Diversity of Escherichia coli strains isolated from day-old broiler chicks, their environment and colibacillosis lesions in 80 flocks in France

Avian colibacillosis is the most common bacterial disease affecting broilers. To better evaluate diversity and origin of causative Escherichia coli strains infecting birds, we conducted a study on 80 broiler flocks. Just before arrival chicks farm, samples were collected in farm environment (walls, feeders, air inlets, etc.) and, upon delivery, day-old (DOCs) transport boxes also sampled. Isolates obtained from these samples, organs chickens exhibiting typical symptoms. The isolates characterized using high-throughput qPCR to detect range genetic markers (phylogroups, main serogroups virulence markers, etc.). A total 967 studied, including 203 28 episodes, 484 DOCs, 162 118 environment. These yielded 416 different profiles, which 267 detected single isolates, others observed up 44 nine farms. distributions across phylogroups varied with isolation. cases either shared profile or different. In few cases, same for DOCs lesions flock However, some flocks receiving contaminated bearing identified other remained healthy. This highlights huge among avian E. isolated diseased non birds.