Impact of commercial vaccination on the ecology of avian pathogenic Escherichia coli in turkey production

Abstract

Escherichia coli is a bacteria ubiquitous to the healthy intestinal microflora in animals. Some E. coli can cause disease in poultry, but disease manifestation is a result of the balance between stress level in the bird and the virulence potential of E. coli strains present. The collection of diseases caused by E. coli is referred to as colibacillosis, and this disease has continually burdened the poultry industry through significant morbidity, mortality, condemnations, and reduced performance. Avian pathogenic E. coli (APEC) refers to strains with shared genetic traits enhancing their ability to cause colibacillosis and have been well characterized. However, less is known about the overall ecology of E. coli in poultry production and how ecology changes following mitigation strategies such as vaccination. We examined E. coli collected from a field trial following 8 barns comparing control versus commercially vaccinated barns within a single commercial turkey company and comparing matched brood versus growout barns. Our results revealed no significant differences in APEC status or proportions of high-risk clones in response to vaccination. APEC prevalence was significantly higher during the growout versus brood period. Phylogroups A, B1, C, D, E, F, and G showed subtle, but non-significant shifts between the control and vaccinated groups. However, significant shifts between the brood and growout periods were seen in phylogroups A, B1, and C. These findings suggest that application of a live attenuated vaccine has limited effects on the ecology of E. coli and APEC prevalence in healthy birds.