ENTEROAGGREGATIVE E.COLI

key pathogenic mechanism

1. Aggregative adherence fimbriae (AAF/ I , II, III)

2. enteroaggregative heat stable toxin; plasmid encoded toxin

clinical manifestation and complication

1. childhood diarrhea in developing countries

2. chronic diarrhea and growth retardation in children

3. emergic enteric diarrhea

4. watery diarrhea

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   Autoagglutination (AA) into a stacked brick arrangement on small instestine and colon epithelium
   

pathogenesis

STAGE 1

• colonization/ aggregation of mucosa facilitated by AAF/I and AAF/II

STAGE 2

• inc mucus production - formation of thick biofilm on mucosa- encrusted of mucosa with EAEC

• promote persistent colonization and nutrient malabsorption

STAGE 3

• elaboration of toxins

- EAEC cytotoxin→ damaged intestine

- EAST 1 toxin

- cytokine release → inc neutrophil recruitment → inflammatory diarrhea

• lead to shortening of villi

• mononuclear infiltration

• hemorrhage

• dec fluid absorption

• malnourished host : unable to repair damage lead to persistent diarrhea

diagnosis

1. culture

• isolation of E.coli from stool

2. identificationb of EAEC

• HEp2 assay→ gold standard

• DNA probe → PCR assay using AA probe

3. additional test

• Pellicle form in Mueller Hinton Agar

• biofilm formation in polystyrene culture tubes or dishes incubated at 37C overnight

treatment

• self limited

• rehydration

• antibiotic for chronic / persistent cases