title: Pathology and Molecular Characterization of Escherichia Coli Associated With the Avian Salpingitis-Peritonitis Disease Syndrome.
abstract: Outbreaks of salpingitis and peritonitis cause major economic losses due to high mortality, reduced egg-production, and culling. The aim of the present study was to characterize, in detail, lesions associated with increased mortality in layers due to avianpathogenic Escherichia coli (APEC) and to investigate the population structure of the E. coli involved, which is important for selection of optimal treatment and prophylactic strategies. Among 322 layers received from eight farms with increased mortality due to E. coli, three lesion types were observed; sepsis-like lesions, chronic salpingitis and peritonitis, and chronic salpingitis and peritonitis associated with sepsis-like lesions. One hundred isolates of E. coli obtained in pure culture from the different lesion types were selected for genetic characterization. Six out of 10 submissions (two farms with two submissions) were considered clonal as defined by more than 85% of the typed isolates of E. coli belonging to the same sequence-type (ST). B2 was the most-prevalent phylogroup, including the clonal complex of ST95. The most-important virulence genes of E. coli were demonstrated from both clonal and nonclonal outbreaks, and major differences as to phylogeny and virulence genes were not observed between the lesion types. Cannibalism was more-often observed during polyclonal outbreaks. A new pathotype of APEC is suggested based upon lesions and route of infection, high similarity of virulence genes including plasmid-associated genes, and high frequency of ST95 and other isolates belonging to phylogroup B2. Compared to the best-known pathotypes of E. coli, this needs further investigations, including infection experiments to show if single virulence factors can be pointed out that are specific for the salpingitis-peritonitis pathotype and possibly not found in other pathotypes of E. coli.
authors.affiliation: A University of Copenhagen, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, Stigbøjen 4, DK-1870 Frederiksberg C, Denmark.
authors.forename: Rikke
authors.initials: R
authors.lastname: Heidemann Olsen
authors.affiliation: B Horsevænget 40, DK-4130, Viby Sjaelland, Denmark.
authors.forename: Magne
authors.initials: M
authors.lastname: Bisgaard
authors.affiliation: A University of Copenhagen, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, Stigbøjen 4, DK-1870 Frederiksberg C, Denmark.
authors.forename: Jens Peter
authors.initials: JP
authors.lastname: Christensen
authors.affiliation: C Knowledge Centre for Agriculture, Agro Food Park 15, DK-8200 Aarhus N, Denmark.
authors.forename: Susanne
authors.initials: S
authors.lastname: Kabell
authors.affiliation: A University of Copenhagen, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, Stigbøjen 4, DK-1870 Frederiksberg C, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Christensen
mesh_terms: D000818:Animals; D002645:Chickens; D003718:Denmark / Q000453:epidemiology; D004926:Escherichia coli / Q000235:genetics* / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D005260:Female; D010538:Peritonitis / Q000453:epidemiology / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D011201:Poultry Diseases / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology; D015995:Prevalence; D012488:Salpingitis / Q000453:epidemiology / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D037521:Virulence Factors / Q000235:genetics
chemical_list: D037521:Virulence Factors
keywords: APEC; MLST; host susceptibility; pathology; virulence