title: The role of fimbriae and flagella in the colonization, invasion and persistence of Escherichia coli O78:K80 in the day-old-chick model.
abstract: To understand the role of flagella and fimbriae of Escherichia coli O78:K80 in avian colibacillosis, day-old chicks were dosed orally with defined afimbriate and or aflagellate mutants and colonization, invasion and persistence compared with that of the wild-type. In an invasion model, chicks were dosed with 1 x 10(5) c.f.u. of a single strain and mutants defective for type 1 fimbriae, curli fimbriae or flagella colonized livers by 24 h although the numbers of bacteria present were significantly less than the wild-type. Mutants colonized between 50 and 75% of spleens whereas the wild-type colonized 100% of spleens. Additionally, the numbers of mutant bacteria in colonized spleens were significantly less than the wild-type. Surprisingly, mutants defective for the elaboration of more than one appendage were no more attenuated than single mutants. In a persistence model, chicks were dosed with 1 x 10(2) c.f.u. of a single strain and mutants defective for type 1 or curli or flagella or any combination thereof persisted as assessed by cloacal swabbing for 5 weeks of the experiment less well than the wild-type. In an additional persistence model, chicks were dosed with 5 x 10(2) c.f.u. of each of wild-type and one mutant together. All mutants were significantly less persistent than the wild-type (P < 0.001) and one mutant which lacked type 1, curli and flagella, was eliminated within 2 weeks. Analysis of the trends of elimination indicated that flagella contributed to persistence more than curli, which contributed more than type 1 fimbriae. Here was evidence for a major role in colonization, invasion and persistence played by type 1, curli and flagella.
authors.affiliation: Bacteriology Department, Veterinary Laboratories Agency, Addlestone, Surrey, UK.
authors.forename: R M
authors.initials: RM
authors.lastname: La Ragione
authors.forename: A R
authors.initials: AR
authors.lastname: Sayers
authors.forename: M J
authors.initials: MJ
authors.lastname: Woodward
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D002645:Chickens; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D004927:Escherichia coli Infections / Q000382:microbiology* / Q000473:pathology; D010861:Fimbriae, Bacterial / Q000502:physiology*; D005407:Flagella / Q000502:physiology*; D009154:Mutation; D014774:Virulence