笔记肠道杆菌和弧菌课件

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1、笔记肠道杆菌和弧菌1i.Enteric 肠道的 Gram-Negative Rods&ii.Vibrio cholerae 霍乱弧菌笔记肠道杆菌和弧菌2i.Enteric Gram-Negative Rods (Enterobacteriaceae 肠杆菌)笔记肠道杆菌和弧菌3The Enterobacteriaceae are a large heterogenous group of gram-negative rods whose natural habitat is the intestinal tract of humans and animals.The family includ

2、es about 29 genera,over 100 species:EscherichiaShigellaSalmonellaCitrobacterKlebsiella Enterobacter 肠杆菌属Yersinia 克雷伯氏菌属 柠檬酸细菌属 耶尔森氏菌属 笔记肠道杆菌和弧菌4Some of the enteric bacilli(e.g.,Escherichia coli)are part of the normal flora and major causing agent of opportunistic infection.Salmonellae and Shigellae

3、are pathogenic for humans.笔记肠道杆菌和弧菌5General characteristicsAll bacilli belonging to Enterobacteriaceae are short Gram-negative rods,either mobile or non-mobile,no spore,some have capsules and pili.Size:0.4 X 3 m笔记肠道杆菌和弧菌6General characteristicsAll bacilli belonging to Enterobacteriaceae are facultat

4、ive anaerobes or aerobes.They grow in common media.Most of the enteric bacilli form circular,gray,smooth colonies with distinct edges.笔记肠道杆菌和弧菌7lactose fermentation乳糖发酵Mechanism:Non-pathogenic enteric bacilli are able to ferment lactose while pathogenic enteric bacilli such as Shigella and Salmonell

5、a are not.Basic components:lactose and a pH indicator 笔记肠道杆菌和弧菌8lactose fermentation Results yesnoUse to differentiate non-pathogenic E.Coli from pathogenic Shigella and Salmonella-SS agar plate笔记肠道杆菌和弧菌9 Double sugar iron agar slants:contains glucose,lactose,iron acetate 醋酸亚铁 and pH indicator.Resul

6、ts:hydrogen sulfide(H2S)+-lactose fermentation笔记肠道杆菌和弧菌10General characteristicsEnterobacteriaceae have complex antigenic structuresH(flagellar)Agsomatic O Ag(lipopolysaccharide)K/Vi(capsular)Ag笔记肠道杆菌和弧菌11General characteristicsCommon pathogenic materials for Enterobacteriaceae include:bacterial str

7、uctures(flagella,capsules)toxins(enterotoxin,endotoxin)笔记肠道杆菌和弧菌12Escherichia coli 大肠埃希菌笔记肠道杆菌和弧菌13Morphology and identification Gram negative bacillus Motile with flagella Red colonies on SS agar medium most strains ferment lactose production of acid and gas within 2448h Antigens:O-Ag,H-Ag,K-Ag IMV

8、iC:+笔记肠道杆菌和弧菌14Transmission is by fecal-oral route.Virulence factors include:Flagella:induce adhesion Cytotoxic enterotoxins:cause diarrhea(sometimes with blood)and tissue damage.Invasion factors:permit invasion of bacteria into mucosa.Pathogenesis笔记肠道杆菌和弧菌15PathogenesisInfections outside of intesti

9、nes(caused by bacterial translocation 寄居部位改变)Opportunistic infection including septicemia 败血症,pneumonia 肺炎,meningitis 脑膜炎 and urinary tract infections 泌尿系统感染笔记肠道杆菌和弧菌16E.coli associated urinary tract infectionE.coli causes urinary tract infections such as acute cystitis 急性膀胱炎and nephritis肾炎.笔记肠道杆菌和弧

10、菌17PathogenesisInfections inside of intestines:Gastroenteritis 肠胃炎,diarrhea 腹泻 caused by Pathogenic E.coli.笔记肠道杆菌和弧菌18Enterotoxigenic 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

