醫(yī)學微生物學：第11章 分枝桿菌屬

1、第十三章 分枝桿菌屬 (Mycobacterium)第一節(jié) 結核分枝桿菌第二節(jié) 麻風分枝桿菌第三節(jié) 其他分支桿菌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分枝桿菌屬(Mycobacteri

6、um): 是一類細長略彎曲的桿菌，因繁殖時有分枝生長趨勢而得名。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 特點:細胞壁含有大量的脂類菌體不易著色，但加溫或延長染色時間著色后能抵抗鹽酸乙醇的脫色，故采用抗酸染色，

10、故又稱抗酸桿菌(acid- fast bacilli)無特殊結構，致病與菌體成分有關，形成慢性肉芽腫性病變營養(yǎng)要求高，生長緩慢可分為三大類： 結核分枝桿菌 麻風分枝桿菌 非結核分枝桿菌 (非典型分枝桿菌) 第一節(jié) 結核分枝桿菌結核分枝桿菌(M. tuberculosis)俗稱結核桿菌(tubercle bacilli): 為結核病的病原體。 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、生物學性狀 形態(tài)染色菌體細長微彎，有時呈分枝狀排列不規(guī)則，多單個散在無特殊結構抗酸染色陽性L型抗酸染色陰性而革蘭染色陽性培養(yǎng)特性專性需氧，溫度37，pH偏酸6.56.8營養(yǎng)要求高，羅氏(Lowenstein)培養(yǎng)基（蛋黃、甘油、天門冬素、馬鈴薯、無機鹽、孔雀綠等）生長緩慢，18h分裂一次，24W形成R型菌落，“菜花樣菌落”，乳白色干燥不透明，表面呈顆粒結節(jié)，邊緣不整齊

14、生化反應不發(fā)酵糖類觸酶試驗陽性熱觸酶試驗陰性抵抗力強抗干燥，抗酸堿，抗化學消毒劑；對濕熱和紫外線敏感；對抗結核藥（異煙肼、利福平、環(huán)絲氨酸 、乙胺丁醇等）敏感，但易產(chǎn)生耐藥性。變異性：結核桿菌多種性狀可發(fā)生變異形態(tài)變異：在異煙肼、溶菌酶等作用下形成L型（多形性）；菌落變異：R-S型變異，性狀典型不典型，毒力減弱；毒力變異：卡介苗（Bacilli Calmette-Guerin, BCG）： 1908年兩位科學家將有毒的牛型分枝桿菌接種在含甘油、膽汁、馬鈴薯的培養(yǎng)基中，經(jīng)13年230代傳代獲得的減毒菌株，即卡介苗沿用至今；耐藥菌株。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 結核桿菌無侵襲性酶，不含內(nèi)毒素也不產(chǎn)生外毒素，其致病性主要由于:菌體成分細菌繁殖引起炎癥代謝產(chǎn)物毒性作用抗體對菌體成分產(chǎn)生免疫病理損傷致病物質(zhì)-菌體成分 脂質(zhì)-存在細胞壁，占細胞壁干重的60%,含量與毒力平行，包括磷脂、脂肪酸和蠟質(zhì)：索狀因子(cord factor)（糖脂分枝菌酸+海藻糖）磷脂蠟質(zhì)D（分枝菌酸+肽糖脂）硫酸腦苷脂作用：引起結核結節(jié)，慢性肉芽腫及組織細胞干酪樣壞死等病變。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 毒力成分組成作用索狀因子(cord factor)糖脂分枝菌酸+海藻糖破壞線粒體膜，影響呼吸，抑制白細胞游走引起慢性肉芽腫磷脂刺激單核細胞增生，病灶結核結節(jié)和干酪樣壞死蠟質(zhì)D(wax-D)分枝菌酸+肽糖脂引起動物遲發(fā)型超敏反應，具免疫佐劑作用硫酸腦苷脂抑制吞噬體與溶酶體的融合毒力成分及其作用致病物質(zhì)-菌體成分蛋白質(zhì)有抗原性、本身無毒，如結核菌素蛋白質(zhì)+蠟質(zhì)D-遲發(fā)型變態(tài)反應組織壞死、全身中毒癥狀結核

18、結節(jié)形成分枝菌生長素（mycobactin）可溶性鐵螯合物多糖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.所致疾病傳染源：開放性肺結核病人痰傳播途徑：呼吸道、消化道、皮膚黏膜所致疾病肺部感染（1）原發(fā)感染常見兒童（外源性感染）結局機體抵抗力強

19、形成結核結節(jié)纖維化鈣化自愈（但病灶內(nèi)常有細菌的潛伏）機體抵抗力差 活動性肺結核干酪樣壞死 全身播散粟粒樣結核肺泡滲出性炎癥（原發(fā)灶）肺門淋巴結（腫大）沿淋巴管擴散（炎癥）原發(fā)綜合癥（啞鈴型）特點：特異免疫沒有建立，故局部病變較輕，但易擴散（2）原發(fā)后感染（繼發(fā)感染）常見成人 （原發(fā)病灶內(nèi)源性感染） 特點：局部病變重，但不易擴散 一般局限于肺部，易發(fā)生干酪樣壞死，可形成空洞和開放性肺結核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 粟粒樣結核干酪樣壞死肺結核瘤 慢性纖維空洞性肺結核 肺外感染 腸結核，結核性腦膜炎，皮膚結核，腎結核，骨結核免疫性人體對該菌有較強免疫力（感染率高，發(fā)病率低）主要是細胞免疫（感染免疫或有菌免疫）細胞免疫與遲發(fā)型超敏反應并存柯赫現(xiàn)象(Koch phenomenon)-超敏反應給豚鼠按次接種一定量的結核菌，約1014天之后，注射局部發(fā)

