超氧化物阴离子自由基与龋病关系的初步研究

超氧化物阴离子自由基（Ｏ２－·）是致龋菌代谢过程中产生的重要的中间产物，关于（Ｏ２－·）与龋病关系的研究，目前主要有两个方面，一是氧代谢对龋病发病的作用，把Ｏ２－·作为致龋菌氧代谢的产物，认为变链球菌代谢过程中产生了Ｏ２－·，而Ｏ２－·通过影响菌斑的...     

蜂胶对不同龋敏感者变形链球菌临床分离株产酸影响的体外实验研究

目的研究蜂胶提取物对不同龋敏感者口腔变形链球菌临床分离株的产酸能力的影响。方法以BHI液体培养基为溶剂，分别配制pH=7．0的5g／L和1．25g／L水溶性蜂胶溶液，1．5625g／L醇溶性蜂胶溶液，并以空白液体培养基作为对照，加入高龋组，无龋组，国际标准株变形链球菌，厌氧培养48h后离心，用精密酸度仪测定上清的pH值，计算出△pH，并进行比较。结果高龋组和国际标准株产酸能力明显高于无龋组；醇溶性蜂胶溶液和水溶性蜂胶溶液皆可使变链菌产酸能力降低。蜂胶各组与对照组相比差异均有统计学意义（P〈0．05）。醇溶性蜂胶溶液和5g／L水溶性蜂胶溶液降低产酸能力的作用比较差异无统计学意义（P〉0．05），但是均明显高于1．25g／L水溶性蜂胶溶液；蜂胶对高龋组和无龋组细菌的影响没有显著性差异。结论蜂胶提取物影响变形链球菌的代谢，使变形链球菌产酸能力降低。     

细菌外排泵抑制剂对光动力疗法杀灭牙菌斑生物膜内主要致龋菌作用的影响

目的:探讨细菌外排泵抑制剂(microbial efflux pump Inhibitor,EPI)——维拉帕米对以血卟啉单甲醚(hematoporphyrin monomethylether,HMME)为光敏剂的光动力疗法(photo-dynamic therapy,PDT)杀灭牙菌斑生物膜内主要致龋菌的影响。方法:以变形链球菌、血链球菌、嗜酸性乳杆菌和粘性放线菌为实验菌株,建立牙菌斑生物膜模型。以维拉帕米     

细菌外排泵抑制剂对光动力疗法抑制牙菌斑生物膜内主要致龋菌作用的影响

目的探讨细菌外排泵抑制剂(microbial efflux pump Inhibitor,EPI)——维拉帕米对以血卟啉单甲醚(hematoporphyrin monom-ethylether,HMME)为光敏剂的光动力疗法(photodynamic therapy,PDT)抵抗牙菌斑生物膜内主要致龋菌作用的影响。方法以变形链球菌、血链球菌、嗜酸性乳杆菌和粘性放线菌为实验菌株,建立牙菌斑生物膜模型。以维拉帕米作为细菌外排泵抑制剂,根据在PDT过程中加入维拉帕米和光敏剂的先后顺序,实验分为5组:A组:同时加入光敏剂和维拉帕米PDT处理组,B组:先加入维拉帕米后加入光敏剂PDT处理组,C组:先加入光敏剂后加入维拉帕米PDT处理组,D组:单纯PDT处理组,E组:生理盐水处理组。激光照射后平板菌落计数观察PDT作用后牙菌斑内致龋菌的活力。结果与生理盐水处理组相比,单纯PDT处理组牙菌斑内致龋菌存活的数量(CFU/mL)明显减少(P<0.05),其抑菌率高达95.26%,与单纯PDT处理组相比,加入维拉帕米的PDT处理组内牙菌斑内致龋菌存活数量有上升趋势。其中先加入维拉帕米后加入光敏剂PDT处理组牙菌斑内致龋菌存活数量显著性上升(P<0.05),抑菌率仅为80.92%。结论 HMME-PDT可以通过有效抑制致龋菌的生长而起到防龋的作用。细菌外排泵抑制剂对HMME-PDT抑制牙菌斑生物膜内主要致龋菌有抑制作用。     

