醫(yī)學微生物學：第9章 弧菌屬

1、第九章 弧菌屬(Vibrio)第一節(jié) 霍亂弧菌第二節(jié) 副溶血性弧菌弧菌屬（Vibrio）細菌是一大群菌體短小，彎曲成弧形、一端有單鞭毛的革蘭陰性菌，運動極活潑。分布廣泛，多存在于水中。對人有致病性主要為霍亂弧菌(V. cholerae)和副溶血弧菌(V. parahaemolyticus )。第一節(jié) 霍亂弧菌霍亂弧菌（V.cholera）是人類霍亂的病原體?；魜y是一種古老且流行廣泛的烈性傳染病之一。曾在世界上引起多次大流行，主要表現(xiàn)為劇烈的嘔吐，腹瀉，失水，死亡率甚高。屬于國際檢疫傳染病。 中華人民共和國國境衛(wèi)生檢疫法第一章 總 則第三條 本法規(guī)定的傳染病是指檢疫傳染病和監(jiān)測傳染病。檢疫傳染病

2、，是指鼠疫、霍亂、黃熱病以及國務院確定和公布的其他傳染病。監(jiān)測傳染病，由國務院衛(wèi)生行政部門確定和公布。History and spread of epidemic choleraCholera has smoldered in an endemic fashion on the Indian subcontinent for centuries.There are references to deaths due to dehydrating diarrhea dating back to Hippocrates and Sanskrit writings. The mode of trans

3、mission of cholera by water was proven in 1849 by John Snow, a London physician. In 1883, Robert Koch successfully isolated the cholera vibrio from the intestinal discharges of cholera patients and proved conclusively that it was the agent of the disease.Vibrio cholerae O1 has two biotypes, namely,

4、classical and El Tor. The first long-distance spread of cholera to Europe and the Americas began in 1817, such that by the early 20th century, six waves of cholera had spread across the world in devastating epidemic fashion. Since then, until the 1960s, the disease contracted, remaining present only

5、 in southern Asia. In 1961, the El Tor biotype (distinguished from classic biotypes by the production of hemolysins) reemerged and produced a major epidemic in the Philippines to initiate a seventh global pandemic. Since then, this biotype has spread across Asia, the Middle East, Africa, and parts o

6、f Europe. There are several characteristics of the El Tor strain that confer upon it a high degree of epidemic virulence allowing it to spread across the world as previous strains have done. First, the ratio of cases to carriers is much less than in cholera due to classic biotypes (1: 30-100 for El

7、Tor vs. 1: 2 - 4 for classic biotypes). Second, the duration of carriage after infection is longer for the El Tor strain than the classic strains. Third, the El Tor strain survives for longer periods in the extraintestinal environment. Between 1969 and 1974, El Tor replaced the classic strains in th

8、e heartland of endemic cholera, the Ganges River Delta of India. Differences in whole-genome expression patterns between the classical and El Tor biotypes of Vibrio cholerae O1 were determined under conditions that induce virulence gene expression in the classical biotype. A total of 524 genes (13.5

9、% of the genome) were found to be differentially expressed in the two biotypes. The expression of genes encoding proteins required for biofilm formation, chemotaxis, and transport of amino acids, peptides, and iron was higher in the El Tor biotype. These gene expression differences may contribute to

10、 the enhanced survival capacity of the El Tor biotype in environmental reservoirs. The expression of genes encoding virulence factors was higher in the classical than in the El Tor biotype. A large fraction (20.8%) of the genes that are differentially expressed in the classical versus the El Tor bio

11、type are controlled by VieA in the classical biotype. Thus, VieA is a major regulator of genes in the classical biotype under virulence gene-inducing conditions. Sinem Beyhan, Anna D. Tischler, Andrew Camilli, and Fitnat H. Yildiz. Differences in Gene Expression between the Classical and El Tor Biot

12、ypes of Vibrio cholerae O1.Infection and Immunity, June 2006, p. 3633-3642, Vol. 74, No. 6霍亂弧菌的疫源地霍亂是一種烈性腸道傳染病，有3個疫源地： 印度恒河三角洲：O1群, 古典生物型：前六次世界性大流行，始于1817年； 印尼蘇拉威西島：O1群, 埃托生物型(EL-Tor bio-type) ：第七次世界大流行，始于1961年，累及140多個國家； 孟加拉灣（O139，Bengal）：始于1992年，危害相同。WHO規(guī)定：疑為霍亂病例，三種同時檢測。V cholerae O139 appears to

13、have been derived from the pandemic El Tor biotype but has lost the characteristic O1 somatic antigen; it has gained the ability to produce a polysaccharide capsule; it produces the same cholera enterotoxin; and it seems to have retained the epidemic potential of O1 strains. Last cholera outbreak da

14、tes December 2006 in Angola The physical map of the two replicons of classical V. cholerae strain 395. The circles represent the I-CeuI (Inner) and SfiI (Outer) maps. The order of genes within each SfiI fragment are arbitrary. (A) Replicon I. (B) Replicon II.Proc Natl Acad Sci U S A. 1998 November 2

