生长环境对结核分枝杆菌胁迫作用的研究进展

高传染性结核病是由结核分枝杆菌引起的慢性消耗性疾病,病死率较高,备受全球关注。结核分枝杆菌是一种胞内寄生菌,通过呼吸道感染宿主,感染期间寄居肺部形成肉芽肿。肉芽肿或者免疫系统施加的环境压力,比如低pH、缺乏营养(缺铁)、缺氧等使结核分枝杆菌进入休眠状态,从而影响结核分枝杆菌的正常生长和抗生素的疗效。结核病治疗周期长,易产生耐药性,因此迫切需要研发新的药物以提升治疗效果。本文通过3个主要具有胁迫作用的生长环境因素综述了近年来发现的结核分枝杆菌相关调控因子和药物新靶点,为疫苗研究及新药物设计提供理论基础和研究依据。     

结核分枝杆菌快速检测中的新技术

结核分枝杆菌体外培养生长缓慢的特性和耐多药性给传统的实验室检测和药物敏感试验带来很多麻烦,从而给结核病的诊断和治疗增加困难,随着现代实验技术的发展,分子生物学技术,色谱技术以及计算机等技术在该菌中的研究和应用已显示出极大的优势,不仅能够快速鉴定到其种和株的水平,还能够提供快速的药敏试验的结果和考核抗结核治疗的效果,并可进行耐药基因的分析及分子流行病学调查,为人类最终控制并战胜结核病提供了有效的手段。     

微量元素对结核分枝杆菌生长的影响

本文报道了25种微量元素在改良罗氏培养基上对分枝杆菌菌株H,,Ra和BcG生长的促进作用。试验结果表明：N,、B、Mo、Cr、Zn、Se、Be等元素能显著地促进菌株的生长。Sr、Cu,Al、Si等元素也在一定程度上促进菌株的生长。培养基的pH值对微量元素的这种生长促进作用有一定影响。Zn、M。与草酸铵组合,对分枝杆菌菌株H,,Ra和BoG在酸性培养基上的初生长和后生长,均有明显的促进作用。而Co、Cu和Mn组合能部分地消除高pH值对分枝杆菌生长的抑制作用o N,和se有使分枝杆菌斜面培养物保持细胞和菌落完整的作用。     

结核分枝杆菌耐药性快速检测的研究进展

结核病的发展情况目前有增加的趋势,尤其是获得性免疫缺陷综合征(AIDS)出现以后.结核分枝杆菌(MTb)的耐药性或多重耐药性显然是结核病发病率增高、病死率升高的主要原因之一.     

快速方法检测结核分枝杆菌耐药基因突变

快速准确地鉴定结核分枝杆菌与结核分枝杆菌对利福平和异烟肼耐药基因突变的快速检测,对结核病人的诊断与治疗具有重要指导意义。本次根据结核分枝杆菌标准株H37RV序列,利用覆盖rpoB、katG、inhA基因突变区的系列寡核苷酸探针,并检测临床样品中结核分枝杆菌的基因突变情况,以此来判断耐药结果,并对其进行方法学评价。     

结核分枝杆菌滤过型的初步研究

目的研究结核分枝杆菌滤过型的生物学特性与检测方法。方法菌阴肺结核患者的结核分枝杆菌及其L型的液体培养物经0.45μm滤膜过滤后,涂片观察细菌形态,滤液分别进行分枝杆菌及其L型培养,并采用荧光基因定量法进行结核菌DNA检测。培养物用免疫组化染色鉴定,并采用透射电镜观察。结果30例痰、血滤前、滤后FQ-PCR检测同时阳性为53%,同时阴性为13%,滤前、滤后FQ-PCR结果符合率为67%。滤过后液体培养9例涂片见少许抗酸颗粒或椭圆性球菌。透射电镜见细胞壁缺失的"致密体"样细菌和细胞壁缺如菌。结论菌阴肺结核痰及血培养物中存在结核菌滤过型,滤过型携带遗传信息并可自我复制,采用生物学方法可以对其进行检测。     

建立液相芯片方法检测鉴别结核分枝杆菌复合群、鸟分枝杆菌与副结核分枝杆菌

运用液相芯片技术原理,以分枝杆菌菌种(群)特异基因序列IS6110、IS1081、IS1245和F57为目标基因,设计筛选4套扩增引物和杂交探针,建立同时检测鉴别结核分枝杆菌复合群、鸟分枝杆菌和副结核分枝杆菌的四重液相基因芯片检测方法。对13种共54株分枝杆菌菌株以及23种常见微生物样品的检测结果显示,四重液相芯片方法可特异检测鉴别目标菌种(群),与其它分枝杆菌菌种或微生物无非特异交叉反应;检测敏感性达2.1×101-2.5×102基因拷贝或0.06-0.74 fg DNA;组内检测变异系数和组间检测变异系数均<10%。采用四重液相芯片方法从临床结核疑似人痰样和牛组织样品中检出结核致病菌,检出率分别达75.6%(99/131)和94.9%(37/39),显著高于培养法(38.9%和53.8%)。对副结核疑似临床样品的检测试验结果显示,四重液相芯片方法与荧光PCR方法的阳性符合率为83%(24/29)。对四重混合模板的检测试验结果显示该液相芯片方法可鉴别不同菌种混合感染。四重液相芯片方法的检测周期<1 d,其中对纯化DNA模板的检测时间可在2-3 h内完成。     

