医学微生物学：第11章 分枝杆菌属

1、第十三章 分枝杆菌属 (Mycobacterium)第一节 结核分枝杆菌第二节 麻风分枝杆菌第三节 其他分支杆菌A 22-year-old gravid African-American woman was evaluated at 23 weeks gestation during her second pregnancy because of a positive tuberculin skin test result with 18 mm of induration. The patient reported a history of dry cough and fever for 2

2、months, and weight loss and night sweats for 1 month. She denied hemoptysis. The findings of her physical examination were unremarkable except for a body weight of 48 kg (body mass index, 18.3 kg/m2). On examination, her temperature was 42C. Breath sounds were normal, and there were no crackles, ral

3、es, or rhonchi. The patient was admitted to the hospital. The chest radiograph revealed a left upper lung cavity (Fig 1 ). Additional infiltrates could be seen in the entire left lung and in the right parahilar mid-lung field. Several concentrated sputum samples revealed numerous acid-fast bacilli.

4、Daily antituberculous therapy was initiated with rifampin, 600 mg, isoniazid, 300 mg, and ethambutol, 700 mg (with a target of 15 mg/kg). One smear-positive specimen was immediately processed for susceptibility testing after communicating with the mycobacteriology laboratory. After 3 weeks of treatm

5、ent, the patient continued to have a temperature of up to 39.4C and experienced a weight loss of about 5 kg. A repeat chest radiograph revealed a worsening of the left lung infiltrate and a persistence of the right-sided infiltrate. Fig 1 Initial chest radiograph of a pregnant woman分枝杆菌属(Mycobacteri

6、um): 是一类细长略弯曲的杆菌，因繁殖时有分枝生长趋势而得名。Scientific classificationKingdom:BacteriaPhylum:ActinobacteriaOrder:ActinomycetalesSuborder:CorynebacterineaeFamily:MycobacteriaceaeGenus:MycobacteriumThe classification-based upon cladistics 1 Slowly growing 1.1 Mycobacterium tuberculosis complex (MTBC) members are c

7、ausative agents of human and animal tuberculosis. 1.2 Mycobacterium avium complex (MAC), is a group of species which, in a disseminated infection but not lung infection, used to be a significant cause of death in AIDS patients. 1.3 Mycobacterium gordonae clade 1.4 Mycobacterium kansasii clade 1.5 My

8、cobacterium nonchromogenicum/terrae clade 1.6 Mycolactone-producing mycobacteria M. ulcerans, which causes the Buruli, or Bairnsdale, ulcer 1.7 Mycobacterium simiae clade 1.8 Ungrouped M. leprae, which causes leprosy 2 Intermediate growth rate 3 Rapidly growing 4 Ungrouped Mycobacterium tuberculosis

9、 complex (MTBC) members are causative agents of human and animal tuberculosis. Species in this complex include: M. tuberculosis, the major cause of human tuberculosis M. bovis M. bovis BCG M. africanum M. canetti M. caprae M. microti M. pinnipedii 特点:细胞壁含有大量的脂类菌体不易着色，但加温或延长染色时间着色后能抵抗盐酸乙醇的脱色，故采用抗酸染色，

10、故又称抗酸杆菌(acid- fast bacilli)无特殊结构，致病与菌体成分有关，形成慢性肉芽肿性病变营养要求高，生长缓慢可分为三大类： 结核分枝杆菌 麻风分枝杆菌 非结核分枝杆菌 (非典型分枝杆菌) 第一节 结核分枝杆菌结核分枝杆菌(M. tuberculosis)俗称结核杆菌(tubercle bacilli): 为结核病的病原体。 Tuberculosis comes from the Latin word, tuberculum, meaning protuberance, projection or growth, and refers to the tumor-like nod

11、ules that victims often display. In fact, until TBs bacterial agent was discovered in 1882, many physicians thought TBs characteristic nodules and wasting identified it as a form of cancer. Robert Koch (1843-1910)Tuberculosis incidence rate, 2004. Multi-drug resistant tuberculosis, 2004 distribution

