ESCHERICHIA COLI I

explain the terms diarrhea

passage of liquid or watery stool more than 3x a day due to infection, food intolerance and medication

explain the term dysentery

inflammation of lower GIT especially colon that causing diarrhea with mucus and blood

• due top Shigella spp. and Enteroameoba histolytica

compare food poisoining and food borne infection

describe general properties of E.coli

• motile , peritrichous

• Gram negative bacilli

• facucltative anaerobe

• possess type 1 fimbriae

• antigenic type

→ O (somatic)

→ F(fimbriae)
→ H (flagella)

→ K (capsule)

explain virulence factor of E.coli

1. fimbriae

• adhere to intestinal epithelium

• mannose-resistant agglutination

2. capsule

• antiphagocytosis

3. heat labile toxin

• watery diarrhea due to hypersecretion of fluid into lumen of gut

3. heat stable toxin

• increased secretion of fluid

5. shiga toxin

• cytotoxin

explain identification of E.coli

cultural characteristic

1. blood agar

2. MacConkey agar → lactose fermenter, pink colonies

3. Cysteine Lactose Electrolyte Deficiency → yellow colonies

---

biochemical test

• nitrate to nitrite

• catalase +ve

• oxidase -ve

• indole +

• citrate -

• urease -

• TSI +/+ gas+ no H2S