苯扎溴铵对ICU内泛耐药鲍曼不动杆菌杀灭效果的研究

目的研究苯扎溴铵对ICU内分离的泛耐药鲍曼不动杆菌(PDR-Ab)的杀菌效果及抗性。方法采用最低抑菌浓度(MIC)、悬液定量杀菌试验,观察苯扎溴铵对ICU内分离的PDR-Ab的杀菌效果,并与大肠埃希菌标准菌株进行对比;采用PCR法检测PDR-Ab中qacE△1-sulI的携带情况。结果苯扎溴铵对65株PDR-Ab的MIC值是9~36 mg/L,大部分高于标准菌株;500 mg/L苯扎溴铵作用5 min以上对PDR-Ab的杀灭对数值>5.00;65株PDR-Ab中51株携带qacE△1-sulI基因,检出率78.46%。结论 ICU内PDR-Ab携带qacE△1-sulI基因携带率高,提示ICU内的PDR-Ab对苯扎溴铵存在抗性。     

产ESBLs宋内志贺菌耐药基因分布研究

目的探讨产ESBLs宋内志贺菌的耐药机制,为腹泻疾病的临床治疗提供依据。方法收集2004~2007年解放军302医院门诊腹泻患者分离的多重耐药AmpR、SxtR、CtxR的宋内志贺菌43株,用PCR方法扩增耐药基因,并将菌株进行质粒结合试验。结果携带CTX-M基因27株,其中CTX-M1群16株,CTX-M9群11株,占所有阳性分离株的62.79%;携带TEM基因18株,占41.86%;未检出SHV、OXA和PER基因。同时携带CTX和TEM基因占23.26%。携带2类整合子的宋内志贺菌占95.35%（41/43）。质粒结合试验成功率为92.7%。结论北京地区产ESBLs宋内志贺菌以携带CTX-M基因为主,其次为TEM型。流行亚型为CTX-M-15like、CTX-M-14和TEM-1。2类整合子在产ESBLs宋内志贺菌中多见。耐药基因大多通过质粒水平转移的方式进行传播。产CTX-M-27和CTX-M-64的宋内志贺菌在世界和国内分别属首次报告检出。     

亚苄基环戊酮介导的光动力对多重耐药铜绿假单胞菌的体外杀伤效应

目的探讨新型光敏剂亚苄基环戊酮化合物P3介导的光动力对多重耐药铜绿假单胞菌的体外杀伤效应。方法实验对象为铜绿假单胞标准菌(ATCC27853)1株和临床多重耐药菌(PA1、PA2、PA3)3株。(1)检测实验菌株与光敏剂P3的结合特性:以荧光光谱检测法检测孵育时间和孵育浓度对实验菌株与光敏剂P3结合的影响,先将4株铜绿假单胞菌与10μM光敏剂分别孵育不同时间(5、15、30、60、120和150 min),根据前期的检测结果再选择不同浓度(2. 5、5、10、25和50μM)的光敏剂P3孵育30 min。(2)观察光敏剂P3介导的PDT对铜绿假单胞菌的体外光动力抗菌效应,即PDT组(B组),按照不同浓度的光敏剂P3分为4组分别为2. 5μM(B1组)、5μM(B2组)、10μM(B3组)和25μM(B4组),药物与4种菌株的孵育时间30 min后,进行PDT处理,激光波长532 nm,功率密度40 mW/cm2,照射时间600 s,同时设立3个对照组(A组):空白对照组(A1组)、单纯照光组(A2组)和单纯光敏剂组(A3组),用稀释平板法培养24 h进行菌落计数。结果孵育时间5～30 min时,四株铜绿假单胞菌与光敏剂P3的结合量随孵育时间延长而逐渐增加;30 min后趋于饱和。浓度梯度实验结果显示,四株铜绿假单胞菌与光敏剂P3的结合量呈孵育浓度剂量依赖性增加。在相同孵育浓度和相同孵育时间条件下,四株铜绿假单胞菌与光敏剂P3的结合量未见显著差异。光敏剂P3对四株铜绿假单胞菌的PDT杀伤作用随着光敏剂P3浓度增高逐渐增强,当光敏剂P3浓度为25μM时,PDT对4株铜绿假单胞菌株均达到有效杀伤,即活性下降均4Log;光敏剂P3对铜绿假单胞标准菌和临床耐药菌的PDT杀伤效应比较,差异无统计学意义(P0. 05);单纯照光和单纯光敏剂对细菌的存活无影响。结论光敏剂P3介导的PDT对铜绿假单胞菌有良好的体外杀伤作用,其作用不受细菌耐药性的影响。     

