Identification of enterotoxigenic Escherichia coli isolated from swine with diarrhea in Thailand by colony hybridization, using three enterotoxin gene probes.

The DNA colony hybridization assay was used to identify enterotoxigenic Escherichia coli among E. coli isolated from 803 swine with diarrhea at 10 farms in Thailand. Between 5 September and 8 December 1981, enterotoxigenic E. coli were identified in 40% of 58 litters of piglets under 10 days old and 17% of 29 litters between 10 and 21 days old with diarrhea at farms at four different locations in Thailand. All E. coli that hybridized with one or more of the three enterotoxin gene probes produced heat-labile or heat-stable toxin or both, as determined by testing culture supernatants in the Y1 adrenal and suckling mouse assays. The DNA colony hybridization technique is a specific method of identifying enterotoxigenic E. coli from swine and can be used to further characterize these enteric pathogens.