a novel opportunistic pathogen in poultry.

[H. Kurth, 1883. Ueber , eine neue Bakterienart. , 1, 97-100] was isolated on 10 unrelated laying hen farms over a period of 15 months. Farmers reported elevated morbidity and mortality rates, and suspected colibacillosis based on the necropsy findings. The most frequently found lesions were perihepatitis, fibrinous peritonitis, salpingitis and oophoritis. Necropsy findings and bacteriological results allowed the diagnosis of colibacillosis. In addition, was isolated from the ovarian follicles (44.44%), liver (22.22%), peritoneum (16.67%), bone marrow (5.56%), spleen (5.56%), and duodenum (5.56%). On all farms, coinfection with was detected, while on some farms other common avian pathogens were found as well. In total, 18 strains were identified and phylogenetically analysed based on the 16S rRNA gene sequences. The results showed some variability of the strains originating from the same farm, although the overall phylogenetic diversity was low, regardless of the geographical location of the farm, age of the flock or date of collection. Embryo lethality assay showed is not able to cause a primary infection. We conclude that may play a role as an opportunistic pathogen for poultry. This is the first report of coinfection of and in laying hens. RESEARCH HIGHLIGHTS is a novel opportunistic pathogen in poultry.Phylogenetic analysis showed low genetic diversity of isolates.Embryo lethality assay showed does not cause primary infections.