Isolation from food and characterization by virulence tests of Yersinia enterocolitica associated with an outbreak

A Yersinia enterocolitica outbreak associated with "pork cheese" is described. The phosphate-sorbitol-bile method was combined with KOH pretreatment for isolation of the agent from food. The pathogenicity of the food and faecal isolates was verified with virulence tests: the calcium-dependent populations carried a 42 Mdal plasmid, showed HEp-2 penetration and disintegration and were autoagglutinable.