分枝杆菌全合成琼脂培养基的研究

本文报道了一种适合常见致病分枝杆菌生长的全合成固体琼脂培养基体系。它为实验室研究分枝杆菌的营养生理、生化特性、遗传变异、药理和耐药机制提供了一种新工具,也为研制更加满意的分枝杆菌培养基创造了条件。试验过的大多数非典型分枝杆菌,在全合成琼脂培养基上比在罗氏培养基上生长快,生长量少于或等于罗氏培养基。标准牛型株的细胞群体中,仅有少量细胞能在全合成琼脂培养基上生长。鸟型．胞内和偶发等分枝杆菌标准株在全合成琼脂培养基上产生两种不同的菌落。     

分枝杆菌简化琼脂培养基的研究

报道三种组分简单、制备方便的简化琼脂培养基.试验结果表明:7个标准菌株在简化琼脂培养基309A和309C上的生长速度和数量均相似或优于改良罗氏培养基和92号土豆汤琼脂培养基.简化琼脂培养基309C和309A可用于结核杆菌分离和药敏试验.     

Molecular detection, identification and drug resistance detection in Mycobacterium tuberculosis

This minireview presents recent developments in molecular methods for the diagnosis of tuberculosis, including detection, identification and determination of drug resistance of Mycobacterium tuberculosis . Tuberculosis remains one of the major causes of global death from a single infectious agent. This situation is worsened by the HIV/AIDS pandemic because one-third of HIV/AIDS patients are coinfected with M. tuberculosis . Also of great concern is the emergence of drug-resistant tuberculosis because there are almost no treatment options available for patients affected by highly resistant strains of M. tuberculosis . Advances in molecular biology techniques and a better knowledge of the molecular mechanisms of drug resistance have provided new tools for the rapid diagnosis of tuberculosis. Several nucleic acid amplification technologies have been developed and evaluated. New molecular approaches are being introduced continuously. This minireview will also comment on the future perspectives for the molecular diagnosis of tuberculosis and the feasibility for the implementation of these newer techniques in the clinical diagnostic laboratory.     

Tuberculosis patients co-infected with Mycobacterium bovis and Mycobacterium tuberculosis in an urban area of Brazil

In this cross-sectional study, mycobacteria specimens from 189 tuberculosis (TB) patients living in an urban area in Brazil were characterised from 2008-2010 using phenotypic and molecular speciation methods (pncA gene and oxyR pseudogene analysis). Of these samples, 174 isolates simultaneously grew on Löwenstein-Jensen (LJ) and Stonebrink (SB)-containing media and presented phenotypic and molecular profiles of Mycobacterium tuberculosis, whereas 12 had molecular profiles of M. tuberculosis based on the DNA analysis of formalin-fixed paraffin wax-embedded tissue samples (paraffin blocks). One patient produced two sputum isolates, the first of which simultaneously grew on LJ and SB media and presented phenotypic and molecular profiles of M. tuberculosis, and the second of which only grew on SB media and presented phenotypic profiles of Mycobacterium bovis. One patient provided a bronchial lavage isolate, which simultaneously grew on LJ and SB media and presented phenotypic and molecular profiles of M. tuberculosis, but had molecular profiles of M. bovis from paraffin block DNA analysis, and one sample had molecular profiles of M. tuberculosis and M. bovis identified from two distinct paraffin blocks. Moreover, we found a low prevalence (1.6%) of M. bovis among these isolates, which suggests that local health service procedures likely underestimate its real frequency and that it deserves more attention from public health officials.     

Polymorphisms of 20 regulatory proteins between Mycobacterium tuberculosis and Mycobacterium bovis

Mycobacterium tuberculosis and Mycobacterium bovis are responsible for tuberculosis in humans and animals, respectively. Both species are closely related and belong to the Mycobacterium tuberculosis complex (MTC). M. tuberculosis is the most ancient species from which M. bovis and other members of the MTC evolved. The genome of M. bovis is over >99.95% identical to that of M. tuberculosis but with seven deletions ranging in size from 1 to 12.7 kb. In addition, 1200 single nucleotide mutations in coding regions distinguish M. bovis from M. tuberculosis. In the present study, we assessed 75 M. tuberculosis genomes and 23 M. bovis genomes to identify non‐synonymous mutations in 202 coding sequences of regulatory genes between both species. We identified species‐specific variants in 20 regulatory proteins and confirmed differential expression of hypoxia‐related genes between M. bovis and M. tuberculosis.     

