Yersinia enterocolitica: serotypes and biotypes isolated from humans and the environment in Quebec, Canada.

Thirty-one strains of Yersinia enterocolitica were isolated from food and surface water. During the period of January 1975 to June 1977, 157 strains from 143 human cases were also isolated. Among the different serotypes from nonhuman sources, serotypes 6,30 and 4,32 were the most common. Serotype 4,32 was present only in food and not in water. Serotype 3 was isolated only from humans. Among the different serotypes from human cases, 73.9% belonged to serotype 3. Only serotype 3 was isolated from children under 4 years old. The presence of other serotypes increased and that of serotype 3 decreased in frequency as the age progressed. No serotype 3 was isolated from human cases aged 50 years and more.