Sir.—In the report by Burchfield et al1 on intussusception associated with Yersinia enterocolitica gastroenteritis, the actual role of Y enterocolitica as the specific cause of gastroenteritis may have been suspected, but the characteristics of Y enterocolitica, isolated from the patient's stool culture, were not demonstrated, as biogroup, serogroup, and phage-type tests were not performed.
Furthermore, no attempt was made to arrive at a serodiagnosis by means of the Y enterocolitica strain recovered from the patient during the convalescent period.
In citing Marks et al,2 Burchfield and colleagues1 failed to mention that only Y enterocolitica biotype 4, serogroup 0:3, was associated with infection in the Canadian experience, whereas Y enterocolitica non-0:3 serogroups were not considered pathogenic for childhood diarrhea on the basis of short duration of excretion, infrequent spread to contacts, and lack of humoral antibodies; serogroups 0:8 and 0:9 were not isolated by Marks et al.2