title: Diagnostic strategy for identifying avian pathogenic Escherichia coli based on four patterns of virulence genes.
abstract: In order to improve the identification of avian pathogenic Escherichia coli (APEC) strains, an extensive characterization of 1,491 E. coli isolates was conducted, based on serotyping, virulence genotyping, and experimental pathogenicity for chickens. The isolates originated from lesions of avian colibacillosis (n = 1,307) or from the intestines of healthy animals (n = 184) from France, Spain, and Belgium. A subset (460 isolates) of this collection was defined according to their virulence for chicks. Six serogroups (O1, O2, O5, O8, O18, and O78) accounted for 56.5% of the APEC isolates and 22.5% of the nonpathogenic isolates. Thirteen virulence genes were more frequently present in APEC isolates than in nonpathogenic isolates but, individually, none of them could allow the identification of an isolate as an APEC strain. In order to take into account the diversity of APEC strains, a statistical analysis based on a tree-modeling method was therefore conducted on the sample of 460 pathogenic and nonpathogenic isolates. This resulted in the identification of four different associations of virulence genes that enables the identification of 70.2% of the pathogenic strains. Pathogenic strains were identified with an error margin of 4.3%. The reliability of the link between these four virulence patterns and pathogenicity for chickens was validated on a sample of 395 E. coli isolates from the collection. The genotyping method described here allowed the identification of more APEC isolates with greater reliability than the classical serotyping methods currently used in veterinary laboratories.
authors.affiliation: INRA, UR1282 Infectiologie Animale et Santé Publique, Nouzilly, France. catherine.schouler@tours.inra.fr
authors.forename: Catherine
authors.initials: C
authors.lastname: Schouler
authors.forename: Brigitte
authors.initials: B
authors.lastname: Schaeffer
authors.forename: Annie
authors.initials: A
authors.lastname: Brée
authors.forename: Azucena
authors.initials: A
authors.lastname: Mora
authors.forename: Ghizlane
authors.initials: G
authors.lastname: Dahbi
authors.forename: François
authors.initials: F
authors.lastname: Biet
authors.forename: Eric
authors.initials: E
authors.lastname: Oswald
authors.forename: Jacques
authors.initials: J
authors.lastname: Mainil
authors.forename: Jorge
authors.initials: J
authors.lastname: Blanco
authors.forename: Maryvonne
authors.initials: M
authors.lastname: Moulin-Schouleur
mesh_terms: D000818:Animals; D001530:Belgium; D002645:Chickens; D004372:Ducks; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000662:veterinary* / Q000821:virology; D029968:Escherichia coli Proteins / Q000235:genetics*; D005602:France; D005838:Genotype; D058889:Molecular Typing; D011201:Poultry Diseases / Q000382:microbiology*; D012703:Serotyping; D013030:Spain; D014422:Turkeys; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D029968:Escherichia coli Proteins; D037521:Virulence Factors