腹泻病原菌中产超广谱β-内酰胺酶菌株的基因型和同源性分析

目的了解分离的产超广谱β-内酰胺酶(ESBLs)腹泻病原菌的基因流行情况。方法采用TEM型、SHV型和CTX-M型ESBLs编码基因的通用引物对产ESBLs菌株进行扩增,并采用PFGE技术对分离的产ESBLs腹泻病原菌进行了DNA指纹图谱分析。结果在分离的产ESBLs的腹泻病原菌中,CTX-M型是最为常见的ESBLs型别,TEM型次之,SHV型最少,CTX-M亚型中CTX-M-14最多,部分产ESBLs腹泻病原菌同时产生一种以上的β-内酰胺酶,少数菌株的ESBLs基因型不属于上述三种基因型。分离的产ESBLs的大肠杆菌有6种基因型,宋内菌有2种基因型,变形杆菌和克雷伯菌只有1种基因型。结论 ESBLs不仅可以存在于不同种的细菌中,也可以存在同一种细菌的不同基因型中,推测这可能是耐药基因在不同细菌或同一细菌不同基因型中平行转移的结果。     

加替沙星与环丙沙星对社区获得性感染常见致病菌体外抗菌活性比较

目的比较加替沙星与环丙沙星对社区获得性感染常见致病菌的体外抗菌活性。方法采用琼脂稀释法测定药物对172株临床分离菌株的最低抑菌浓度。结果革兰阴性菌中,ESBLs(-)肺炎克雷伯菌、铜绿假单胞菌、肠杆菌属对2种药物的敏感率均在90%以上;大肠埃希菌、ESBLs(+)肺炎克雷伯菌、变形杆菌对2种药物的敏感率相对较低,但也在70%以上;不动杆菌、沙雷菌属的MIC90为1~2μg·ml-1;革兰阳性菌中,葡萄球菌属的敏感率较高,其中对加替沙星的敏感率为96.2%,高于环丙沙星的88.5%。链球菌属对加替沙星与环丙沙星的敏感性差。结论加替沙星与环丙沙星对社区获得性感染常见致病菌有较强的抗药活性。     

耐利福平金黄色葡萄球菌突变株体内选择的临床研究

目的 对耐药突变选择窗（MSW）和金黄色葡萄球菌耐药突变株体内选择的关系进行初步研究。方法 选择前鼻腔携带金黄色葡萄球菌的结核患者为实验组，观察含利福平（RFP）联合化疗方案治疗前及治疗2、4、5周后金黄色葡萄球菌对RFP敏感性的变化，对获得性RFP耐药患者治疗前后分离的菌株进行分子分型。以前鼻腔携带金黄色葡萄球菌的糖尿病患者为对照组。结果 实验组58例患者治疗后有5例前鼻腔携带的金黄色葡萄球菌获得RFP耐药，脉冲场凝胶电泳和蛋白A分子分型结果表明这5例患者携带的菌株不同，但同一患者治疗前后分离的菌株同源。对照组39例患者中无耐药菌株出现。结论 耐利福平的金黄色葡萄球菌突变株的选择性富集是在MSW内完成的。     

Surface-enhanced Raman spectroscopy for the characterization of pellets of biofilm forming bacterial strains of Staphylococcus epidermidis

