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

• Published in: Veterinary microbiology Vol. 252; p. 108923
• Main Authors: Delannoy, Sabine, Schouler, Catherine, Souillard, Rozenn, Yousfi, Léna, Le Devendec, Laetitia, Lucas, Camille, Bougeard, Stéphanie, Keita, Alassane, Fach, Patrick, Galliot, Pascal, Balaine, Loïc, Puterflam, Julie, Kempf, Isabelle
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.01.2021; Elsevier BV; Elsevier
• Subjects: Bacteriology; Broilers; Colibacillosis; Diversity; E coli; Escherichia coli; Farms; Genetic markers; Juveniles; Life Sciences; Microbiology and Parasitology; Strain; Strains (organisms); Virulence; Broilers; Colibacillosis; Diversity; Strain; strain; broilers; diversity; colibacillosis
• ISSN: 0378-1135; 1873-2542
• DOI: 10.1016/j.vetmic.2020.108923

•High-throughput qPCR was used to study 967 E. coli isolates from 80 broiler farms.•The 967 E. coli isolates yielded 416 different genetic profiles.•267 genetic profiles were singletons; one was detected in 44 isolates from nine farms.•The same profile could be obtained from day-old chicks and colibacillosis lesions.•The serogroup distribution of isolates varied with the origin of isolation. 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 among avian E. coli isolated from diseased and non diseased birds.