title: Duplex real-time PCR assays for rapid detection of virulence genes in E. coli isolated from post-weaning pigs and calves with diarrhoea.
abstract: Duplex real-time PCR assays were used as modules to cover partially automated detection of 12 genes encoding adhesins, enterotoxins and Shiga toxins in faecal E. coli isolates. For this a total of 194 E. coli isolates from pigs suffering from post-weaning diarrhoea (PWD), including 65 isolates with haemolytic activity, and 83 isolates from calves with diarrhoea were examined. Data obtained by PCR were compared with O-typing and with haemolytic activity as indirect virulence markers. E. coli O-types O139:K82, O141:K85, and O149:K91 accounted for 43.8% (n = 85) of all porcine strains and for 55.4% (n = 36) of the porcine strains, which exhibited haemolytic activity. These strains carried virulence genes by 65.9% (n = 56) and 80.6% (haemolytic E. coli, n = 29), respectively. The E. coli O-types O139:K82 and O141:K85 were significantly associated with the adhesin gene F18, and O149:K81 with the F4 gene. In this context, detection of the gene encoding F18 was coupled predominantly with the genes responsible for the production of the toxins ST-I, ST-II and Stx2, and the F4 gene with those of the enterotoxins ST-I, ST-II and LT. Both virulence patterns were detected more pronounced in E. coli strains with haemolytic activity. Fifty-six of a total of 83 E. coli isolates originating from calves were O-typed as O101 (O101:K28, O101:K30, O101:K32; n = 29), O78:K80 (n = 23), and O9:K35 (n = 4). Most of the E. coli O78:K80 strains carried the F17 gene (69.6%, n = 16). Virulence genes encoding for F4, F5 or ST-I were detected only in single cases. Intimin and Shiga toxin genes that are present in enterohaemorrhagic E. coli (EHEC) were not detected.
authors.affiliation: Chemisches und Veterinäruntersuchungsamt Stuttgart, Fellbach, Germany. reinhard.sting@cvuas.bwl.de
authors.forename: R
authors.initials: R
authors.lastname: Sting
authors.forename: M
authors.initials: M
authors.lastname: Stermann
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001426:Bacterial Proteins / Q000235:genetics; D001427:Bacterial Toxins / Q000235:genetics; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis* / Q000382:microbiology; D003967:Diarrhea / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D004768:Enterotoxins / Q000235:genetics; D004926:Escherichia coli / Q000472:pathogenicity*; D016133:Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012703:Serotyping / Q000662:veterinary; D013552:Swine; D013553:Swine Diseases / Q000175:diagnosis* / Q000382:microbiology; D014774:Virulence / Q000235:genetics; D014886:Weaning
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004768:Enterotoxins