A host-vector system for molecular study of the intracellular growth of Mycobacterium tuberculosis in phagocytic cells

The mechanisms by which Mycobacterium tuberculosis survives and persists in phagocytic cells remain poorly understood. To study the question, a convenient and safe host-vector system is indispensable. In this study it has been shown that, in contrast with M . smegmatis strain mc²155 which has been widely used for molecular analysis, M. smegmatis strain J15cs is able to survive even at day 6 post-infection in a murine macrophage cell line, J774. The survivability of J15cs was found to depend on the culture medium used for the bacteria prior to infection. Bacteria precultured on nutrient agar medium showed a high survivability and a characteristic cell wall ultrastructure. A plasmid vector, pYT923hyg, was developed from an Escherichia coli - mycobacterium shuttle vector pYT923 (previously constructed in our laboratory) to obtain three drug resistant genes (amp-, hyg- and km-resistant gene) and cloning sites in the km resistant gene. The vector pYT923hyg exerted no influence on in vitro growth of J15cs and intracellular survival in J774 cells, and was stably retained in J15cs after serial subculturing (three subcultures) in Luria-Bertani broth and at day 5 post-infection into J774 cells. Furthermore, using this system, the possibility of a relationship between some seemingly essential genes of M. tuberculosis and intracellular growth was demonstrated.
In this study, M. smegmatis strain J15cs and pYT923hyg were found to be capable of serving as an appropriate host-vector system for molecular study of the intracellular growth of M . tuberculosis in phagocytic cells; this system may be useful as a screening tool for M . tuberculosis genes.     

牛分支杆菌与肺结核分支杆菌基因组的比较

通过比较基因组学的方法研究发现,牛分支杆菌与肺结核杆菌基因组的同源性为99．95％,但在牛分枝杆菌基因组中有11个缺失区,大小从1kb到12．7kb,遗传信息的缺失引起牛分枝杆菌的基因组减小;牛分枝杆菌与肺结核分枝杆菌H37Rv间存在着2437个单核苷酸多态性（SNPs）,与肺结核分枝杆菌CDC1551间存在着2423个单核苷酸多态性（SNPs）,牛分支杆菌与肺结核分枝杆菌在编码细胞壁和分泌蛋白上变异程度也是巨大的。研究结果揭示了牛分支杆菌与肺结核分枝杆菌的遗传关系,为研究分支杆菌疫苗和诊断试剂提供理论依据,对牛肺结核病的防治有着非常重要的意义。     

结核分枝杆菌的致病机理

结核病仍是全球健康的主要威胁,其致病菌结核分枝杆菌的致闰机理与众不同。脂类代谢在致病中具有重要的作用。巨噬细胞被入侵的细菌修的机理也是研究细菌持续感染致病的重要突破点,研究细菌的致病机理可以为开发新的疫苗和治疗药物奠定坚实的基础。     

结核分枝杆菌重要诊断用抗原研究进展

血清学试验是结核诊断的重要依据。随着科学技术的进步,新的结核诊断用抗原不断被发现。我们简要综述了结核菌素蛋白衍生物、抗原85复合体、38kDa磷酸盐转运蛋白、6kDa早期分泌性蛋白、10kDa培养滤液蛋白、免疫性蛋白MPT64、主要分泌性免疫蛋白MPB70、表面脂蛋白MPB83等8种结核分枝杆菌重要抗原作为结核诊断用抗原的研究进展。     

三磷酸腺苷发光法快速检测结核分枝杆菌药敏技术的研究

目的 建立一种利用三磷酸腺苷( ATP) 与荧光素酶反应测定结核分枝杆菌( 简称结核杆菌) 释放的ATP 来判断结核杆菌药敏的技术。方法 ATP 生物发光法( 简称ATP 法) 通过裂解液体培养基中的结核杆菌, 释放活菌中的ATP, 加入荧光素酶使之发光以检测结核杆菌的活性。共采用H37Rv 标准株和10 株临床分离菌株, 用ATP 法与BACTEC 3D 法同步平行进行利福平药敏检测, 连续7 d 检测结核杆菌释放的ATP, 观察其生长曲线, 并以此判断对药物的敏感性。结果 在生长5 ～7 d的培养基中ATP法可以检测到敏感菌释放的ATP, 并且显著高于耐药菌所释放的ATP, 通过与BACTEC 3D 法相比确定其判断药敏的临界值, 检测结果与L-J 法及同步平行的BACTEC 3D 法对照组符合率达100% 。结论 ATP法可用于结核杆菌对抗结核药物敏感性的检测, 且因其价格较低, 无放射性元素的存在, 作为一种新型的结核杆菌药敏检测技术具有巨大的临床应用潜力。     

结核分枝杆菌与巨噬细胞相互作用的研究进展

结核分枝杆菌（Mycobacterium tuberculosis,MTB）是一种典型的胞内致病菌,巨噬细胞是MTB在体内的主要宿主细胞。巨噬细胞具有强大的吞噬功能,在机体固有免疫和适应性免疫中均发挥着重要作用,可有效保护宿主免受结核分枝杆菌的感染。MTB在与宿主巨噬细胞的长期相互作用过程中,逐渐形成多种逃避杀灭的有效策略,得以在宿主体内存活并增殖。该文从巨噬细胞抗MTB感染及MTB逃避巨噬细胞杀灭两个方面综述国内外的研究进展。