肠道杆菌和弧菌实用教案

1、第1页/共56页第一页，共57页。The Enterobacteriaceae are a large heterogenous group of gram-negative rods whose natural habitat is the intestinal tract of humans and animals.The family includes about 29 genera, over 100 species:EscherichiaShigellaSalmonellaCitrobacterKlebsiella Enterobacter 肠杆菌属Yersinia 克雷伯氏菌属 柠

2、檬酸细菌(xjn)属 耶尔森氏菌属 第2页/共56页第二页，共57页。Some of the enteric bacilli (., Escherichia coli) are part of the normal flora and major causing agent of opportunistic infection.Salmonellae and Shigellae are pathogenic for humans.第3页/共56页第三页，共57页。General characteristicsAll bacilli belonging to Enterobacteriaceae

3、 are short Gram-negative rods, either mobile or non-mobile, no spore, some have capsules and pili. Size: 0.4 X 3 m第4页/共56页第四页，共57页。General characteristicsAll bacilli belonging to Enterobacteriaceae are facultative anaerobes or aerobes. They grow in common media. Most of the enteric bacilli form circ

4、ular, gray, smooth colonies with distinct edges.第5页/共56页第五页，共57页。Mechanism: Non-pathogenic enteric bacilli are able to ferment lactose while pathogenic enteric bacilli such as Shigella and Salmonella are not.Basic components: lactose and a pH indicator第6页/共56页第六页，共57页。yesnoUse to differentiate non-p

5、athogenic E.Coli from pathogenic Shigella and Salmonella -SS agar plate第7页/共56页第七页，共57页。Double sugar iron agar slants: contains glucose, lactose, iron acetate 醋酸(c sun)亚铁 and pH indicator. Results:+-第8页/共56页第八页，共57页。General characteristicsEnterobacteriaceae have complex antigenic structuresH (flagel

6、lar) Agsomatic O Ag (lipopolysaccharide)K/Vi (capsular) Ag第9页/共56页第九页，共57页。General characteristics第10页/共56页第十页，共57页。Escherichia coli 大肠(dchng)埃希菌第11页/共56页第十一页，共57页。 Gram negative bacillus Motile with flagella Red colonies on SS agar medium most strains ferment lactose production of acid and gas with

7、in 2448h Antigens: O-Ag, H-Ag, K-Ag IMViC: + + 第12页/共56页第十二页，共57页。Flagella: induce adhesion Cytotoxic enterotoxins: cause diarrhea (sometimes with blood) and tissue damage.Invasion factors: permit invasion of bacteria into mucosa.第13页/共56页第十三页，共57页。PathogenesisInfections outside of intestines (cause

8、d by bacterial translocation 寄居部位(bwi)改变) 第14页/共56页第十四页，共57页。E.coli associated urinary tract infectionE.coli causes urinary tract infections such as acute cystitis 急性膀胱炎and nephritis肾炎.第15页/共56页第十五页，共57页。PathogenesisInfections inside of intestines: Gastroenteritis 肠胃炎, diarrhea 腹泻(fxi) caused by Pat

9、hogenic . 第16页/共56页第十六页，共57页。Enterotoxigenic E. coli (ETEC)肠产毒型It causes diarrhea similar to cholera but much milder in degree. They can cause travellers diarrhea“ and diarrhea in infant.Two types of plasmid-encoded toxins are produced. a) Heat labile toxins (LT): 不耐热(nai r)肠毒素 similar to cholera to

10、xin (see cholera section below) b) Heat stable toxins (ST):耐热(nai r)肠毒素 Clinical signs of caused disease are watery diarrhea, fever and nausea 头晕.第17页/共56页第十七页，共57页。Enteroinvasive E. coli (EIEC)肠侵袭(qnx)型It is commonly found associated with elder children and adult diarrhea， with no production of ent

11、erotoxins， infect and grow in the enterocytes.Morphologically, it is a Shigella-like without flagella. A very small number of EIEC can cause serious illness (high virulence). Acute inflammatory response 炎症(ynzhng)反应 and tissue destruction produce diarrhea with little fluid, much blood and mucus 脓血便。

