肠道杆菌和弧菌课件

1、肠道杆菌和弧菌（）Vibrio cholerae肠道杆菌和弧菌（）肠道杆菌和弧菌（）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 Enterobac

2、ter 肠杆菌属肠杆菌属Yersinia 克雷伯氏菌属克雷伯氏菌属 柠檬酸细菌属柠檬酸细菌属 耶尔森氏菌属耶尔森氏菌属 肠道杆菌和弧菌（）Some of the enteric bacilli (e.g., Escherichia coli) are part of the normal flora and major causing agent of opportunistic infection.Salmonellae and Shigellae are pathogenic for humans.肠道杆菌和弧菌（）General characteristicsAll bacilli be

3、longing 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肠道杆菌和弧菌（）General characteristicsAll bacilli belonging to Enterobacteriaceae are facultative anaerobes or aerobes. They grow in common media. Most of the ente

4、ric bacilli form circular, gray, smooth colonies with distinct edges.肠道杆菌和弧菌（）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肠道杆菌和弧菌（）yesnoUse to differentiate

5、non-pathogenic E.Coli from pathogenic Shigella and Salmonella -SS agar plate肠道杆菌和弧菌（）Double sugar iron agar slants: contains glucose, lactose, iron acetate 醋酸亚铁醋酸亚铁 and pH indicator.Results:+-肠道杆菌和弧菌（）General characteristicsEnterobacteriaceae have complex antigenic structuresH (flagellar) Agsomatic

6、O Ag (lipopolysaccharide)K/Vi (capsular) Ag肠道杆菌和弧菌（）General characteristics肠道杆菌和弧菌（）Escherichia coli 大肠埃希菌大肠埃希菌肠道杆菌和弧菌（） 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 IMViC: +

7、 + 肠道杆菌和弧菌（）Flagella: induce adhesion Cytotoxic enterotoxins: cause diarrhea (sometimes with blood) and tissue damage.Invasion factors: permit invasion of bacteria into mucosa.肠道杆菌和弧菌（）PathogenesisInfections outside of intestines(caused by bacterial translocation 寄居部位改变寄居部位改变) Opportunistic infectio

8、n including septicemia 败血症败血症, pneumonia 肺炎肺炎, meningitis 脑膜炎脑膜炎 and urinary tract infections 泌尿系泌尿系统感染统感染肠道杆菌和弧菌（）E.coli associated urinary tract infectionE.coli causes urinary tract infections such as acute cystitis 急性膀胱炎and nephritis肾炎.肠道杆菌和弧菌（）PathogenesisInfections inside of intestines: Gastroe

9、nteritis 肠胃炎肠胃炎, diarrhea 腹泻腹泻 caused by Pathogenic E.coli.肠道杆菌和弧菌（）Enterotoxigenic E. coli (ETEC)肠产毒型肠产毒型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 toxin

10、s (LT): 不耐热肠毒素不耐热肠毒素 similar to cholera toxin (see cholera section below) b) Heat stable toxins (ST):耐热肠毒素耐热肠毒素 Clinical signs of caused disease are watery diarrhea, fever and nausea 头晕头晕.肠道杆菌和弧菌（）Enteroinvasive E. coli (EIEC)肠侵袭型肠侵袭型It is commonly found associated with elder children and adult diar

11、rhea， 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 炎症反应炎症反应 and tissue destruction produce diarrhea with littl

12、e fluid, much blood and mucus 脓血便。脓血便。肠道杆菌和弧菌（）Enteropathogenic E. coli (EPEC)肠致病型肠致病型It is commonly found associated with infant diarrhea， no production of enterotoxins, no invasiveness. There is a characteristic morphological lesion with destruction of microvilli 微绒毛微绒毛 without invasion of the org

13、anism, suggesting importance of bacterial adhesion. Clinical signs: fever, watery diarrhea with and non-bloody stools, vomiting 呕吐呕吐 and nausea.肠道杆菌和弧菌（）EHEC produces exotoxin. The illness is characterized by serious abdominal pain 腹痛腹痛 and diarrhea which is initially watery but then becomes bloody.

14、 In children, the disease may be progressed to a systemic stage called as hemolytic uremic syndrome 溶血性尿毒综合征溶血性尿毒综合征 (kidney injury) with 10% death rate.Enterohemorrhagic E. coli (EHEC)肠出血型肠出血型肠道杆菌和弧菌（） It causes a persistent, mucus-watery diarrhea with vomiting and dehydration in infants. It produc

15、es enteroaggregative heat-stable toxin. It produces mucous associated autoagglutinin自体凝集素自体凝集素 which causes aggregation of the bacteria at the cell surface as well as formation of biofilm 生物膜生物膜. Enteroaggregative E.coli (EAggEC)肠道杆菌和弧菌（）Total bacterial number: The number of bacteria contained per m

16、l or per mg of the sample, and the standard for drinking water is less than 100 bacteria. Coliform bacteria index大肠杆菌指数大肠杆菌指数: The number of coliform bacteria contained per 1000 ml of the sample, and the standard for drinking water is less than 3.肠道杆菌和弧菌（）肠道杆菌和弧菌（）According to the difference of O an