15、4; 95(24): 1446414469. 一、生物學性狀形態(tài)染色G弧菌，單鞭毛，穿梭樣動力，魚群狀排列，有菌毛，個別有莢膜，無芽胞培養(yǎng)特性兼性厭氧，氧氣充分生長良好；營養(yǎng)要求不高，故用pH8-9堿性培養(yǎng)基，耐堿不耐酸（pH7.4-9.6），形成光滑透明濕潤的“水滴樣”菌落，分離（選擇）能在無鹽培養(yǎng)基中生長（區(qū)別其它弧菌）?；魜y弧菌在硫代硫酸鈉-檸檬酸鈉-膽鹽-蔗糖(TCBS)瓊脂平板上的生長狀況霍亂弧菌發(fā)酵蔗糖產(chǎn)酸，菌落呈黃色 生化反應：觸酶、氧化酶（+），硝酸鹽還原（+），靛基質(zhì)（+）抗原分型： 有200多個血清群，其中O1群、O139群可引起霍亂，其余不致病或僅引起胃腸炎等， O1群包

16、括兩個生物型：古典生物型和埃托生物型（E1-Tor）抵抗力：較弱怕干干燥時易死亡，水環(huán)境中可存活兩周（水源性傳 播，水性爆發(fā)）怕酸正常胃酸4min不耐熱100，1-2min對消毒劑、抗生素敏感。Antigenic Variation in V choleraeAntigenic variation plays an important role in the epidemiology and virulence of cholera. The flagellar antigens of V. cholerae are shared with many water vibrios and the

17、refore are of no use in distinguishing strains causing epidemic cholera. O antigens do distinguish strains of V. cholerae into 139 known serogroups. There are three distinct O1 serotypes, named Ogawa, Inaba and Hikojima, and each serotype may display the classical or El Tor biotypes. The Bengal stra

18、in (O139) is a new serological strain with a unique O-antigen which partly explains the lack of residual immunity. 二、致病性與免疫性致病物質(zhì)侵襲力鞭毛與黏液素酶鞭毛運動 有利于細菌穿過黏膜表面黏液層黏液素酶液化黏液菌毛使細菌定植于小腸霍亂腸毒素最強烈的致瀉毒素其致病機制與ETEC的LT相似，但作用強烈得多霍亂腸毒素的作用機制霍亂腸毒素的作用機制毒素由A和B兩個亞單位組成，A亞單位又分為A1和A2兩個肽鏈，兩者依靠二硫鏈連接。A亞單位為毒性單位，其中A1肽鏈具有酶活性，A2肽鏈與B

19、亞單位結(jié)合參與受體介導的內(nèi)吞作用中的轉(zhuǎn)位作用。B亞單位為結(jié)合單位，能特異地識別腸上皮細胞上的受體。1個毒素分子由一個A亞單位和5個B亞單位組成多聚體?；魜y腸毒素作用于腸細胞膜表面上的受體（由神經(jīng)節(jié)苷脂GM1組成），其B亞單位與受體結(jié)合，使毒素分子變構(gòu)，A精致單位進入細胞，A1肽鏈活化，進而激活腺苷環(huán)化酶（AC），使三磷酸腺苷（ATP）轉(zhuǎn)化為環(huán)磷酸腺苷（cAMP），細胞內(nèi) cAMP濃度增高，導致腸粘膜細胞分泌功能大為亢進，使大量體液和電解質(zhì)進入腸腔而發(fā)生劇烈吐瀉，由于大量脫水和失鹽，可發(fā)生代謝性酸中毒，血循環(huán)衰竭，甚至休克或死亡。 所致疾病霍亂（甲類法定傳染病02）傳染源：病人糞便污染的水源或食

20、品傳染途徑：經(jīng)口（暴飲暴食者）潛伏期：23d前驅(qū)期：不明顯，少數(shù)有輕度吐瀉、腹脹不適吐瀉期：劇烈吐瀉、米泔樣，每日數(shù)十次，持續(xù)23天，失水12000ml脫水期：嚴重吐瀉引起水電解質(zhì)紊亂，脫水酸中毒，腎衰、循環(huán)衰竭、休克、死亡。表現(xiàn)：神志不安、淡漠“霍亂面容”呈脫水貌，眼窩下陷，舟狀腹，肌痙攣等?；謴推冢和聻a停止、紊亂糾正、癥狀消失、病程平均為37天。免疫力：病人愈后可獲得牢固免疫。三、微生物學檢查與防治 烈性傳染?。òl(fā)病率高、流行迅速、死亡率高），早期、快速、準確診斷（尤其首例）對防治蔓延意義重大。1.標本：“米泔樣”便及嘔吐物，專人護送，快速送檢，指定實驗室；2.直接涂片鏡檢 懸滴法或暗視野顯微鏡，觀察穿梭樣運動；3.分離培養(yǎng)鑒定；4.快速診斷：熒光菌球法，SPA協(xié)同凝集試驗。免疫熒光菌球法 將糞標本直接接種于蛋白胨水中，此胨水中含有標記熒光素的O1群或O139群抗體，于37孵育46小時，此后或直接取培養(yǎng)液，或經(jīng)離心后取沉淀物作標本在熒光顯微鏡下觀察。如看到熒光菌球，表示試驗陽性，可作可疑診斷。SPA協(xié)同凝集試驗基本原理 由于SPA能與IgG的Fc片段非特異性結(jié)合，同時不影響Fab片段的活性,所以當帶有SPA的金黃色葡萄球菌與抗體混合，再