Common virulence factors and genetic relationships between O18 : K1 : H7 Escherichia coli isolates of human and avian origin

in Journal of Clinical Microbiology (2006), 44(10), 3484-3492

Extraintestinal pathogenic (ExPEC) Escherichia coli strains of serotype 018:K1:H7 are mainly responsible for neonatal meningitis and sepsis in humans and belong to a limited number of closely related ... [more ▼]

Extraintestinal pathogenic (ExPEC) Escherichia coli strains of serotype 018:K1:H7 are mainly responsible for neonatal meningitis and sepsis in humans and belong to a limited number of closely related clones. The same serotype is also frequently isolated from the extraintestinal lesions of colibacillosis in poultry, but it is not well known to what extent human and avian strains of this particular serotype are related. Twenty-two ExPEC isolates of human origin and 33 isolates of avian origin were compared on the basis of their virulence determinants, lethality for chicks, pulsed-field gel electrophoresis (PFGE) patterns, and classification in the main phylogenetic groups. Both avian and human isolates were lethal for chicks and harbored similar virulence genotypes. A major virulence pattern, identified in 75% of the isolates, was characterized by the presence of F1 variant fimbriae; S fimbriae; IbeA; the aerobactin system; and genomic fragments A9, A12, D1, D7, D10, and D11 and by the absence of P fimbriae, F1C fimbriae, Afa adhesin, and CNF1. All but one of the avian and human isolates also belonged to major phylogenetic group B2. However, various subclonal populations could be distinguished by PFGE in relation to animal species and geographical origin. These results demonstrate that very closely related clones can be recovered from extraintestinal infections in humans and chickens and suggest that avian pathogenic E. coli isolates of serotype 018:K1:H7 are potential human pathogens. [less ▲]

Examination of Escherichia coli from poultry for selected adhesin genes important in disease caused by mammalian pathogenic E-coli

in Veterinary Microbiology (2002), 84(3), 231-241

A collection of 1601 extraintestinal and intestinal Escherichia coli isolated from chickens, turkeys and ducks. in Belgium, France and Spain, was hybridised with gene probes specific for fimbrial and ... [more ▼]

A collection of 1601 extraintestinal and intestinal Escherichia coli isolated from chickens, turkeys and ducks. in Belgium, France and Spain, was hybridised with gene probes specific for fimbrial and afimbrial adhesins (F17, F18, S (Sfa/F1C), Bfp, Afa, Cs31A, Intimin (Eae), Aida-1) of intestinal, urinary and invasive E. coli of mammals and with a probe specific for the P (Pap/Prs) fimbrial adhesin of urinary and invasive E. coli of mammals and birds. Three hundred and eighty-three strains (23.9%) were P-positive, 76 strains (4.8%) were Afa-positive, 75 strains (4.7%) were F17-positive, 67 strains (4.2%) were S-positive, 23 (1.4%) were Intimin-positive. and all were F18-, Cs31A-, Aidal- and Bfp-negative. The 75 F17-positive strains harboured different major subunit A-encoding gene variants, but the f17Ac variant was the most frequent (52 strains, 69,3%) and seven strains (9.3%) were not typeable. The f17G gene variant coding for the GII adhesin was the most frequent (56 strains, 75.0%), whereas the f17GI gene variant was present in four strains (5%) and 15 strains (20.0%) were not typeable. All Afa-positive strains harboured the afa-8 variant. The 23 Intimin-positive E. coli tested positive for the beta -variant (16 strains; 69.6%) or for the gamma -variant (seven strains;, 30.4%) of the eae gene. Chicken and turkey E. coli were more frequently probe-positive (43.6 and 43.1 %, respectively) than duck E. coli 31.5%) and extraintestinal E. coli were also more frequently probe-positive (48.4%) than intestinal strains (18.5%). Different combinations of probe positive hybridisation results were observed in 72 of the 540 probe-positive E. coli (13.3%). The most frequent combinations were between AfaE-8 and F17 probes (47 strains; 8.7%) and between P and S probes (13 strains. 2.4%). Although f17- and afa-8-related DNA sequences can be plasmid-located in mammalian E. coli. they were not in avian E. coli. Besides the P fimbrial adhesin, F17 and S fimbrial and Afa-VIII and Intimin afimbrial adhesins may thus represent colonisation factors of avian pathogenic E. coli. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]