银杏酸C17:1衍生物增效达托霉素抗粪肠球菌的发现与机制的初步研究

目的 发现有抗菌活性或是增效活性的银杏酸C17:1衍生物。方法 以银杏酸C17:1为底物，利用一些基团取代苯环上的羧基从而获得银杏酸C17:1衍生物，棋盘法设计试验，测定银杏酸C17:1及其衍生物联合抗生素的增效作用，通过测定Zeta电位、ROS、NPN吸收来探究增效机制。结果 银杏酸C17:1衍生物Ⅱ与达托霉素联合抗粪肠球菌的部分抑菌浓度指数(FICIs)为0.125~0.25，具有明显的协同效应，不仅能产生较高的活性氧，而且能在一定程度改变细胞膜的通透性。结论 银杏酸衍生物Ⅱ对达托霉素体外抗耐药株具有较好的增效作用，可能和ROS的激增以及膜通透性的改变有关。     

枯草杆菌二联活菌肠溶胶囊防治经肝动脉化疗栓塞术后不良反应及并发症的效果评价

目的探讨枯草杆菌二联活菌肠溶胶囊对经肝动脉化疗栓塞术(TACE)术后不良反应及并发症的防治作用。方法选取2012年1月-2013年12月大连大学附属中山医院收治的择期进行TACE的肝细胞癌患者239例,随机分为试验组(n=111)与对照组(n=128)。其中试验组于术前3 d给予口服枯草杆菌二联活菌肠溶胶囊,对照组服用外形相同的安慰剂,比较2组TACE术后不良反应、并发症发生率及血氨水平。计量资料组间比较采用独立样本t检验,计数资料组间比较采用χ2检验。结果试验组患者发热、腹胀、便秘等不良反应发生率显著低于对照组,差异均有统计学意义(t值分别为2.728、2.561、2.026,P值均0.05);试验组患者肝脓肿、肠梗阻、自发性腹膜炎、肝性脑病等术后并发症的发生率亦显著低于对照组,差异均有统计学意义(t值分别为1.969、2.312、2.987、2.826,P值均0.05);经治疗后,与对照组相比,试验组患者血氨水平较低,差异具有统计学意义(t=1.97,P0.05)。结论枯草杆菌二联活菌肠溶胶囊作为新型活菌制剂,能够降低TACE术后患者腹部不适及血氨水平,并能够减少肝脓肿等严重并发症的发生,但相关机制尚需进一步研究。     

2014-2017年某医院152例尿路感染肠球菌耐药性监测分析

目的:了解2014年1月-2017年1月某医院尿液标本分离肠球菌的临床特点及耐药情况,为肠球菌经验治疗提供参考依据。方法:回顾性分析2014年1月-2017年1月分离自尿液标本肠球菌,VITEK2-compact微生物鉴定系统对细菌进行鉴定,纸片扩散法联合MIC法行抗生素敏感试验,WHONET 5.6和SPSS 20软件进行统计分析。结果:(1)2014年1月-2017年1月尿液标本共检出病原菌908株,主要是大肠埃希菌,其中屎肠球菌84株,粪肠球菌68株,是位于第2位和第3位的病原菌。(2)屎肠球菌对于氨苄西林、高水平庆大霉素、环丙沙星、左氧氟沙星、呋喃妥因的耐药率分别89.6%,63.2%,91.5%,85.7%,69.4%、明显高于粪肠球菌的24.2%(2=65.001,P=0.000)、40.4%(2=8.246,P=0.004)、56.6%(2=26.129,P=0.000)、51.2%(2=21.144,P=0.000)、12.2%(2=50.193,P=0.000);粪肠球菌对于氯霉素的耐药率为33.3%,显著高于屎肠球菌2.6%(2=27.035,P=0.000)。二者对于喹诺酮类抗生素都有较高的耐药率(51.2%)。(3)检出一株对万古霉素耐药的屎肠球菌,耐药率为1.2%(1/84);未检出对万古霉素耐药的粪肠球菌;未发现对利奈唑胺、替加环素耐药的肠球菌。(4)屎肠球菌多重耐药现象严重。结论:尿液标本屎肠球菌与粪肠球菌对抗菌药物耐药性差异大,屎肠球菌多重耐药现象形势严峻,已发现耐万古霉素的屎肠球菌,必须严密监控,尽早诊治,切断传播链。     