12、 of proportion of MDR-TB among new TB cases, 1994-2009 / WHO Tuberculosis (TB) is the worlds leading infectious killer of young and middle-aged adults, causing 26 percent of avoidable deaths in the developing world. The Global Burden of Disease study places TB among the seven leading causes of lost

13、Disability-Adjusted Life Years (DALYs) well into the 21st century. -International Food Policy Research Institute 一、生物学性状 形态染色菌体细长微弯，有时呈分枝状排列不规则，多单个散在无特殊结构抗酸染色阳性L型抗酸染色阴性而革兰染色阳性培养特性专性需氧，温度37，pH偏酸6.56.8营养要求高，罗氏(Lowenstein)培养基（蛋黄、甘油、天门冬素、马铃薯、无机盐、孔雀绿等）生长缓慢，18h分裂一次，24W形成R型菌落，“菜花样菌落”，乳白色干燥不透明，表面呈颗粒结节，边缘不整齐

14、生化反应不发酵糖类触酶试验阳性热触酶试验阴性抵抗力强抗干燥，抗酸碱，抗化学消毒剂；对湿热和紫外线敏感；对抗结核药（异烟肼、利福平、环丝氨酸 、乙胺丁醇等）敏感，但易产生耐药性。变异性：结核杆菌多种性状可发生变异形态变异：在异烟肼、溶菌酶等作用下形成L型（多形性）；菌落变异：R-S型变异，性状典型不典型，毒力减弱；毒力变异：卡介苗（Bacilli Calmette-Guerin, BCG）： 1908年两位科学家将有毒的牛型分枝杆菌接种在含甘油、胆汁、马铃薯的培养基中，经13年230代传代获得的减毒菌株，即卡介苗沿用至今；耐药菌株。1:NASTA M.The appearance of L fo

15、rms in a Mycobacterium (Myco. phlei)Article in French. Rev Sci Med. 1962;7:83-6. 二、致病性和免疫性 结核杆菌无侵袭性酶，不含内毒素也不产生外毒素，其致病性主要由于:菌体成分细菌繁殖引起炎症代谢产物毒性作用抗体对菌体成分产生免疫病理损伤致病物质-菌体成分 脂质-存在细胞壁，占细胞壁干重的60%,含量与毒力平行，包括磷脂、脂肪酸和蜡质：索状因子(cord factor)（糖脂分枝菌酸+海藻糖）磷脂蜡质D（分枝菌酸+肽糖脂）硫酸脑苷脂作用：引起结核结节，慢性肉芽肿及组织细胞干酪样坏死等病变。海藻糖（Trehalose）

16、Mycolic acids the side chains (R1 and R2) vary in length according to the genus; C60 to C90 in Mycobacterium; C40 to C56 in Nocardia. The function of mycolic acids: Increase resistance to chemical damage and dehydration, Prevent the effective activity of hydrophobic antibiotics, Allow the bacterium

17、to grow readily inside macrophages, effectively hiding it from the hosts immune system.Cord Factor 毒力成分组成作用索状因子(cord factor)糖脂分枝菌酸+海藻糖破坏线粒体膜，影响呼吸，抑制白细胞游走引起慢性肉芽肿磷脂刺激单核细胞增生，病灶结核结节和干酪样坏死蜡质D(wax-D)分枝菌酸+肽糖脂引起动物迟发型超敏反应，具免疫佐剂作用硫酸脑苷脂抑制吞噬体与溶酶体的融合毒力成分及其作用致病物质-菌体成分蛋白质有抗原性、本身无毒，如结核菌素蛋白质+蜡质D-迟发型变态反应组织坏死、全身中毒症状结核

