医学微生物学英文版教学课件：第9章 Enterobacteriaceae

1、Enterobacteriaceae I.Common properties:1. Similar shape: G- rods, most possess flagella and pili. No spores, certain members possessing capsules.2. Culture: aerobe or facultative, 2-3mm colonies Enterobacteriaceae 3. Biochemical reactions: Biochemical reactions active and diverse. Differentiation: L

2、actose fermenting bacteria enteric non-pathogens Non-lactose fermenting bacteria enteric pathogens Enteric Bacilli4. Antigenic structure: Antigenic structures are complex(1) O antigen - specific polysaccharides of LPS: Enteric Bacilli4.抗原结构 菌体O抗原、鞭毛H抗原、荚膜抗原 (2) Capsule Ag: Polysaccharides that cover

3、 the O Ags (e.g. capsule Ag) Main surface Ags: Vi antigen (S. typhi), K antigen (E. coli) (3) H Ag flagella protein: Enteric Bacilli 5. Resistance: Killed by heating at 60C for 30 min.Enteric Bacilli 6. Mutation Drug resistant Virulent Enteric BacilliEscherichia coliSection I. I. Biological characte

4、ristics Escherichia coliShape and structure: G- rods, possess flagella and pili.2. Culture: Common agar-18 hour,smooth colonies 23mm, colorless. Blood agar-hemolysis Escherichia coli3.Biochemical reactions : extremely active and complex 4. Antigenic structure: O Ag- more than 170 H Ag - more than 56

5、 specific K Ag - more than 100 e.g. serotype is expressed as O111:K58 :H2 Escherichia coli II.Pathogenicity Escherichia coli1.Pathogenic factors:(1)Invasiveness: adhesin: CFA (colonization factor Ag) pili: bondle forming pili, P pili, etc capsule: antiphagocytosis, adherence(2)Endotoxin: cell wall l

6、ipopolysaccharide ; fever / shockEscherichia coli(3) exotoxin * Hemolysin A (Hly A) * Enterotoxin, heat labile enterotoxin (LT) andheat stable enterotoxin (ST) * Stx-I, Stx-II Escherichia coli2. Infection (1).Outer-intestinal infections -caused by opportunistic pathogens * septicemia * neonatal meni

7、ngitis (new born) * urinary tract infection (uropathogenic E. coli, UPEC )Escherichia coliEscherichia coli (2).Diarrheal diseases -certain serotypes of E.coli Enterotoxigenic E.coli (ETEC) LT and/orST; Diarrhea; children(under 5 years),adult(travellers) Escherichia coliMechanism Heat labile toxinlik

8、e choleragenAdenyl cyclase activated cyclic AMP secretion water/ions Heat stable toxinGuanylate cyclase activated cyclic GMP uptake water/ions Escherichia coliMechenism of LT22 Enteroinvasive E.coli (EIEC) No exterotoxin; endotoxin; Diarrhea, like dysentery; Large intestine, Children, adults Enteroh

9、emorrhagic E. Coli (EHEC) O157:H7 Vero toxin, hemorrhagic colitis; HUSEscherichia coli24侵袭过程：Escherichia coli III. Laboratory diagnosis Escherichia coli 1.Specimen: feces, blood, pus, 2.Isolation and identification: * Biochemical reactions * serologic identificationEscherichia coli Escherichia coliE

10、lectron microscopelight microscopeEnterohemorrhagic E. coli O157:H7Electron microscope Biochemical Reaction Escherichia coliSection II ShigellaShigella I. Biological characteristics 1. G-, non-motile, possesses piliShigella2.Classification: 4 groups, 43 serotypes StrainGroupSerotypeMannitolS. dysent

11、eriaeA10-S. flexneriB8+S. boydiiC14+S. sonneiD1+Shigella II. pathogenicity and immunityShigella1. Pathogenic factor: Invassiveness: (1) Pili adhere ileum end epithelial cell(2) III type secret systemToxin(2) Endotoxin (3).Exotoxin: shiga toxin Stx-I, Stx-IIShigella2.disease: Acute dysentery chronic

12、dysentery Acute toxic dysenteryShigellaSection II SalmonellaHuman source (S. Typhi, S.paratyphi B, Salmonella hirschfeldii)zoonosis (S. choleraesuis, S. typhimurium etc.)Salmonella I. Biological characteristics 1.Morphology and biochemical reactions: (1)Morphology: G-, peritrichous; (2)Culture: grow

13、 in simple cultural media, SalmonellaSalmonellaSalmonellaII. Pathogenicity and immunity1.Pathogenic factors(1).Invasiveness (intracelllular bacteria ) III secret system Vi antigen -antiphagocytosis(2).Endotoxin(3).Enterotoxin S. typhimurium: LT/ST SalmonellaSalmonella2.Pathogenesis(1).Septicemia: Pn

14、eumonia; osteomyelitis; meningitis(2).Enterocolitis (Food poisoning) World wide; incubation period: 624hour(3).Enteric fever: Organism typhoid (caused by S. typhi) paratyphoid (caused by S. Paratyphi A,B,C) 胆囊-肝-肾-脾-骨髓-致病过程细菌肠系膜淋巴结大量繁殖 伊派尔淋巴结M细胞 巨噬细胞吞噬 进入血液再次进入血液第一次菌血症第二次菌血症（发热、不适、全身疼痛等） （持续高热、相对缓脉、

15、 肝脾肿大、玫瑰疹等） 粪便排菌；坏死、溃疡，出血或肠穿孔尿液排菌 消化道(粪口途径) (4) asymptomatic carriers Salmonella IV. Laboratory diagnosis 1.Bacteriological methods 1) Specimen 2). Identification. Salmonella2.Serological methods (Widal test)(1)To detect the unknown Ab with given Ag(O, H, HA, HB, Hc) tube agglutination.SalmonellaSalmon