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

禽大肠杆菌病是影响肉鸡的最常见细菌性疾病。为了更好地评估致病性大肠杆菌的多样性和起源品系感染鸟类，我们对80只肉鸡群进行了研究。在雏鸡到达农场之前，就在农场环境中（墙壁，进料器，进气口等）采集了样本，并且在交付时还对日龄雏鸡（DOC）和运输箱进行了采样。从这些样品以及表现出典型的大肠杆菌病症状的鸡的器官中获得分离物。使用高通量qPCR对分离株进行表征，以检测一系列遗传标记（植物群，主要血清群毒力标记等）。共研究了967株分离株，包括来自28例大肠杆菌病的203株，来自DOC的484株，来自运输箱的162株和来自农场环境的118株。这些分离株产生了416种不同的遗传特征，其中单个分离株中检测到267种，在来自9个农场的多达44个分离株中观察到了其他分离株。分离株跨系统群和主要血清群的分布随分离源而变化。从大肠埃希氏菌病病例获得的分离株具有单一的遗传特征或不同。在少数情况下，我们观察到从相同群或不同群的DOC和大肠杆菌病病损获得的分离株的特征相同。但是，一些接受了其他分离物污染的DOC的鸡群仍保持健康，这些分离物带有在其他鸡群中发现的大肠杆菌病病例的遗传特征。这项研究突出了鸟类致病性和非致病性的巨大多样性 从大肠埃希氏菌病病例获得的分离株具有单一的遗传特征或不同。在少数情况下，我们观察到从相同群或不同群的DOC和大肠杆菌病病损获得的分离株的特征相同。但是，一些接受了其他分离物污染的DOC的鸡群仍保持健康，这些分离物带有在其他鸡群中发现的大肠杆菌病病例的遗传特征。这项研究突出了鸟类致病性和非致病性的巨大多样性 从大肠埃希氏菌病病例获得的分离株具有单一的遗传特征或不同。在少数情况下，我们观察到从相同群或不同群的DOC和大肠杆菌病病损获得的分离株的特征相同。但是，一些接受了其他分离物污染的DOC的鸡群仍保持健康，这些分离物带有在其他鸡群中发现的大肠杆菌病病例的遗传特征。这项研究突出了鸟类致病性和非致病性的巨大多样性大肠杆菌菌株。