed the lowest residual activity (18.10%). The kill percentage of 2.5% NaOCl and 0.2% CTR was 100% followed by 7% MA and 2% CHX, whereas 17% EDTA was the least effective (44%). Solutions of 7% MA or 17% EDTA followed by 0.2% CTR or 2% CHX showed 100% residual and antimicrobial activity.

Conclusions

A 0.2% CTR solution alone and the combinations in which 2% CHX or 0.2% CTR was the final irrigating solution achieved the maximum residual and antimicrobial activity.     

不同根管冲洗方式对粪肠球菌生物膜清除效果评价

目的 比较不同根管冲洗方式对粪肠球菌感染根管预备、冲洗的清除效果,评价不同根管冲洗液残余药量的抗菌效果,为临床上选择根管冲洗方法提供参考。方法 将32颗离体牙（前磨牙、单根管）消毒,接种粪肠球菌60 d,随机分为4组（第1组：生理盐水;第2组：生理盐水+超声1 min;第3组：1%NaOCl;第4组：1%NaOCl+超声1 min）,使用ProTaper器械按照冠向下法进行根管预备,并在预备冲洗前及预备至F2进行冲洗后分别取样、计数,进行统计学分析。将预备好的离体牙再次消毒,随机分为2组,分别浸泡生理盐水和1%NaOCl;浸泡30 min后取出,置于接种粪肠球菌标准菌株（ATCC33186）的培养液内,分别在培养2、6、24、48 h时取样、计数。采用SPSS19.0软件包对数据进行统计学分析。结果 4组在预备至F2冲洗结束后,根管中的细菌数量均不同程度降低,其中,使用1% NaOCl结合超声冲洗1 min,几乎可完全去除根管内的细菌。经1% NaOCl浸泡的牙根样本内的细菌,在培养48 h时后总量少于生理盐水。结论 1%NaOCl是有效的根管冲洗液,用于根管化学预备后的残余液体,也可发挥有效的抗菌效果。联合使用超声器械,可以使其抗菌效果最大化。     

Evaluation of the effectiveness of sodium hypochlorite used with three irrigation methods in the elimination of Enterococcus faecalis from the root canal, in vitro

The effectiveness of 4.0% sodium hypochlorite (NaOCl) used with three irrigation methods in the elimination of Enterococcus faecalis from the root canal was tested in vitro . Root canals contaminated with E. faecalis were treated as follows: (i) irrigation with 2 mL of NaOCl solution and agitation with hand files; (ii) irrigation with 2 mL of NaOCl solution and ultrasonic agitation; (iii) irrigation with NaOCl alternated with hydrogen peroxide. Contaminated canals irrigated with sterile saline solution served as the control. Paper points used to sample bacteria from the root canals were transferred to tubes containing 5 mL of brain heart infusion (BHI) broth. Tubes were incubated and the appearance of broth turbidity was indicative of bacteria remaining in the root canal. There were no statistically significant differences between the experimental groups. However, NaOCl applied by the three methods tested, was significantly more effective than the saline solution (control group) in disinfecting the root canal.     

纳米银对多菌种生物膜中粪肠球菌的杀菌作用

目的:研究纳米银对多菌种生物膜中粪肠球菌的杀菌作用.方法:用粪肠球菌、产黑色素普雷沃菌以及具核梭杆菌构建多菌种生物膜85 个.分别用0.1%(12~15 nm、100 nm)纳米银悬浊液以及2%的次氯酸钠溶液处理,然后通过qPCR方法检测样本中粪肠球菌的活菌量和粪肠球菌的细菌总量.配对t检验比较各组细菌样本临界循环数(Ct).结果:各个实验组使用和不使用PMA之间粪肠球菌的细菌计数有着差别(P=0.000);将3 个实验组使用和不使用PMA qPCR检测到的Ct值的差值进行比较:纳米银(12~15 nm)实验组最大,纳米银(100 nm)实验组次之,次氯酸钠实验组最小(P<0.05).结论:纳米银对于多菌种生物膜中的粪肠球菌有着较强的杀菌作用,直径较小的纳米银杀菌作用较强.