12、第18页/共56页第十八页，共57页。Enteropathogenic E. coli (EPEC)肠致病型It is commonly found associated with infant diarrhea， no production of enterotoxins, no invasiveness. There is a characteristic morphological lesion with destruction of microvilli 微绒毛 without invasion of the organism, suggesting importance of bac

13、terial adhesion. Clinical signs: fever, watery diarrhea with and non-bloody stools, vomiting 呕吐(u t) and nausea.第19页/共56页第十九页，共57页。EHEC produces exotoxin. The illness is characterized by serious abdominal pain 腹痛(f tn) and diarrhea which is initially watery but then becomes bloody. In children, the

14、disease may be progressed to a systemic stage called as hemolytic uremic syndrome 溶血性尿毒综合征 (kidney injury) with 10% death rate.Enterohemorrhagic E. coli (EHEC)肠出血型(xuxng)第20页/共56页第二十页，共57页。 It causes a persistent, mucus-watery diarrhea with vomiting and dehydration in infants. It produces enteroaggr

15、egative heat-stable toxin. It produces mucous associated autoagglutinin自体凝集素 which causes aggregation of the bacteria at the cell surface as well as formation of biofilm 生物膜. Enteroaggregative E.coli (EAggEC) 肠聚集(jj)型 第21页/共56页第二十一页，共57页。第22页/共56页第二十二页，共57页。第23页/共56页第二十三页，共57页。According to the diffe

16、rence of O antigen, Shigella strains are divided into 4 groups: S. dysenteriae 痢疾(l ji)志贺菌 S. flexneri 福氏志贺菌 S. boydii 鲍氏志贺菌 S. sonnei 宋内志贺菌第24页/共56页第二十四页，共57页。Morphology and identificationGram-negative bacilli，no spore and capsule non-motile (without flagella) non-fermentation of lactoseMotility Te

17、st（-）（+）antigenic structures: 第25页/共56页第二十五页，共57页。第26页/共56页第二十六页，共57页。 Shigella is the most common of bacteria to cause bacterial dysentery 细菌性痢疾 in human with characteristic blood and mucus stools. Shigella only invades intestinal mucosa and never enters bloodstream 不入血. The endotoxin can be absorb

18、ed into bloodstream to cause endotoxemia 内毒素症. Toxic dysentery: In children, Shigella infection can cause systemic toxic symptoms 全身毒性(d xn)症状. Children suffering from toxic dysentery display a high death rate. 第27页/共56页第二十七页，共57页。Systemic toxic symptoms Abdominal cramps, diarrhea, fever, and bloody

19、 stools第28页/共56页第二十八页，共57页。 Prevention of fecal-oral transmission is the most effective control strategy. Dysentery is treated with antibiotics. But multiple drug resistance mediated by plasmids are common in many Shigella strains. Vaccines are not currently available.第29页/共56页第二十九页，共57页。第30页/共56页第三

20、十页，共57页。 Gram negative bacilli, with pili, no spore, no capsule (but with slime capsule) motile with flagella Non-fermentation of lactose antigenic structures: More than 2000 serotypes based on antigenic difference第31页/共56页第三十一页，共57页。consisted of capsular polysaccharide. It resists phagocytosis and

21、plays an important role during invasion of Salmonella.fever, toxic syndrome, shock, enteric inflammationwatery diarrhea第32页/共56页第三十二页，共57页。Human and many different animals can be carried or infected with . can survive in gall bladder because of its bile resistance and establish chronic carriage. 第33

22、页/共56页第三十三页，共57页。Enteric fever (typhoid fever) 肠热症(r zhn)Food-poisoning 肠胃炎（食物中毒）Septicemia 败血症第34页/共56页第三十四页，共57页。Enteric fever / typhoid fever第35页/共56页第三十五页，共57页。 Enteric fever / typhoid fever is the most serious form of salmonella infection which only occurs in human. Carrying state of the microb

