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.