<prompt> Travellers diarrhoea is most commonly caused byETECS. dysenteriaeEPECSalmonella  <response>: Ans. a ETEC. Ref. Harrison, 18thTable 149-2; Chapter 149. Diseases by Gram-Negative Enteric BacilliFive types of E.coli include:1. ETEC enterotoxogenic E.coli2. EIEC enteroinvasive E.coli3. EPEC enteropathogenic E.coli4. EHEC enterohemorrhagic E.coli5. EAEC enteroaggregative E.coliTravellers diarrhoea is most commonly caused by enterotoxogenic E.coli and then the other common organism responsible is S. dysenteriae.Intestinal Pathogenic E. ColiPathotypeEpidemiologyClinical SyndromeDefining Molecular TraitResponsible Genetic ElementSTECEHECFood, water, person-to- person; all ages, industrialized countriesHemorrhagic colitis, HUSShiga toxinLambda-like Stxl- or Stx2- encoding bacteriophageETECFood, water; young children and in travellers to developing countriesTravellers diarrheaHeat-stable and - labile enterotoxins, colonization factorsVirulence plasmidsEPECPerson-to-person; young children and neonates in developing countriesWatery diarrhea, persistent diarrheaLocalized adherence, attaching and effacing lesion on intestinal epitheliumEPEC adherence factor plasmid pathogenicity island locus for enterocyte effacementEIECFood, water; children and in travellers to developing countries.DysenteryColonic epithelial cell invasion intra- cellular multipli cation, cell-to-cell spread.Multiple genes contained primarily in a large virulence plasmidEAEC?Food, water; children and in travellers to developing countries; all ages, industrialized countriesTravellers, acute, Persistent diarrheaAggregativediffuse adherence, virulence factors regulated by AggRChromosomal or plasmid associated adherence and toxin genesE.coli toxin GSa, cholera toxin Gsa, Pertusis toxin Gla cause ADP-ribosylation 