New strategies to prevent and control avian pathogenic Escherichia coli (APEC)

Avian pathogenic Escherichia coli (APEC) infections are associated with major economical losses and decreased animal welfare. In broiler production, APEC infections have traditionally been controlled by antibiotics, resulting in an increased prevalence of antibiotic-resistant E. coli. Concerns have been raised that transfer of antibiotic-resistant APEC via the food chain may result in risks for extra-intestinal infection of humans related to zoonotic transfer and increased difficulties in the treatment of human infections caused APEC-related E. coli types. In this review, the risks associated with APEC are presented based on new knowledge on transmission, virulence and antibiotic resistance of APEC. A major new change in our understanding of APEC is the high degree of genuine vertical transfer of APEC from parents to offspring. A new strategy for controlling APEC, including control of antibiotic-resistant APEC, has to focus on limiting vertical transfer from parents to offspring, and subsequent horizontal transmission within and between flocks and farms, by using all-in-all-out production systems and implementing a high level of biosecurity. Vaccination and the use of competitive exclusion are important tools to be considered. A specific reduction of antibiotic-resistant APEC can be obtained by implementing culling strategies, only allowing the use of antibiotics in cases where animal welfare is threatened. Strategies to reduce APEC, including antibiotic-resistant APEC, need to be implemented in the whole production pyramid, but it has to start at the very top of the production pyramid.