The role of Shigella spp., enteroinvasive Escherichia coli, and other enteropathogens as causes of childhood dysentery in Thailand

Shigella spp. were isolated from 44%, Pleisomonas shigelloides from 22%, Campylobacter spp. from 16%, and Salmonella spp. from 10% of 200 Thai children with mucoid or bloody diarrhea. Enteroinvasive Escherichia coli (EIEC) was identified by examining isolates of E. coli for plasmids larger than 120 megadaltons (MDa), by identifying E. coli with a virulence marker antigen in an ELISA, and by performing DNA hybridization with a 17-kilobase (kb) EcoRI digestion fragment of plasmid pWR100 (a 140-MDa plasmid of Shigella flexneri 5). Sixty-four isolates of EIEC from 10 (5%) of the children were identified by these methods and confirmed by the Sereny test. All isolates of EIEC fermented lactose, and isolates of EIEC from seven children belonged to recognized serotypes of EIEC (O28ac:H- and O29:H-), whereas isolates of EIEC from three children were untypable. Examination of DNA from the total fecal growth with the 17-kb probe identified 9 of 10 children from whom EIEC were isolated and 2 of 102 children from whom EIEC or Shigella spp. were not isolated. Detection of EIEC by ELISA and DNA hybridization are important advances in defining the etiology of dysentery.