BackgroundSurface-enhanced Raman spectroscopy (SERS) is an effective tool for identifying biofilm forming bacterial strains. Biofilm forming bacteria are considered a major issue in the health sector because they have strong resistance against antibiotics. Staphylococcus epidermidis is commonly present on intravascular devices and prosthetic joints, catheters and wounds.ObjectivesTo identify and characterize biofilm forming and non-biofilm forming bacterial strains, surface- enhanced Raman spectroscopy with principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) were used.MethodsSurface-enhanced Raman spectroscopy (SERS) with silver nanoparticles were employed for the analysis and characterization of biofilm forming bacterial strains. SERS is used to differentiate between non biofilm forming (five samples), medium biofilm forming (five samples) and strong biofilm forming (five samples) bacterial strains by applying silver nanoparticles (AgNPs) as SERS substrate. Principal component analysis (PCA) and Partial least square discriminant analysis (PLS-DA) were used to discriminate between non, medium and strong biofilm ability of bacterial strains.ResultsPrincipal component analysis (PCA) and Partial least square discriminant analysis (PLS-DA) have been used to identify the biochemical differences in the form of SERS features which can be used to differentiate between biofilm forming and non-biofilm forming bacterial strains. PLS-DA provides successful differentiation and classification of these different strains with 94.5% specificity, 96% sensitivity and 89% area under the curve (AUC).ConclusionsSurface-enhanced Raman spectroscopy can be utilized to differentiate between non, medium and strong biofilm forming bacterial strains.     

临床分离鲍曼不动杆菌生物被膜形成能力研究

目的 研究鲍曼不动杆菌(AB)临床分离菌株生物被膜形成能力,为医院感染AB生物被膜检测平台的建立奠定基础,为AB医院感染的预防和控制提供依据.方法 采用半定量结晶紫染色法,检测临床标本分离的AB生物被膜形成能力.结果 (1)100株AB中,81株具有生物被膜形成能力,其中形成能力弱阳性14株(17.28％),阳性21株(25.93％),强阳性46株(56.79％);另19株生物被膜形成检测试验阴性.(2)不同标本来源的AB均具有生物被膜形成能力.(3)AB生物被膜形成能力与体外抗菌药物耐药性呈负相关.结论 AB生物被膜形成能力较强.半定量结晶紫染色法简便易操作,无需特殊设备,可以作为监测医院感染AB生物被膜形成能力的常规方法.     

Antibacterial photodynamic therapy for dental caries: evaluation of the photosensitizers used and light source properties

Photodynamic therapy studies have shown promising results for inactivation of microorganisms related to dental caries. A large number of studies have used a variety of protocols, but few studies have analyzed photosensitizers and light source properties to obtain the best PDT dose response for dental caries. This study aims to discuss the photosensitizers and light source properties employed in PDT studies of dental caries. Three questions were formulated to discuss these aspects. The first involves the photosensitizer properties and their performance against Gram positive and Gram negative bacteria. The second discusses the use of light sources in accordance with the dye maximum absorbance to obtain optimal results. The third looks at the relevance of photosensitizer concentration, the possible formation of self-aggregates, and light source effectiveness. This review demonstrated that some groups of photosensitizers may be more effective against either Gram positive or negative bacteria, that the light source must be appropriate for dye maximum absorbance, and that some photosensitizers may have their absorbance modified with their concentration. For the best results of PDT against the main cariogenic bacteria (Streptococcus mutans), a variety of aspects should be taken into account, and among the analyzed photosensitizer, erythrosin seems to be the most appropriate since it acts against this Gram positive bacteria, has a hydrophilic tendency and even at low concentrations may have photodynamic effects. Considering erythrosin, the most appropriate light source should have a maximum emission intensity at a wavelength close to 530 nm, which may be achieved with low cost LEDs.     

