A recent study led by Dr. Tim Johnson, a professor in the Department of Veterinary and Biomedical Sciences at the University of Minnesota College of Veterinary Medicine, confirmed that a new approach to analyzing avian pathogenic Escherichia coli (APEC) can help scientists identify the most high-risk types of APEC. Ultimately, this will help producers identify these problematic strains earlier, and control their spread through vaccination and other procedures.
APEC can cause colibacillosis in poultry. Among the most rampant and economically devastating bacterial diseases found in poultry across the globe, colibacillosis results in millions of dollars lost for the U.S. poultry industry every year. The disease causes respiratory distress, reduced appetite, poor growth and even death. However, APEC's ability to infect a turkey or chicken varies—some strains are lower risk, and some are higher. Scientists have long seen that certain groups of APEC are more likely to make birds sick than others, and have been working to decipher what genetic traits make an APEC strain high-risk.
Their work builds on a previous study the team published in late 2022, which focused on redefining the classification of APEC. In the 2022 study, they used genomic analysis to better understand the genetic makeup of these strains and redefine how they are categorized as high-risk or low-risk. Their new approach, which focuses on a specific piece of genetic material called the "APEC plasmid" that is often linked to severe disease, offers researchers a helpful tool to identify the most problematic APEC strains, and to differentiate them from the immense populations of E. coli found in every bird.
The more recent study expanded on their new method for identifying the high-risk types of APEC by testing it across additional populations of E. coli from both chickens and turkeys. The researchers found that the APEC in sick turkeys differed from the APEC in sick broiler chickens by belonging to different genetic lineages. The scientists also saw that nearly all the APEC found in sick birds was high-risk, but only about half of the APEC found in healthy birds was high-risk.
A limitation to this work, Johnson says, is that there are thousands of different APEC strains circulating in poultry, and these populations are constantly evolving and changing. So, researchers will need to modify the approach to match the current landscape of APEC. However, the research team's approach builds the foundation of using high-throughput genomics for quickly identifying and making the necessary modifications.
"Poultry producers are struggling with bacterial disease like E. coli, especially in this new era where raising birds in antibiotic-free conditions is becoming a consumer demand," says Johnson. "Our genomics-based approach not only helps producers quickly identify and mitigate problematic APEC on the farm, it also paves the way for understanding and dealing with other emerging bacterial disease issues in poultry production."
Read the full study in Poultry Science.