23、es in human is common so that one carrier can cause a lot of spread. In untreated patients, the death rate is from 7% to 14%.Antibiotic therapy is essential, vaccines are not widely effective and not generally used.第36页/共56页第三十六页，共57页。living storehouses and factories of disease and human culture tub

24、es. Typhoid MaryA healthy carrier of typhoid who by this time had already infected numerous people through her cooking.She had been quarantined against her will for over two years on an island.第37页/共56页第三十七页，共57页。The microbe initially invades intestinal mucosal epithelium and propagate in the local.

25、 The microbe penetrates into the bloodstream to cause the first bacteremia 菌血症 with symptoms of fever, general discomfort and pain. The microbe enters many organs such as liver, spleen 脾, kidney 肾脏(shnzng), gall bladder 胆囊and marrow for further propagation. The microbe penetrates into the bloodstrea

26、m again to cause the second bacteremia with serious symptoms of high fever, swell of spleen and liver, rose-colored spots in skin, and tissue injury. (Major pathogenic factors: Vi antigen and endotoxin)第38页/共56页第三十八页，共57页。第39页/共56页第三十九页，共57页。rose-colored spots in skinEnteric fever第40页/共56页第四十页，共57页。

27、Gastroenteritis and septicemia 第41页/共56页第四十一页，共57页。 Gastroenteritis (food poisoning): It is the most common Salmonella infections and usually transmitted from contaminated food. However, only a few of food poisoning-causing salmonella serotypes can produce enterotoxin. Septicemia: Many Salmonella se

28、rotypes can cause septicemia. This disease is commonly found in children or adult with low immunity. 第42页/共56页第四十二页，共57页。Laboratory Diagnosis1. Specimen collection of enteric fever: In the first week, blood is collected as samples because of the first bacteremia. From the second week on, stool and u

29、rine are collected as samples because of effluence of the bacteria from stool and urine. 第43页/共56页第四十三页，共57页。2. Widal testDefinition: a agglutination test using the known O and H antigens of to detect specific serum antibodies. 第44页/共56页第四十四页，共57页。ii. Vibrio cholerae (Cholera 霍乱(hulun) 第45页/共56页第四十五

30、页，共57页。 Cholera caused by Vibrio cholerae is characterized by profuse watery diarrhea and serious vomiting which resulting in extreme loss of fluid and electrolytes 电解质, shock and kidney prostration 肾衰竭. If patients are untreated, the death rate is as high as 60%. Cholera remains a major global epid

31、emic disease. There have been 8 great outbreaks in the world. *In 1991, a great outbreak (7th) started in Peru. More than a million patients were found in Central and South America. *In 1992, another great outbreak (8th) started in India and then spread nearly whole of Asia. Not the typical serogrou

32、p O1 but the serogroup O139, a new found cholera pathogen caused this outbreak.第46页/共56页第四十六页，共57页。Cholera: outbreak in India 第47页/共56页第四十七页，共57页。第48页/共56页第四十八页，共57页。V. cholerae are highly motile, Gram-negative, curved 弧形 or comma-shaped 逗点(dudin)状 rods with a single polar flagellum 单鞭毛, no spore.第4

33、9页/共56页第四十九页，共57页。Characteristically, can grow in media with very high pH () and are rapidly killed by acid.Catalase positive, Indole test positive 第50页/共56页第五十页，共57页。B. Pathogenicityvirulent factors clinical findings 第51页/共56页第五十一页，共57页。Major virulent factors of Flagellum: offers an ability to pene

34、trate enteric mucus layer to reach the surface of host cells. Pilus: offers an ability to adhere host cells.Cholera toxin (enterotoxin): the most important virulent factor which inducing the electrolyte and water hypersecretion 过度(gud)分泌 of host cells. This toxin is chromosomally encoded and its molecule contains subunits A and B. 第52页/共56页第五十二页，共57页。 Pathogeni