Traveller's diarrhoea is most commonly caused by

Ans. a (ETEC). (Ref. Harrison, 18th/Table 149-2; Chapter 149. Diseases by Gram-Negative Enteric Bacilli)Five types of E.coli include:1. ETEC (enterotoxogenic E.coli)2. EIEC (enteroinvasive E.coli)3. EPEC (enteropathogenic E.coli)4. EHEC (enterohemorrhagic E.coli)5. EAEC (enteroaggregative E.coli)Traveller's 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 ElementSTEC/EHECFood, 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 countriesTraveller's diarrheaHeat-stable and - labile enterotoxins, colonization factorsVirulence plasmid(s)EPECPerson-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 effacement)EIECFood, 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 countriesTraveller's, acute, Persistent diarrheaAggregative/diffuse 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