11、 toxins are produced.a)Heat labile toxins(LT):不耐热肠毒素 similar to cholera toxin(see cholera section below)b)Heat stable toxins(ST):耐热肠毒素 Clinical signs of caused disease are watery diarrhea,fever and nausea 头晕.笔记肠道杆菌和弧菌19Enteroinvasive E.coli(EIEC)肠侵袭型It is commonly found associated with elder childre

12、n and adult diarrhea，with no production of enterotoxins，infect and grow in the enterocytes.Morphologically,it is a Shigella-like E.coli without flagella.A very small number of EIEC can cause serious illness(high virulence).Acute inflammatory response 炎症反应 and tissue destruction produce diarrhea with

13、 little fluid,much blood and mucus 脓血便。笔记肠道杆菌和弧菌20Enteropathogenic 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,sug

14、gesting importance of bacterial adhesion.Clinical signs:fever,watery diarrhea with and non-bloody stools,vomiting 呕吐 and nausea.笔记肠道杆菌和弧菌21EHEC produces exotoxin.The illness is characterized by serious abdominal pain 腹痛 and diarrhea which is initially watery but then becomes bloody.In children,the d

15、isease 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)肠出血型笔记肠道杆菌和弧菌22 It causes a persistent,mucus-watery diarrhea with vomiting and dehydration in infants.It produces enteroaggregative heat-stable tox

16、in.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)肠聚集型 笔记肠道杆菌和弧菌23Sanitary 卫生的 significance Total bacterial number:The number of bacteria contained per ml or per mg of

17、the sample,and the standard for drinking water is less than 100 bacteria.Coliform bacteria index大肠杆菌指数:The number of coliform bacteria contained per 1000 ml of the sample,and the standard for drinking water is less than 3.笔记肠道杆菌和弧菌24Shigella 志贺菌笔记肠道杆菌和弧菌25ClassificationAccording to the difference of

18、 O antigen,Shigella strains are divided into 4 groups:S.dysenteriae 痢疾志贺菌 S.flexneri 福氏志贺菌 S.boydii 鲍氏志贺菌 S.sonnei 宋内志贺菌笔记肠道杆菌和弧菌26Morphology and identification Gram-negative bacilli，no spore and capsule non-motile(without flagella)non-fermentation of lactoseMotility Test（-）（+）On regular agar plate:

19、Medium size,smooth,semitransparent coloniesantigenic structures:O and K antigens笔记肠道杆菌和弧菌27Pathogenic factors pili endotoxin：fever，toxic shock,inflammation response,ulcer,bloody stool,abdominal pain exotoxin:Shigella dysenteriae can produce an exotoxin called as shiga-toxin 志贺毒素.Shiga-toxin is enter

20、otoxic,cytotoxic and neurotoxic.So the dysentery caused by this microbe is more serious than that by the other three groups.笔记肠道杆菌和弧菌28Clinical findings 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 invade

21、s intestinal mucosa and never enters bloodstream 不入血.The endotoxin can be absorbed into bloodstream to cause endotoxemia 内毒素症.Toxic dysentery:In children,Shigella infection can cause systemic toxic symptoms 全身毒性症状.Children suffering from toxic dysentery display a high death rate.笔记肠道杆菌和弧菌29Systemic

22、toxic symptoms Abdominal cramps,diarrhea,fever,and bloody stools笔记肠道杆菌和弧菌30 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 curren

23、tly available.Control笔记肠道杆菌和弧菌31Salmonella 沙门菌属 笔记肠道杆菌和弧菌32Gram negative bacilli,with pili,no spore,no capsule(but with slime capsule)motile with flagellaNon-fermentation of lactoseantigenic structures:O,H and Vi antigens (More than 2000 serotypes based on antigenic difference)Morphology and identif

24、ication笔记肠道杆菌和弧菌33Pathogenic factorsVi antigen:consisted of capsular polysaccharide.It resists phagocytosis and plays an important role during invasion of Salmonella.Endotoxin:fever,toxic syndrome,shock,enteric inflammationEnterotoxin:watery diarrhea笔记肠道杆菌和弧菌34DiseasesHuman and many different animal

