ENTEROTOXIGENIC E.COLI

key pathogenic mechanism / virulence factor

1. colonization factor antigen (CFA/I , II, III)

2. heat labile toxin (LT)

3. heat stable toxin (ST)

• palsmid mediated—transmissible plasmid

• ETEC strain can produce either LT or ST or both

clinical manifesttaion and complication

1. self limited

2. watery diarrhea

3. dvlpd 1-3 days later

4. symptom similar to cholera but milder

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causing:

1. Traveler’s diarrhea

2. Weanling diarrhea (Infant diarrhea)

mode of transmission

1. fecal oral

2. no person to person spread

pathogenesis

STEP 1 : COLONIZATION FACTOR

• attachement on host intestinal

STEP 2 : elaborate plasmid encoded enterotoxin

• Heat stable toxin

• Heat labile toxin

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PATHOGENESIS OF HEAT LABILE TOXIN

1. B subunit of LT toxin bind to GM1 ganglioside of host epithelium

2. endocytosis into epithelium

3. A subunit moves across the membrane vacuole

4. interact with membrane protein , regulate adenylate cyclase

5. increase cAMP level

6. decrease absorption of Cl- and Na+ , increase secretion of Na+

7. manifest water diarrhea

8. activate secretio of PG and production of inflammatory cytokine

9. further fluid loss

compare LT and ST toxin

diagnosis of ETEC

1. samples

• patients and food sample

2. molecular method

• PCR genotyping → identify gene encode LT and ST toxin

• DNA probe → detect virulence gene in stool

3. immunoassay (ELISA )

• detect LT and ST enterotoxin in stool

treatment

1. supportive measure : fluid balance

2. no hospitalization/ antibiotic