Post-weaning diarrhea caused by Escherichia coli: Prevalence, antibiotic resistance, investigation of risk factors and control methods

Post-weaning E. coli diarrhea in pigs is associated with increased mortality and antimicrobial use. In a cross-sectional study of 70 farms in Ontario E. coli O149:K91:F4 was isolated from 30% of the herds. Multi-drug resistance was common with these isolates and it was associated with the use of antimicrobials on farms. Six isolates of lactic acid bacteria (LAB) of pig origin were chosen based on their ability to inhibit E. coli O149:K91:F4 and for their ability to grow in low pH 4 and bile 0.3%. It was observed that fermenting liquid whey+dextrose with lactic acid bacteria ensured a more reliable controlled fermentation. The effectiveness of using specific Lactobacilli of pig origin to inoculate fermented liquid feed to control E. coli diarrhea was tested by means of a controlled trial using experimental infection and in a field trial with natural infection. There was no benefit observed. It was concluded that probiotics may have some value in improving overall gut health, but there was no evidence from these experiments that this is a useful approach to prevent post-weaning E. coli diarrhea in pigs.