title: Clonal diversity among strains of Escherichia coli incriminated in turkey colisepticemia.
abstract: The extent of genetic differentiation among 80 Escherichia coli isolates collected from turkeys with acute colisepticemia was assessed based on allelic variation at 20 enzyme-encoding loci detected by multilocus enzyme electrophoresis. Isolates were polymorphic at 17 loci and were classified into 32 multilocus genotypes, delineating clones, that differed on average at 36% of the loci. In the total sample, 29 (36%) of the isolates belonged to one of two closely related clones, differing only in a single electromorph, and 11 of these isolates were serogroup O78. Most isolates fell into one of 4 genetically distinct clusters of strains. Three of these clusters represent E. coli clone complexes that have been previously identified in avian diseases and a fourth cluster which is specific to colisepticemia in turkeys. Most (73%) isolates produced aerobactin, whereas none produced hemolysins. Assays for detecting K1 capsules, including the use of polyclonal antisera, monoclonal antibodies, and K1-specific bacteriophages, gave variable results, but showed that overall 18% of the strains from colisepticemia were K1 encapsulated with most of the K1+ isolates found in one clone cluster. The results show that many cases of colisepticemia in turkey flocks are caused by a small number of pathogenic clones representing at least three distinct clone complexes.
authors.affiliation: Institute of Molecular Evolutionary Genetics, Pennsylvania State University, University Park 16802.
authors.forename: D G
authors.initials: DG
authors.lastname: White
authors.forename: R A
authors.initials: RA
authors.lastname: Wilson
authors.forename: D A
authors.initials: DA
authors.lastname: Emery
authors.forename: K V
authors.initials: KV
authors.lastname: Nagaraja
authors.forename: T S
authors.initials: TS
authors.lastname: Whittam
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis; D016470:Bacteremia / Q000382:microbiology / Q000662:veterinary*; D016667:Bacterial Capsules / Q000276:immunology; D004926:Escherichia coli / Q000737:chemistry / Q000201:enzymology / Q000235:genetics*; D004927:Escherichia coli Infections / Q000235:genetics / Q000662:veterinary*; D008040:Genetic Linkage; D014644:Genetic Variation; D006877:Hydroxamic Acids / Q000032:analysis; D011110:Polymorphism, Genetic; D011201:Poultry Diseases / Q000382:microbiology*; D012703:Serotyping; D014422:Turkeys
chemical_list: D000942:Antigens, Bacterial; D006877:Hydroxamic Acids; C031819:aerobactin