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肠道杆菌

肠道杆菌. Enterobacteriaceae ( 肠杆菌科 ). 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。. All bacilli belonging to Enterobacteriaceae are short gram-negative rods, either mobile or non-mobile.

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肠道杆菌

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  1. 肠道杆菌

  2. Enterobacteriaceae (肠杆菌科) • 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。

  3. All bacilli belonging to Enterobacteriaceaeare short gram-negative rods, either mobile or non-mobile.

  4. All bacilli belonging to Enterobacteriaceaeare facultative anaerobes. They grow in common media. Most of the enteric bacilli form round, convex, smooth colonies with distinct edges.

  5. The identification of Enterobacteriaceae is largely depend on biochemical reactions Lactose（乳糖） fermentation • 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 slants • Basic components:lactose and a pH indicator

  6. Results white colonies pathogenic/致病菌 red colonies non-pathogenic/非致病菌 SS plate

  7. Enterobacteriaceae have complex antigenic structures. H Ag (flagella) K/Vi Ag (capsule) somatic OAg(lipopolysaccharide)

  8. Common pathogenic materials for Enterobacteriaceae include: • bacterial structures (pili, capsule) • toxins (enterotoxin, endotoxin)

  9. Infections outside the intestines caused by bacterial translocation • Opportunistic infection • including septicemia, pneumonia, meningitis and urinary tract infections • Community-acquired infection • urinary tract infections

  10. E. coli causes urinary tract infections such as acute cystitis（急性膀胱炎） and pyelonephritis（肾盂肾炎）. E. coli associated urinary tract infection

  11. 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）. • Enterotoxigenic E. coli (ETEC/肠产毒性大肠杆菌) • Enteropathogenic E. coli (EPEC/肠致病性大肠杆菌) • Enteroinvasive E. coli (EIEC/肠侵袭型大肠杆菌) • Enterohemorrhagic E. coli (EHEC/肠出血性大肠杆菌) • Enteroaggregative E. coli (EAEC/肠集聚性大肠杆菌)

  12. Enterotoxigenic E. coli (ETEC/肠产毒性大肠杆菌) • Cause "traveller’s diarrhea". • Two types of plasmid-encoded toxins are produced: • Heat labile toxins (LT/耐热肠毒素) • activateadenyl cyclase（腺苷环化酶） which catalyze ATP to cAMP • Heat stable toxins (ST/不耐热肠毒素) • activate guanyl cyclase（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 latter inhibits ionic uptake. • Clinical signs: watery diarrhea,fever and nausea.

  13. Enteropathogenic E. coli (EPEC/肠致病性大肠杆菌) • Commonly associated with infant diarrhea. • Characteristic lesion with destruction of microvilli without invasion • Clinical signs: fever, diarrhea with non-bloody stools, vomiting and nausea.

  14. Enteroinvasive E. coli (EIEC/肠侵袭型大肠杆菌) • Associated 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.

  15. Enterohemorrhagic E. coli (EHEC/肠出血性大肠杆菌) • EHEC 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 a systemic stage called as hemolytic uremic syndrome (kidney injury) with 10% death rate.

  16. A dominant serotype of EHEC is E. coliO157:H7

  17. Enteroaggregative E. coli (EAEC/肠集聚性大肠杆菌) • It causes a persistent, mucus-watery diarrhea with vomiting and dehydration in infants. • It produces enteroaggregative heat-stable toxin (EAST) similar to the heat stable toxins of ETEC. • It produces mucous associated autoagglutinin which causes aggregation of the bacteria and formation of biofilm.

  18.         E. coli Enterobacter Aerogenes 微生物学检测 IMViC test Indole test 吲哚试验 Methyl red (MR) test 甲基红试验 Voges-Proskauer (VP) test Citrate utilization test 枸橼酸盐试验   产气肠杆菌 防治原则 菌毛疫苗

  19. QUIZ 1 • 主要引起婴儿和旅行者腹泻的大肠埃希菌是： • 肠产毒型大肠埃希菌 • 肠致病型大肠埃希菌 • 肠侵袭型大肠埃希菌 • 肠出血型大肠埃希菌

  20. Shigella 志贺菌属 • 人类细菌性痢疾的最常见病原菌 • （急性细菌性痢疾，慢性细菌性痢疾） • 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

  21. Salmonella 沙门菌属

  22. 肠热症 (伤寒、副伤寒) • 急性消化道传染病，我国乙类传染病 • Enteric fever (typhoid fever) is the most 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

  23. enteric fever development • The microbe initially invades intestinal mucosal epithelium and propagate at the local. • The microbe penetrates into the bloodstream to cause the first round of bacteremia with symptoms of fever, general discomfort and pain. • The microbe enters many organs such as liver, spleen, kidney, gall and marrow for further propagation. • The microbe penetrates into the bloodstream 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.

  24. enteric fever Diagnosis • 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） 2. 标本采集 Blood @ first week Stool and urine @ from the second week on Marrow can be considered because of its high and permanent positive results.

  25. enteric fever diagnosis • 3. Widal test （肥达试验） • a quantitative agglutination test using the known O antigen of S.typhi , and H antigens of S. typhi and S. paratyphiA/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 5~7 days, 4-fold increase in titers of specific antibody.

  26. 沙门菌引起的其它疾病 • 急性胃肠炎(食物中毒，Gastroenteritis /food-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.

  27. QUIZ 2 • 肠热症发病一周内，进行病原性诊断应选择： • 尿培养 • 血培养 • 粪便培养 • 肥达试验

  28. 幽门螺杆菌 Helicobacter pylori

  29. 慢性胃炎，消化性溃疡，胃癌 2005诺贝尔奖获得者Barry Marshall，Robin Warren于1983年，从胃炎组织标本中分离出幽门螺杆菌，并证实该菌是胃炎及消化道溃疡的病原菌

  30. 一端有2-6根鞭毛，运动活泼的革兰氏阴性螺杆菌一端有2-6根鞭毛，运动活泼的革兰氏阴性螺杆菌 主要生化鉴定依据：脲素酶、过氧化氢酶、氧化酶均为阳性

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