Bioactive composition and antibacterial activity of three herbal extracts (lemongrass,sage, and guava leaf) against oral bacteria: An in vitro study

ObjectiveThe objective of this study was to estimate the antibacterial activity of three different herbal extracts against oral bacteria and their bioactive composition.MethodsUsing the disk diffusion technique, the antibacterial activities of three different extracts (lemongrass, sage, and guava leaf) were evaluated against oral bacteria (Streptococcus mutans, Staphylococcus aureus, and Enterococcus faecalis). Additionally, the bioactive components of the herbal extracts were assessed by employing the gas chromatography-mass spectrometry technique.ResultsThe sage, lemongrass, and guava leaf extracts suppressed the proliferation of all three tested bacterial strains at different rates. The phytochemical analysis revealed that sage extract possessed the highest content of antioxidants, phenols, and flavonoid compounds. The gas chromatography-mass spectrometry analysis of the tested plants revealed the presence of vital bioactive compounds.ConclusionsLemongrass, sage, and guava leaf extracts have potent antibacterial activities, are rich in bioactive compounds, and could be utilized as natural remedies for the prevention of oral diseases.     

Enterococcus faecalis--a mechanism for its role in endodontic failure

AIM: The aim of this study was to identify a possible mechanism that would explain how E. faecalis could survive and grow within dentinal tubules and reinfect an obturated root canal. METHODOLOGY: Cells of Streptococcus gordonii DL1, Streptococcus mutans NG8, or E. faecalis JH2-2 were grown in brain heart infusion broth containing various amounts of human serum for 56 days. The ability of the three species to invade dentine and bind to immobilized type I collagen in the presence of human serum was assessed by dentine invasion and microtitre well experiments. RESULTS: All three species remained viable over the period of the experiment when grown in human serum. Cells of all three bacteria were able to invade dentine and bind to immobilized collagen. Both of these properties were inhibited by the presence of collagen in the cell solution. Human serum inhibited dentine invasion and collagen adhesion by S. gordonii DL1 and S. mutans NG8, whilst dentine invasion by E. faecalis JH2-2 was reduced in the presence of serum, but not inhibited, and binding to collagen was enhanced. CONCLUSIONS: It is postulated that a virulence factor of E. faecalis in failed endodontically treated teeth may be related to the ability of E. faecalis cells to maintain the capability to invade dentinal tubules and adhere to collagen in the presence of human serum.     

Starvation survival,growth and recovery of Enterococcus faecalis in human serum

The ability of Enterococcus faecalis to survive starvation for long periods in the obturated root canal is likely to be an important factor in the pathogenesis and maintenance of a persistent infection after endodontic treatment. The response of E. faecalis to starvation survival in water and glucose‐, phosphate‐ or amino acid‐limited chemically defined medium was studied, along with the capacity for growth and recovery of starved cells of E. faecalis in pooled human serum. After an initial rapid fall in cell numbers, a small remaining population of E. faecalis was able to survive in water for over 4 months and in nutrient‐limited media for extended periods. A high cell density at the onset of starvation was critical for the ability of E. faecalis to endure prolonged nutrient limitation. Upon starvation, a static population of starved cells developed and were apparently in a minimal metabolic state, since blocking cell wall synthesis with penicillin G or inhibiting DNA synthesis with norfloxacin during starvation resulted in limited change in the rate of loss of viable cells. In 50% serum, E. faecalis grew, then stabilized at a relatively constant population of 10⁶ colony‐forming units/ml for 4 months, irrespective of the initial cell density. In summary, E. faecalis is capable of withstanding prolonged periods of starvation in a minimal metabolic state provided that there is a high cell density at the onset of starvation. Starved cells were capable of recovery upon addition of human serum.     

