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Journal of Clinical Microbiology, January 2003, p. 218-226, Vol. 41, No. 1
0095-1137/03/$08.00+0 DOI: 10.1128/JCM.41.1.218-226.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.
Laboratoire de Microbiologie, Centre de Recherche, INRA de Clermont-Ferrand-Theix, 63122 St Genès Champanelle,1 Unité de Pathogénie Bactérienne des Muqueuses, Institut Pasteur, 75724 Paris Cedex 15,2 Laboratoire de Bactériologie, Faculté de Médecine, 63001 Clermont-Ferrand Cedex, France3
Received 6 May 2002/ Returned for modification 18 June 2002/ Accepted 24 October 2002
The afimbrial AfaE-VIII adhesin is common among Escherichia coli isolates from calves with intestinal and/or extraintestinal infections and from humans with sepsis or pyelonephritis. The virulence genotypes of 77 Escherichia coli afa-8 isolates from farm animals and humans were compared to determine whether any trait of commonality exists between isolates of the different host species. Over half of the extraintestinal afa-8 isolates were associated with pap and f17Ac adhesin genes and contained virulence genes (pap, hly, and cnf1) which are characteristic of human extraintestinal pathogenic E. coli (ExPEC). PapG, which occurs as three known variants (variants I to III), is encoded by the corresponding three alleles of papG. Among the pap-positive strains, new papG variants (papGrs) that differed from the isolates with genes for the three adhesin classes predominated over isolates with papG allele III, which in turn were more prevalent than those with allele II. The data showed the substantial prevalence of the enteroaggregative E. coli heat-stable enterotoxin gene (east1) among afa-8 isolates. Most of the afa-8 isolates harbored the high-pathogenicity island (HPI) present in pathogenic Yersinia; however, two-thirds of the HPI-positive strains shared a truncated HPI integrase gene. The presence of ExPEC-associated virulence factors (VFs) in extraintestinal isolates that carry genes typical of enteric strains and that express O antigens associated with intestinal E. coli is consistent with transfer of VFs and O-antigen determinants between ExPEC and enteric strains. The similarities between animal and human ExPEC strains support the hypothesis of overlapping populations, with members of certain clones or clonal groups including animal and human strains. The presence of multiple-antibiotic-resistant bovine afa-8 strains among such clones may represent a potential public health risk.
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