PPT课件肠道杆菌PPT课件PPT课件

1、肠杆菌科目前有44个菌属、170多个种。多为肠道正常菌群，但可成为条件致病菌；少数为致病菌。第1页/共31页A. All bacilli belonging to Enterobacteriaceae are short gram-negative rods, either mobile or non-mobile. 第2页/共31页B. All bacilli belonging to Enterobacteriaceae are facultative anaerobes. They grow in common media. Most of the enteric bacilli for

2、m round, convex, smooth colonies with distinct edges.第3页/共31页Mechanism: Non-pathogenic enteric bacilli can ferment lactose while pathogenic enteric bacilli such as Shigella and Salmonella can not.Media: SS-plate or EMB plate , TSI agar slantsBasic components: lactose and a pH indicatorC. The identif

3、ication of Enterobacteriaceae is largely depend on biochemical reactions第4页/共31页SS plate第5页/共31页D. Enterobacteriaceae have complex antigenic structures.H Ag (flagella) somatic O Ag (lipopolysaccharide)K/Vi Ag (capsule) 第6页/共31页第7页/共31页Infections outside the intestines caused by bacterial translocati

4、on Opportunistic infection including septicemia, pneumonia, meningitis and urinary tract infections Community-acquired infectionurinary tract infections第8页/共31页E. coli associated urinary tract infectionE. coli causes urinary tract infections such as acute cystitis（ 急 性 膀 胱 炎 ） a n d pyelonephritis（肾

5、盂肾炎）.第9页/共31页Infections inside the intestines caused by pathogenic E. coliCommon symptoms include Gastroenteritis（肠胃炎）, diarrhea（腹泻） and dysentery（痢疾）. Disease transmission is by fecal-oral route （粪口途径）.第10页/共31页Cause travellers diarrhea. Two types of plasmid-encoded toxins are produced: Heat labile

6、 toxins (LT/耐热肠毒素耐热肠毒素)activate adenyl cyclase（腺苷环化酶）（腺苷环化酶） which catalyze ATP to cAMP Heat stable toxins (ST/不耐热肠毒素不耐热肠毒素)activate guanyl cyclase（鸟苷环化酶）（鸟苷环化酶） to catalyze GTP to cGMP cAMP/cGMP are the intracellular second messagers. The former increases the secretion of water and ions, and the la

7、tter inhibits ionic uptake. Clinical signs: watery diarrhea, fever and nausea.第11页/共31页 Commonly associated with infant diarrhea. Characteristic lesion with destruction of microvilli without invasion Clinical signs: fever, diarrhea with non-bloody stools, vomiting and nausea.第12页/共31页第13页/共31页 Assoc

8、iated with elder children and adult diarrhea. Without flagella High virulence: a small number of EIEC can cause serious illness Clinical signs: Acute inflammatory responses and tissue destruction. Produce diarrhea with little fluid, much blood and mucus containing polymorphonuclear cells. 第14页/共31页E

9、HEC produces bacteriophage-mediated exotoxin. This toxin is called Vero toxin (VT) because of its cytotoxicity to cultured Vero cells. The illness is characterized by serious abdominal pain and diarrhea which is initially watery but then becomes bloody. In children, the disease may be progressed to

10、a systemic stage called as hemolytic uremic syndrome (kidney injury) with 10% death rate.第15页/共31页 A dominant serotype of EHEC is E. coli O157:H7 第16页/共31页 It causes a persistent, mucus-watery diarrhea with vomiting and dehydration in infants. It produces enteroaggregative heat-stable toxin (EAST) s

11、imilar to the heat stable toxins of ETEC. It produces mucous associated autoagglutinin which causes aggregation of the bacteria and formation of biofilm. 第17页/共31页E. coli Enterobacter AerogenesIMViC testIndole testMethyl red (MR) testVoges-Proskauer (VP) testCitrate utilization test枸橼酸盐试验吲哚试验甲基红试验产气

12、肠杆菌菌毛疫苗菌毛疫苗第18页/共31页QUIZ 1主要引起婴儿和旅行者腹泻的大肠埃希菌是：A.肠产毒型大肠埃希菌B.肠致病型大肠埃希菌C.肠侵袭型大肠埃希菌D.肠出血型大肠埃希菌第19页/共31页痢疾发病总数在前五位，死亡在前十位（传染病）革兰氏阴性短小杆菌，无鞭毛，有菌毛，无芽胞，无荚膜O抗原是分类依据，可以分为4群（种），40余个血清型（包括亚型）致病性：黏附、侵袭、胞内繁殖、细胞间扩散志贺菌属第20页/共31页 沙门菌属第21页/共31页 急性消化道传染病，我国乙类传染病急性消化道传染病，我国乙类传染病 Enteric fever (typhoid fever) is the most

13、 serious form of salmonella infection which only occurs in human Carrier state is common In untreated patients, the death rate is 7% to 14% Antibiotic therapy is essential, vaccines are not effective and not widely used第22页/共31页1.The microbe initially invades intestinal mucosal epithelium and propag

14、ate at the local. 2.The microbe penetrates into the bloodstream to cause the first round of bacteremia with symptoms of fever, general discomfort and pain. 3.The microbe enters many organs such as liver, spleen, kidney, gall and marrow for further propagation. 4.The microbe penetrates into the blood

15、stream again to cause the second round of bacteremia with serious symptoms of high fever, swell of spleen and liver, rose-colored spots in skin, and tissue injury.第23页/共31页1. 致病菌S. typhi （伤寒沙门菌）S. paratyphi A （甲型副伤寒杆菌）S. schottmuelleri （肖式沙门菌）S. hirschfeldii （希式沙门菌）enteric fever Diagnosis 2. 标本采集 Bl

16、ood first week Stool and urine from the second week on Marrow can be considered because of its high and permanent positive results.第24页/共31页enteric fever diagnosis3. Widal test （肥达试验）（肥达试验）a quantitative agglutination test using the known O antigen of S.typhi , and H antigens of S. typhi and S. para

17、typhi A/B to detect specific serum antibodies. For one single serum sample, The titers of anti-O antigen IgM 1:80 and/or anti-H antigen IgG 1:160. For two serum samples that collected with an interval of 57 days, 4-fold increase in titers of specific antibody.第25页/共31页急性胃肠炎(食物中毒，Gastroenteritis /foo

18、d-poisoning)败血症It is the most common Salmonella infection and usually transmitted from contaminated food. However, only a few of food poisoning-causing salmonella serotypes can produce enterotoxin.Many Salmonella serotypes can cause septicemia. This disease is commonly found in children or adult with low immunity.第26页/共31页QUIZ 2肠热症发病一周内，进行病原性诊断应选择：A.尿培养B.血培养C.粪便培养D