17、tigen, Shigella strains are divided into 4 groups: 肠道杆菌和弧菌（）Morphology and identificationGram-negative bacilli，no spore and capsule non-motile (without flagella) non-fermentation of lactoseMotility Test（-）（+）antigenic structures: 肠道杆菌和弧菌（）fever，toxic shock, inflammation response, ulcer, bloody stool

18、, abdominal painShigella dysenteriae can produce an exotoxin called as shiga-toxin 志贺毒素志贺毒素. Shiga-toxin is enterotoxic, cytotoxic and neurotoxic. So the dysentery caused by this microbe is more serious than that by the other three groups.肠道杆菌和弧菌（） Shigella is the most common of bacteria to cause ba

19、cterial dysentery 细菌性痢疾细菌性痢疾 in human with characteristic blood and mucus stools. Shigella only invades intestinal mucosa and never enters bloodstream 不入血不入血. The endotoxin can be absorbed into bloodstream to cause endotoxemia 内毒素症内毒素症. Toxic dysentery: In children, Shigella infection can cause syst

20、emic toxic symptoms 全身毒性症状. Children suffering from toxic dysentery display a high death rate. 肠道杆菌和弧菌（）Systemic toxic symptoms Abdominal cramps, diarrhea, fever, and bloody stools肠道杆菌和弧菌（） Prevention of fecal-oral transmission is the most effective control strategy. Dysentery is treated with antibi

21、otics. But multiple drug resistance mediated by plasmids are common in many Shigella strains. Vaccines are not currently available.肠道杆菌和弧菌（） 肠道杆菌和弧菌（）Gram negative bacilli, with pili, no spore, no capsule (but with slime capsule)motile with flagellaNon-fermentation of lactoseantigenic structures: Mo

22、re than 2000 serotypes based on antigenic difference肠道杆菌和弧菌（）consisted of capsular polysaccharide. It resists phagocytosis and plays an important role during invasion of Salmonella.fever, toxic syndrome, shock, enteric inflammationwatery diarrhea肠道杆菌和弧菌（）Human and many different animals can be carri

23、ed or infected with . can survive in gall bladder because of its bile resistance and establish chronic carriage. 肠道杆菌和弧菌（）Enteric fever (typhoid fever) 肠热症肠热症Food-poisoning 肠胃炎（食物中毒）肠胃炎（食物中毒）Septicemia 败血症败血症肠道杆菌和弧菌（）Enteric fever / typhoid fever肠道杆菌和弧菌（） Enteric fever / typhoid fever is the most se

24、rious 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 effective and not generally

25、 used.肠道杆菌和弧菌（）living 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.肠道杆菌和弧菌（）The microbe initia

26、lly invades intestinal mucosal epithelium and propagate in the local. The microbe penetrates into the bloodstream to cause the first bacteremia 菌血症菌血症 with symptoms of fever, general discomfort and pain. The microbe enters many organs such as liver, spleen 脾脾, kidney 肾脏肾脏, gall bladder 胆囊胆囊and marro

27、w 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)肠道杆菌和弧菌（）肠道杆菌和弧菌（）rose-colore

28、d spots in skinEnteric fever肠道杆菌和弧菌（）Gastroenteritis and septicemia 肠道杆菌和弧菌（） 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. Sept

29、icemia: Many Salmonella serotypes can cause septicemia. This disease is commonly found in children or adult with low immunity. 肠道杆菌和弧菌（）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

30、on, stool and urine are collected as samples because of effluence of the bacteria from stool and urine. 肠道杆菌和弧菌（）2. Widal testDefinition: a agglutination test using the known O and H antigens of S.typhi to detect specific serum antibodies. 肠道杆菌和弧菌（）ii. Vibrio cholerae 肠道杆菌和弧菌（） Cholera caused by Vib

31、rio cholerae is characterized by profuse watery diarrhea and serious vomiting which resulting in extreme loss of fluid and electrolytes 电解质电解质, shock and kidney prostration 肾衰肾衰竭竭. If patients are untreated, the death rate is as high as 60%. Cholera remains a major global epidemic disease. There hav

32、e 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 serogroup O1 but the serogroup

33、O139, a new found cholera pathogen caused this outbreak.肠道杆菌和弧菌（）Cholera: outbreak in India 肠道杆菌和弧菌（）肠道杆菌和弧菌（）V. cholerae are highly motile, Gram-negative, curved 弧形弧形 or comma-shaped 逗点状逗点状 rods with a single polar flagellum 单鞭毛单鞭毛, no spore.肠道杆菌和弧菌（）Characteristically, V.cholerae can grow in media

34、 with very high pH (pH8.5-9.0) and are rapidly killed by acid.Catalase positive, Indole test positive 肠道杆菌和弧菌（）B. Pathogenicityvirulent factors clinical findings 肠道杆菌和弧菌（）Major 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