18、结节形成分枝菌生长素（mycobactin）可溶性铁螯合物多糖Mycobactin: a substance in some mycobacteria capable of promoting the growth of other mycobacteria; it is capable of extracting ferric ion from the medium which someMycobacteriumspp. are unable to do.所致疾病传染源：开放性肺结核病人痰传播途径：呼吸道、消化道、皮肤黏膜所致疾病肺部感染（1）原发感染常见儿童（外源性感染）结局机体抵抗力强

19、形成结核结节纤维化钙化自愈（但病灶内常有细菌的潜伏）机体抵抗力差 活动性肺结核干酪样坏死 全身播散粟粒样结核肺泡渗出性炎症（原发灶）肺门淋巴结（肿大）沿淋巴管扩散（炎症）原发综合症（哑铃型）特点：特异免疫没有建立，故局部病变较轻，但易扩散（2）原发后感染（继发感染）常见成人 （原发病灶内源性感染） 特点：局部病变重，但不易扩散 一般局限于肺部，易发生干酪样坏死，可形成空洞和开放性肺结核Primary tuberculosisUsually a respiratory infection that occurs in childhood Infection results in sub-pleu

20、ral Ghon focus and mediastinal lymphadenopathy Regarded as the primary complex Symptoms are often few Resolution of infection usually occurs complications include: Haematogenous spread causing miliary TB affecting lungs, bones, joints, meninges Direct pulmonary spread resulting in TB bronchopneumoni

21、a TuberculosisTuberculosisPost-primary tuberculosisOccurs in adolescence or adult life Due to reactivation of infection or repeat exposure Results in more significant symptoms Reactivation may be associated with immunosuppression (e.g. drugs or HIV infection) Pulmonary infection accounts for 70% of

22、cases of post-primary TB Usually affects apices of upper or lower lobes Cavitation of infection into the bronchial tree results in open TB Clinical features include cough, haemoptysis, malaise, weight loss and night sweats Infection of lymph glands results in discrete, firm and painless lymphadenopa

23、thy Confluence of infected glands can result in a cold abscess Infection of the urinary tract can cause haematuria and sterile pyuria 粟粒样结核干酪样坏死肺结核瘤 慢性纤维空洞性肺结核 肺外感染 肠结核，结核性脑膜炎，皮肤结核，肾结核，骨结核免疫性人体对该菌有较强免疫力（感染率高，发病率低）主要是细胞免疫（感染免疫或有菌免疫）细胞免疫与迟发型超敏反应并存柯赫现象(Koch phenomenon)-超敏反应给豚鼠按次接种一定量的结核菌，约1014天之后，注射局部发

24、生红肿，逐渐形成溃疡，经久不愈，结核菌大量繁殖，到达局部淋巴结，并沿淋巴结及血液循环向全身播散，豚鼠易于死亡，表明豚鼠对结核菌无免疫力。 如将同量结核菌注入46周前已受少量结核菌感染的豚鼠体内，动物高热，23天之后，注射局部出现组织红肿、溃疡、坏死等剧烈反应，不久即可愈合、结痂、局部淋巴结并不肿大，不发生全身性结核播散，亦不致死亡。机体对结核菌再感染与初感染所表现出不同反应的现象，称为科赫（Koch）现象。Kochs phenomenon Delayed hypersensititvity response. If an animal previously infected with tube

25、rculosis organisms is reinfected intracutaneously, a local inflammatory reaction marked by necrotic lesions will develop rapidly and heal quickly.三、微生物检查与防治 微生物学检查直接涂片染色观察，菌数少时需浓缩集菌染色镜检（抗酸染色法）分离培养动物实验结核菌素皮肤试验（tuberculin skin test）细菌核酸检测结核菌素皮肤试验原理：用结核菌素测定机体能否发生迟发性超敏反应，以判断机体对结核有无免疫力试剂： 旧结核菌素（old tuber

