Oral immunization against enterotoxigenic colibacillosis in weaned piglets by non-pathogenic Escherichia coli strain with K88 (F4) colonizing factors

Experiments were focused on the prevention of diarrhoea in weaned piglets by means of enterotoxigenic strains of Escherichia coli (ETEC) with colonizing factors K88 (F4). The process of immunization consisted of intramuscular administration of ETEC strain bacterin one day prior to weaning and oral administration of a live culture of non-pathogenic E. coli strain containing colonizing factors (O149:K88; STa–, LT–) in 3 hours after weaning. The shedding of the K88 positive E. coli strains was monitored for 3 weeks after weaning by the culture of rectal swabs. The efficacy of such immunization protocol was tested by challenge exposure to enterotoxigenic E. coli O149:K88, LT+ strain on the third or the tenth day after weaning. Following the oral administration of non-pathogenic E. coli strain containing colonizing factors K88 to piglets, the shedding of the administered strain continued for 9 days. No or very small protection against diarrhoea following the challenge exposure to enterotoxigenic E. coli was found in immunized piglets.