24、生紅腫，逐漸形成潰瘍，經(jīng)久不愈，結核菌大量繁殖，到達局部淋巴結，并沿淋巴結及血液循環(huán)向全身播散，豚鼠易于死亡，表明豚鼠對結核菌無免疫力。 如將同量結核菌注入46周前已受少量結核菌感染的豚鼠體內(nèi)，動物高熱，23天之后，注射局部出現(xiàn)組織紅腫、潰瘍、壞死等劇烈反應，不久即可愈合、結痂、局部淋巴結并不腫大，不發(fā)生全身性結核播散，亦不致死亡。機體對結核菌再感染與初感染所表現(xiàn)出不同反應的現(xiàn)象，稱為科赫（Koch）現(xiàn)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、微生物檢查與防治 微生物學檢查直接涂片染色觀察，菌數(shù)少時需濃縮集菌染色鏡檢（抗酸染色法）分離培養(yǎng)動物實驗結核菌素皮膚試驗（tuberculin skin test）細菌核酸檢測結核菌素皮膚試驗原理：用結核菌素測定機體能否發(fā)生遲發(fā)性超敏反應，以判斷機體對結核有無免疫力試劑： 舊結核菌素（old tuber

26、culin, OT） 兩種 純蛋白衍生物（PPD）PPD-C，BCG-PPD方法：兩前臂皮下分別注射PPD-C, BCG-PPD各5單位，48-72h后觀察結果結果：紅腫硬結5mm，陽性 紅腫硬結 15mm，強陽性紅腫硬結5mm，陰性結核菌素皮膚試驗應用 選擇卡介苗的接種對象，并作為接種卡介苗后免疫效果評價的指標； 嬰幼兒結核病診斷的參考指標； 評價腫瘤患者非特異性細胞免疫功能的指標； 人群中結核菌感染的流行率調(diào)查。 意義陽性：已感染過/BCG接種成功，有免疫力強陽性：現(xiàn)在活動性結核陰性：未感染/未接種BCG假陰性：感染初期，老年人，嚴重結核合并其它傳染病使用免疫抑制劑艾滋病等免疫功能低下者四

27、、防治原則應用卡介苗預防接種治療原則：早期、大量、長期、聯(lián)合用藥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 第二節(jié) 麻風分枝桿菌（M.leprae） 一、生物學性狀 大小、形態(tài)、染色均與結核桿菌類似，但菌體略粗，多存在于細胞內(nèi)麻風細胞: 有大量麻風桿菌存在的感染細胞，稱泡沫細胞（foam cell）Massive gene decay in the

29、leprosy bacillus Nature 409, 1007-1011 (2001). 目前體外人工培養(yǎng)尚未成功動物模型：犰狳 ，對該菌高度易感，接種后引起瘤型麻風，人對該菌抵抗力強，接觸者僅少數(shù)發(fā)病。致病性 人類為唯一宿主和唯一傳染源，致病因素不清傳染源：病人（瘤型麻風病人通過皮膚黏膜及外分泌液向外排菌）傳播途徑：皮膚、黏膜、呼吸道及密切接觸傳播（家庭內(nèi)傳播多見）潛伏期：2-5年，長者數(shù)十年特點：潛伏期長，發(fā)病慢，病程長的慢性傳染病 麻風病變可分為四型： 瘤型麻風（lepromatous type）：惡性麻風侵犯部位：皮膚黏膜、神經(jīng)及內(nèi)臟 病變中大量麻風細胞傳染性強 分泌物中大量麻風桿

30、菌開放性麻風 細胞免疫缺陷（麻風菌素試驗陰性）免疫狀態(tài) 體液免疫正常（抗原抗體復合物沉積）病變：肉芽腫，麻風結節(jié)臨床表現(xiàn)：“獅面容”，病情嚴重，逐漸惡化。結核樣型麻風（tuberculoid）:良性麻風， 60-70%侵犯部位：皮膚、周圍神經(jīng)傳染性小病變處少見麻風細胞及麻風桿菌閉鎖性麻風免疫狀態(tài)：細胞免疫接近正常（麻風菌素試驗陽性）病變：淋巴細胞上皮樣細胞，巨噬細胞浸潤臨床表現(xiàn)： 皮膚邊緣清楚的紅色斑疹 由于細胞浸潤變粗、變硬可觸及 外周神經(jīng) 感覺功能障礙界線類(borderline form)：兼具兩者的特點未定類(indeterminate form)：前期病變麻風桿菌侵犯神經(jīng)系統(tǒng)Renal involvement in leprosy: retrospective analysis of 461 cases in Brazil. Braz J Infect Disvol.10no.2SalvadorApr.2006 微生物學檢查直接涂片，結合病史可診斷早期發(fā)現(xiàn)、早期隔離氨苯砜、利福平和氯苯吩嗪聯(lián)合用藥治療 第三節(jié) 其他分枝桿菌牛分枝桿菌非結核分枝桿菌：除結核桿菌、牛分枝桿菌和麻風桿菌以外的分枝桿菌。致病特點對人類致病力較弱；發(fā)生于防御功能下降時，作為繼發(fā)或伴隨性疾??；與結核分枝桿菌發(fā)生混合感染的主要是鳥-胞內(nèi)分枝桿菌；對一般抗結核藥物易產(chǎn)生耐藥性。結核分枝桿菌與非結核分枝桿