Factors affecting detection of Yersinia enterocolitica heat-stable enterotoxin by the infant mouse test

Production of bacteriocin-like antagonism by clinical isolates of Yersinia enterocolitica

Fourteen clinical isolates of Yersinia enterocolitica serotype O:3 and four well-documented virulent strains of serotypes O:3, O:8, and O:9 were biotyped and examined for plasmid-associated autoagglutination and calcium dependency and for epithelial cell adherence. These strains were tested for the production of bacteriocin-like antagonism by using tryptone soya blood agar at room temperature and at 37 degrees C. By using the cross-streaking method, three clinical isolates produced inhibitory substances at room temperature. These substances were active against a variety of clinical isolates and their plasmid-cured derivatives at both room temperature and 37 degrees C. The inhibition was easier to read after incubation of the cross-streaked plate at 37 degrees C. The inhibition patterns indicate that two of the three producer strains appear to recognize potentially virulent O:3 strains, with or without the virulence plasmid.