26、culin, OT） 两种 纯蛋白衍生物（PPD）PPD-C，BCG-PPD方法：两前臂皮下分别注射PPD-C, BCG-PPD各5单位，48-72h后观察结果结果：红肿硬结5mm，阳性 红肿硬结 15mm，强阳性红肿硬结5mm，阴性结核菌素皮肤试验应用 选择卡介苗的接种对象，并作为接种卡介苗后免疫效果评价的指标； 婴幼儿结核病诊断的参考指标； 评价肿瘤患者非特异性细胞免疫功能的指标； 人群中结核菌感染的流行率调查。 意义阳性：已感染过/BCG接种成功，有免疫力强阳性：现在活动性结核阴性：未感染/未接种BCG假阴性：感染初期，老年人，严重结核合并其它传染病使用免疫抑制剂艾滋病等免疫功能低下者四

27、、防治原则应用卡介苗预防接种治疗原则：早期、大量、长期、联合用药Multidrug resistant TB (MDR TB) is TB that is resistant to at least two first line therapies isoniazid and rifampin. Extensively drug-resistant TB (XDR TB) is TB resistant to at least isoniazid and rifampin among the first-line anti-TB drugs and among second-line drug

28、s, is resistant to any fluoroquinolone and at least one of three injectable drugs. Drug-resistant TB is difficult and costly to treat and can be fatal./od/oc/media/pressrel/2007 第二节 麻风分枝杆菌（M.leprae） 一、生物学性状 大小、形态、染色均与结核杆菌类似，但菌体略粗，多存在于细胞内麻风细胞: 有大量麻风杆菌存在的感染细胞，称泡沫细胞（foam cell）Massive gene decay in the

29、leprosy bacillus Nature 409, 1007-1011 (2001). 目前体外人工培养尚未成功动物模型：犰狳 ，对该菌高度易感，接种后引起瘤型麻风，人对该菌抵抗力强，接触者仅少数发病。致病性 人类为唯一宿主和唯一传染源，致病因素不清传染源：病人（瘤型麻风病人通过皮肤黏膜及外分泌液向外排菌）传播途径：皮肤、黏膜、呼吸道及密切接触传播（家庭内传播多见）潜伏期：2-5年，长者数十年特点：潜伏期长，发病慢，病程长的慢性传染病 麻风病变可分为四型： 瘤型麻风（lepromatous type）：恶性麻风侵犯部位：皮肤黏膜、神经及内脏 病变中大量麻风细胞传染性强 分泌物中大量麻风杆

30、菌开放性麻风 细胞免疫缺陷（麻风菌素试验阴性）免疫状态 体液免疫正常（抗原抗体复合物沉积）病变：肉芽肿，麻风结节临床表现：“狮面容”，病情严重，逐渐恶化。结核样型麻风（tuberculoid）:良性麻风， 60-70%侵犯部位：皮肤、周围神经传染性小病变处少见麻风细胞及麻风杆菌闭锁性麻风免疫状态：细胞免疫接近正常（麻风菌素试验阳性）病变：淋巴细胞上皮样细胞，巨噬细胞浸润临床表现： 皮肤边缘清楚的红色斑疹 由于细胞浸润变粗、变硬可触及 外周神经 感觉功能障碍界线类(borderline form)：兼具两者的特点未定类(indeterminate form)：前期病变麻风杆菌侵犯神经系统Renal involvement in leprosy: retrospective analysis of 461 cases in Brazil. Braz J Infect Disvol.10no.2SalvadorApr.2006 微生物学检查直接涂片，结合病史可诊断早期发现、早期隔离氨苯砜、利福平和氯苯吩嗪联合用药治疗 第三节 其他分枝杆菌牛分枝杆菌非结核分枝杆菌：除结核杆菌、牛分枝杆菌和麻风杆菌以外的分枝杆菌。致病特点对人类致病力较弱；发生于防御功能下降时，作为继发或伴随性疾病；与结核分枝杆菌发生混合感染的主要是鸟-胞内分枝杆菌；对一般抗结核药物易产生耐药性。结核分枝杆菌与非结核分枝杆