25、s can be carried or infected with Salmonella.Salmonella can survive in gall bladder because of its bile resistance and establish chronic carriage.笔记肠道杆菌和弧菌35DiseasesEnteric fever(typhoid fever)肠热症Food-poisoning 肠胃炎（食物中毒）Septicemia 败血症笔记肠道杆菌和弧菌36Enteric fever/typhoid fever笔记肠道杆菌和弧菌37 Enteric fever/ty

26、phoid fever is the most serious form of salmonella infection which only occurs in human.Carrying state of the microbes 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 effect

27、ive and not generally used.笔记肠道杆菌和弧菌38living storehouses and factories of disease and human culture tubes.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.笔记肠道杆

28、菌和弧菌39The microbe initially invades intestinal mucosal epithelium and propagate in the local.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,gall bladder 胆

29、囊and marrow for further propagation.The microbe penetrates into the bloodstream 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)Disease development笔记肠道杆菌

30、和弧菌40笔记肠道杆菌和弧菌41rose-colored spots in skinEnteric fever笔记肠道杆菌和弧菌42Gastroenteritis and septicemia 笔记肠道杆菌和弧菌43 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 ca

31、n produce enterotoxin.Septicemia:Many Salmonella serotypes can cause septicemia.This disease is commonly found in children or adult with low immunity.笔记肠道杆菌和弧菌44Laboratory Diagnosis1.Specimen collection of enteric fever:In the first week,blood is collected as samples because of the first bacteremia.

32、From the second week on,stool and urine are collected as samples because of effluence of the bacteria from stool and urine.笔记肠道杆菌和弧菌452.Widal testDefinition:a agglutination test using the known O and H antigens of S.typhi to detect specific serum antibodies.笔记肠道杆菌和弧菌46ii.Vibrio cholerae(Cholera 霍乱)笔

33、记肠道杆菌和弧菌47General indroduction of cholera 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%.Chole

34、ra remains a major global epidemic 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 t

35、he typical serogroup O1 but the serogroup O139,a new found cholera pathogen caused this outbreak.笔记肠道杆菌和弧菌48Cholera:outbreak in India 笔记肠道杆菌和弧菌49A.Biological characteristics笔记肠道杆菌和弧菌50V.cholerae are highly motile,Gram-negative,curved 弧形 or comma-shaped 逗点状 rods with a single polar flagellum 单鞭毛,no s

36、pore.Morphology of typical organisms笔记肠道杆菌和弧菌51CultureCharacteristically,V.cholerae can grow in media with very high pH(pH8.5-9.0)and are rapidly killed by acid.Catalase positive,Indole test positive O and H antigensAntigenic structures 笔记肠道杆菌和弧菌52B.Pathogenicity virulent factors clinical findings 笔

37、记肠道杆菌和弧菌53Major virulent factors of V.choleraeFlagellum:offers an ability to penetrate 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 hypersecre

38、tion 过度分泌 of host cells.This toxin is chromosomally encoded and its molecule contains subunits A and B.笔记肠道杆菌和弧菌54 Pathogenic mechanism of cholera toxin Subunit B binds to its receptor on the surface of epithelial cells and provides a channel for allowing subunit A to enter host cell.笔记肠道杆菌和弧菌55Dehy

39、dration is the major reason for death.So replacement of fluid plus electrolyte is most important during the treatment.Antibiotic therapy is additionally used.Vaccination 疫苗预防 is only partially effective and not generally recommended.It is most commonly used by international travelers.C.Control笔记肠道杆菌

40、和弧菌56 SummaryThe most important contents in this lecture:General introduction:1)the significance of lactose fermentation;2)the categories of major antigens of enterobacteriaceae.E.coli:1)lactose fermentation;2)different antigens Shigella:the major virulent factors Salmonella:1)bile resistant;2)the developing process of typhoid fever and the associated virulent factors;Vibrio:1)V.cholerae grows in high pH media;2)virulent factor:cholera toxin