title: Allelic types of long polar fimbriae in bovine and human Escherichia coli O157 strains.
abstract: Long polar fimbriae (Lpf) are recently discovered adhesins and increasingly important genetic markers of pathogenic Escherichia coli strains. The presence and genotype diversity of Lpf operons was screened in a collection of 97 Escherichia coli O157 strains representing different pathotypes, isolated from healthy cattle (n = 43) and human patients (n = 54) in several countries. Individual structural genes of Lpf were scanned by PCR, and allelic variants were detected with a recently developed typing scheme. Ninety-five strains carried at least one whole Lpf operon (genes lpfABCD and/or lpfABCDE). The 64 enterohaemorrhagic (EHEC) and 24 enteropathogenic (EPEC) strains all carried two Lpf operons, allele 3 of lpfA1 and allele 2 of lpfA2, a combination characteristic of the O157:H7/NM serotype. Out of the 9 bovine atypical (AT; stx-, eae-) strains, 7 carried one complete Lpf operon, allele 1 of lpfA2. The atypical strains belonged to main phylogenetic groups A and B1, while the EHEC and EPEC strains were from group D. Lpf variants carried by the 72 strains of the Escherichia coli Reference Collection (ECOR) were determined with the same typing scheme. Alleles were detected in 25 strains, of which 6 were found negative for the respective Lpf operons in earlier studies. The marker value of the Lpf allelic combination for the O157:H7/NM serotype was confirmed, and further evidence was given for the presence of at least two different genetic lineages of atypical bovine E. coli O157 strains.
authors.affiliation: Hungarian Academy of Sciences Veterinary Medical Research Institute, Budapest, Hungary.
authors.forename: Domonkos
authors.initials: D
authors.lastname: Sváb
authors.forename: István
authors.initials: I
authors.lastname: Tóth
mesh_terms: D000483:Alleles; D000818:Animals; D002417:Cattle; D019453:Escherichia coli O157 / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D036781:Fimbriae Proteins / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D014644:Genetic Variation; D005838:Genotype; D006801:Humans
chemical_list: D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins