phaidra.vetmeduni.ac.at o:2983 DOI 10.1038/s41598-024-58706-3 A comprehensive study of colisepticaemia progression in layer chickens applying novel tools elucidates pathogenesis and transmission of Escherichia coli into eggs Colisepticaemia caused by avian pathogenic Escherichia coli (APEC) is a challenging disease due to its high economic importance in poultry, dubious pathogenesis and potential link with zoonosis and food safety. The existing in vitro studies can't define hallmark traits of APEC isolates, suggesting a paradigm shift towards host response to understand pathogenesis. This study investigated the comprehensive pathological and microbial progression of colisepticaemia, and transmission of E. coli into eggs using novel tools. In total 48 hens were allocated into three groups and were inoculated intratracheally with ilux2-E. coli PA14/17480/5-/ovary (bioluminescent strain), E. coli PA14/17480/5-/ovary or phosphate buffered saline. Infection with both strains led to typical clinical signs and lesions of colibacillosis as in field outbreaks. Based on lung histopathology, colisepticaemia progression was divided into four disease stages as: stage I (1-3 days post infection (dpi)), stage II (6 dpi), stage III (9 dpi) and stage IV (16 dpi) that were histologically characterized by predominance of heterophils, mixed cells, pyogranuloma, and convalescence, respectively. As disease progressed, bacterial colonization in host organs also decreased, revealed by the quantification of bacterial bioluminescence, bacteriology, and quantitative immunohistochemistry. Furthermore, immunofluorescence, immunohistochemistry, and bacteria re-isolation showed that E. coli colonized the reproductive tract of infected hens and reached to egg yolk and albumen. In conclusion, the study provides novel insights into the pathogenesis of colisepticemia by characterizing microbial and pathological changes at different disease stages, and of the bacteria transmission to table eggs, which have serious consequences on poultry health and food safety. eng Animals; Female; Escherichia coli; Chickensmicrobiology; Poultry Diseasesmicrobiology; Escherichia coli Infectionsmicrobiology; Egg Yolk 2024-05-15T08:35:11.681Z LOMv1.0 Author BEGIN:VCARD VERSION:3.0 N:Abdelhamid;Mohamed Kamal; FN:Mohamed Kamal Abdelhamid X-ORCID:https://orcid.org/0000-0002-8136-9170 END:VCARD BEGIN:VCARD VERSION:3.0 N:Paudel;Surya; FN:Surya Paudel X-ORCID:https://orcid.org/0000-0002-4527-9733 END:VCARD BEGIN:VCARD VERSION:3.0 N:Hess;Michael; FN:Michael Hess X-ORCID:https://orcid.org/0000-0002-6991-0120 END:VCARD BEGIN:VCARD VERSION:3.0 N:Liebhart;Dieter; FN:Dieter Liebhart X-ORCID:https://orcid.org/0000-0003-2412-1248 END:VCARD BEGIN:VCARD VERSION:3.0 N:Rehman;Hammad Ur; FN:Hammad Ur Rehman END:VCARD BEGIN:VCARD VERSION:3.0 N:Glösmann;Martin; FN:Martin Glösmann X-ORCID:https://orcid.org/0000-0002-2094-3247 END:VCARD BEGIN:VCARD VERSION:3.0 N:Hess;Claudia; FN:Claudia Hess X-ORCID:https://orcid.org/0000-0002-3535-5157 END:VCARD BEGIN:VCARD VERSION:3.0 N:Bilic;Ivana; FN:Ivana Bilic X-ORCID:https://orcid.org/0000-0003-3296-5117 END:VCARD https://w3id.org/kim/hcrt/scheme https://w3id.org/kim/hcrt/text Textdokument Text LOMv1.0 yes https://creativecommons.org/licenses/by/4.0 application/pdf 4345360 https://phaidra.vetmeduni.ac.at/o:2983 https://phaidra.vetmeduni.ac.at/api/object/o:2983/thumbnail LOMv1.0 discipline