ISOLATION, SEROTYPES, AND VIRULENCE-ASSOCIATED PROPERTIES OF YERSINIA-ENTEROCOLITICA FROM THE TONSILS OF SLAUGHTER HOGS

The objectives of this study were to determine the carriage rate of Ye rsinia enterocolitica in the tonsils of slaughter hogs, and to charact erize them with regard to phenotypic and virulence-associated properti es. Of 202 pigs examined from an abattoir in Prince Edward Island, 85 were culture positive for Y. enterocolitica. Sixty-seven percent of is olates belonged to serotype O:3, and 20% were serotype O:5. All isolat es produced urease and 95% of O:3 isolates showed virulence-associated characters of autoagglutination at 37 degrees C and lack of fermentat ion of esculin and salicin, All isolates were tested for crystal viole t binding, calcium dependency, and virulence plasmids. Eight isolates (5 belonging to serotype O:3, 2 belonging to O:5,27, and 1 belonging t o O:7,8) were tested in addition for the production of heat-stable ent erotoxin (ST), and iron-chelating siderophores. Of the 57 O:3 isolates , 93% were positive for crystal violet binding and calcium dependency and 98% possessed a 40-45 MDa plasmid, Four of the 5 O:3 isolates test ed for ST related to Escherichia coli STa in a commercial enzyme immun oassay were positive. Six of the 8 isolates belonging to 3 different s erotypes produced large orange halos around the colonies on a chrome-a zurol-s agar assay medium, for siderophores, Antimicrobial susceptibil ity tests of all 85 isolates against 16 drugs showed 100% susceptibili ty against 12 drugs, including trimethoprim-sulfamethoxazole and tetra cycline.