Effects of photodynamic therapy on Streptococcus mutans and enamel remineralization of multifunctional TiO2-HAP composite nanomaterials

BackgroundAs photosensitizer and photocatalyst, titanium dioxide (TiO₂) can produce a photodynamic reaction for antibacterial treatment. This study aims to explore a Titanium dioxide/nano-hydroxyapatite (TiO₂-HAP) composite combined with the dental curing lamp (385–515 nm) in clinical which could inhibit the dental plaque biofilm formed by Streptococcus mutans (S. mutans) and promote the enamel surface remineralization simultaneously.MethodsX-ray Diffraction (XRD) and high resolution transmission electron microscope (HRTEM) were used to detect the characterization of TiO₂-HAP composite nanomaterials. Photodynamic properties of TiO₂-HAP were detected by Diffuse reflectance spectrum (DRS) and fluorescence spectroscopy. Bacterial growth was measured by reading the absorbance of bacterial cultures and confocal microscope was used to observe the biofilm removal ability of nanomaterials. The ability of TiO₂-HAP to promote enamel remineralization was measured by Scanning electron microscope (SEM).ResultsThe OD 600 of S. mutans was 0.76 in the control group and 0.13 in group of TiO₂-HAP with exposure to light-emitting diode (LED) (150 mW/cm²) for 5 min, suggesting its sustained antibacterial potency and inhibition of the metabolic activity of dental plaque microcosm biofilm. Also, the release of calcium and phosphorus ions in TiO₂-HAP can promote enamel mineralization simultaneously. After 15 days of remineralization, the Ca/P ratio of demineralized enamel surface increased from 1.28 to 1.67, which was similar to that of normal enamel.ConclusionsThe TiO₂-HAP exhibit a promising anti-bacterial activity and remineralization capacity which can prevent the occurrence of caries to the greatest extent and promote the biomimetic mineralization of dental tissues.     

The Impact of Photosensitizer Selection on Bactericidal Efficacy Of PDT against Cariogenic Biofilms: A Systematic Review and Meta-Analysis

BackgroundThere are investigations on multiple photosensitizers for modulation of caries-related biofilms using PDT. However, much controversy remains about recommended parameters mostly on the selection of an efficient photosensitizer.ObjectiveThe study performed a systematic review to identify the answer to the following question: What photosensitizers present high bactericidal efficacy against cariogenic biofilms?MethodsSystematic review with meta-analyses were carried out for English language articles from October to December 2019 (PRISMA standards) using MEDLINE, Scopus, Biomed Central, EMBASE, LILACS, and Web of Science. Information on study design, biofilm model, photosensitizer, light source, energy delivery, the incubation time for photosensitizer, and bacterial reduction outcomes were recorded. We performed two meta-analyses to compare bacterial reduction, data was expressed by (1) base 10 Logarithm values and (2) Log reductionResultsAfter the eligibility criteria were applied (PEDro scale), the selected studies showed that toluidine Blue Ortho (TBO) and methylene blue (MBO) (5-min incubation time and 5-min irradiation) demonstrated better bacterial reduction outcomes. For the data expressed by Log TBO, MBO, curcumin, and Photogem® presented a significant bacterial decrease in comparison to the control (p = 0.042). For the data represented by Log reduction, the bacterial reduction toward S.mutans was not significant for any photosensitizer (p = 0.679).ConclusionThe lack of methodological standardization among the studies still hinders the establishment of photosensitizer and bactericidal efficiency. TBO, MBO, curcumin, and photogem generate greater PDT-based bacterial reduction on caries-related bacteria.. Further clinical studies are necessary in order to obtain conclusive results.     

牙放射性损伤的临床研究

目的　分析牙放射性损伤的各种因素及防治方法。方法　放疗后病人 10 0例 ,其中牙照射组 6 0例 ,牙未照射组 4 0例。自身对照组 15例。治疗方法均为常规分割照射。结果　两组分别在 2 0个月内龋齿发病率为 6 0 %、15 % ,P <0 0 1。自身对照组 15例患侧发病率明显高于健侧。 6例患者牙的吸收剂量为 70Gy者发病率为 10 0 %。结论　作者认为放射性牙损伤 :(1)与吸收剂量、放射部位有密切关系。 (2 )牙齿内活跃的造釉细胞、造牙本质细胞对射线敏感。 (3)唾液腺的破坏造成唾液素下降pH值下降 ,链球菌大量繁殖。防治方法 :用防龋涂料 ,牙罩 ,计划性保护唾液腺 ,调整时间剂量因子 ,选择适形放疗技术 ,保护牙髓细胞的增殖能力 ,抗炎 ,改善微循环 ,增强全身抵抗力 ,是防龋齿的关键。     

