E. coli bacteria are typically harmless, but certain strains, known as Avian Pathogenic E. coli (APEC), can cause serious illness in poultry, leading to significant financial losses and animal welfare issues. New research from the University of Surrey and University of Bristol, in collaboration with Poultry Health Services, has determined why various strains of APEC behave so differently.

The study, published in Virulence analysed a colibacillosis outbreak in turkeys in the UK, and found that a strain called ST-101 was the dominant cause of the outbreak, accounting for nearly 60% of cases. This strain of APEC had not been previously reported as the primary cause of a turkey outbreak in the UK.

By comparing ST-101 to a variety of high-risk APEC strains, the team from Surrey, led by Dr Jai Mehat, Dr James Adams, and Professor Roberto La Ragione, found that the ST-101, ST-95 and ST-140 strains were found to be better at invading and surviving inside chicken gut cells and immune cells (macrophages) compared to the ST-23 and ST-117 strains. However, despite being less effective at invading cells, the ST-117 strain was found to be the most lethal in an insect model of infection, suggesting that different strains cause disease differently.

Dr Jai Mehat, senior author of the study and Lecturer in Molecular Bacteriology at the University of Surrey, said:

“Our research shows that a one-size-fits-all approach to controlling Avian Pathogenic E. coli (APEC) infections is not effective. Current vaccination strategies often target specific strains, but they may not protect against emerging APEC threats. Therefore, we need to develop new vaccines that can target a variety of APEC strains.”

Professor Shahriar Behboudi, co-author and Professor in Correlates of Immune Protection at the University of Bristol, said:

“We extrapolate that broad-spectrum control measures, including the induction of trained immunity in chickens to control diverse strains, offer more effective protection, as current vaccines typically target specific strains and may fail against emerging APEC threats.”

Dr Sara Perez, co-author and Clinical Director at Poultry Health Services, said:

“Infections caused by APEC are a foremost threat to farmed poultry. Increasing our surveillance of poultry flocks to better understand the presence and evolution of APEC strains, will ensure our animals’ welfare, and as a result, the safety of our food.”

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