Inactivation of local root canal medicaments by dentine: an in vitro study

AIMS: The aim of the study was to investigate the inactivation by dentine of the antibacterial activity of various commonly used local root canal medicaments. METHODOLOGY: The medicaments tested were saturated calcium hydroxide solution, 1% sodium hypochlorite, 0.5% and 0.05% chlorhexidine acetate, and 2/4% and 0.2/0.4% iodine potassium iodide. Dentine was sterilized by autoclaving and crushed into powder with a particle size of 0.2-20 microns. Aliquots of dentine suspension were incubated with the medicaments in sealed test tubes at 37 degrees C for 24 h or 1 h before adding the bacteria. In some experiments bacteria were added simultaneously with dentine powder and the medicament. Enterococcus faecalis A197A was used as a test organism. Samples for bacterial culturing were taken from the suspensions at 5 min, 1 h and 24 h after adding the bacteria. RESULTS: Dentine powder had an inhibitory effect on all medicaments tested. The effect was dependent on the concentration of the medicament as well as on the length of the time the medicament was preincubated with dentine powder before adding the bacteria. The effect of calcium hydroxide on E. faecalis was totally abolished by the presence of dentine powder. Similarly, 0.2/0.4% iodine potassium iodide lost its effect after preincubation for 1 h with dentine before adding the bacteria. The effect of 0.05% chlorhexidine and 1% sodium hypochlorite on E. faecalis was reduced but not totally eliminated by the presence of dentine. No inhibition could be measured when full strength solutions of chlorhexidine and iodine potassium iodide were used in killing E. faecalis. CONCLUSIONS: The dentine powder model appears to be an efficient tool for the study of interactions between local endodontic medicaments, dentine, and microbes.     

Recovery of Enterococcus faecalis from cheese in the oral cavity of healthy subjects

INTRODUCTION: Enterococci are rarely found in the healthy human oral cavity, yet they are strongly associated with filled root canals. The origin of these enterococci remains unknown. Our hypothesis is that they are transient food-born colonizers under healthy conditions. This pilot study reinvestigated the prevalence of enterococci in the oral cavity of healthy volunteers, screened cheese samples for enterococci and investigated colonization of the oral cavity after ingestion of an enterocci-positive cheese. METHOD: Concentrated oral rinse samples were collected from a cohort of 50 dental students and proved negative for viable enterococci. Twenty cheese samples were obtained from local supermarkets. Enterococci were cultured and identified using standard methods. RESULTS: Viable enterococci were detected in one of five specimens of Swiss Tilsiter, three of five samples of French soft cheese, one of five Mozzarella samples and one of five Feta samples. Eight volunteers from the cohort consumed 10 g of a cheese with high Enterococcus faecalis load. Oral rinse samples were collected before and 1, 10 and 100 min after cheese ingestion. One minute after ingestion, a median of 5,480 E. faecalis colony-forming units was recovered from the oral rinse samples. Bacterial counts were reduced after 10 min, had dropped after 100 min to levels that were significantly (P < 0.005) different from the 1-min and 10-min scores and were below the detection limit after 1 week. CONCLUSIONS: These findings suggest that colonization of the healthy oral cavity by enterococci is transitional, but at the same time add weight to our hypothesis that enterococcal root canal infections could be food-borne.     

17%乙二胺四乙酸冲洗液对牙本质粪肠球菌黏附的影响

目的 研究17%乙二胺四乙酸（EDTA）冲洗液对促进牙本质粪肠球菌黏附的影响。方法 将48例半劈样本及12例牙本质片样本随机分为3个实验组和1个对照组,实验组分别经17%EDTA处理1、3、5 min,对照组经生理盐水处理5 min,接种粪肠球菌后通过扫描电子显微镜、激光共聚焦电子显微镜（CLSM）、菌落形成单位及组织学方法进行细菌黏附量的评价。结果 除组织学革兰染色显示,1 min组与对照组、3 min组的细菌侵入深度无明显差异（P>0.05）外,其余结果显示,实验组细菌生物膜厚度、侵入牙本质小管深度（CLSM测量）及菌落计数均大于对照组,差异具有统计学意义（P<0.05）;3个实验组之间比较,差异也具有统计学意义（P< 0.05）。结论 17%EDTA冲洗液可促进粪肠球菌对牙本质的黏附,且黏附量随处理时间的延长而增加。