Antimicrobial photodynamic therapy as an adjunct for treatment of deep carious lesions—A systematic review

For deep carious lesions, a more conservative treatment modality (“selective caries removal”) has been proposed, where only the heavily contaminated dentine is removed. In this regard, effective adjuncts for cavity disinfection such as the antimicrobial photodynamic therapy (aPDT) can be valuable clinically prior to definitive restoration. Therefore, the aim of this study was to systematically assess clinical studies on the effectiveness of aPDT as a supplementary tool in the treatment of deep caries lesions. Searches were performed in four databases (PubMed, EMBASE, ISI Web of Science, ClinicalTrials.gov) from 1st January, 2011 until 21st June, 2016 for search terms relevant to the observed parameters, pathological condition, intervention and anatomic entity. The pooled information was evaluated according to PRISMA guidelines. At first, 1651 articles were recovered, of which 1249 full-text articles were evaluated, 270 articles thereof were reviewed for eligibility and finally 6 articles met all inclusion criteria. The aPDT protocols involved Methylene Blue, Toluidine Blue and aluminium-chloride-phthalocyanine as photosensitizers and diode lasers, light-emitting diodes and halogen light-sources. The data from five reports, utilizing both culture-dependent and −independent methods, disclosed significant reduction of cariogenic bacterial load after mechanical caries removal with adjunct aPDT. As these studies exhibit some methodological limitations, e.g. lack of positive controls, this systematic review can support the application of aPDT to a limited extent only in terms of reducing the microbial load in deep carious lesions before restorative treatment.     

Effect of methylene blue-induced photodynamic therapy on a Streptococcus mutans biofilm model

BackgroundSeveral studies have reported the use of antimicrobial photodynamic therapy (aPDT) to control biofilm but its efficacy depends on several factors, such as biofilm model used. This study aims to examine whether exposure to diode laser combined with methylene blue affects the bacterial viability and polysaccharide content in a Streptococcus mutans cariogenic biofilm model, which simulated ‘feast-famine’ episodes of exposure to sucrose that occur in the oral cavity.Materials and methodsS. mutans biofilms were formed on acrylic resin discs and exposed to a 10% sucrose solution for 1 min, eight times/day. After growing for 48 h, the biofilms were submitted to the following treatments, twice daily (n = 4): (i) 0.9% NaCl (NaCl) as the negative control; (ii) 0.12% chlorhexidine digluconate (CHX) as the positive antibacterial control; (iii) diode laser combined with methylene blue, using an energy density of 320 J/cm² (aPDT). After 120 h of growth, the biofilm formed on each disc was collected to determine the viable bacterial counts and concentration of insoluble exopolysaccharides (IEPS) and intracellular polysaccharides (IPS).ResultsBacterial counts in the biofilms formed differed among the treatments. Compared with NaCl, aPDT significantly destabilized biofilm (p < 0.0001). aPDT and CHX equally lowered the concentration of IEPS and IPS in biofilms.ConclusionUnder the experimental conditions assessed, our findings indicate that a twice-daily treatment with diode laser combined with methylene blue effectively decreased bacterial viability and the intra- and extracellular polysaccharide concentration in biofilms of S. mutans, a cariogenic bacterium.     

伢典化学机械去腐法在儿童龋病治疗中应用

目的:评价伢典化学机械去腐法在儿童龋病治疗中的应用效果。方法:40名儿童龋病患者被随机分为两组:伢典化学机械去腐(实验组)20例,患牙20颗;传统磨牙去腐(对照组)20例,患牙22颗,对比两组患儿的感受和治疗效果。结果:伢典组的治疗较传统方法更易为患儿所接受,两者在乐于接受程度上有显著差别,而在治疗效果上无显著差别。结论:伢典化学机械去腐法在儿童龋病治疗中有效且易于被接受。