Yersinia enterocolitica: guidelines for serologic diagnosis of human infections.

In the United States the diagnosis of human infection due to Yersinia enterocolitica is usually achieved by recovery of the microorganism. Serology as a diagnostic adjunct has been used minimally because of the absence of sufficient guidelines for interpretation of agglutinin titers. The serologic response among three groups of subjects (control, febrile, and infected) was assessed, and the serologic diagnosis of Y. enterocolitica infection was found to be multifactorial. Except in well-circumscribed outbreaks, agglutinin titers must be interpreted on an individual basis, taking into consideration the patient's age and underlying disease and the antibiotics and immunosuppressive agents being administered. Other factors affecting interpretation are the prevalence of a given serogroup of Y. enterocolitica in the community, the nature of antigen used, and the awareness of prozone phenomena. Agglutinin titers in the range of 1:128 in previously normal, healthy individuals are suggestive of infection; negative or minimal titers (greater than or equal to 1:32) do not rule out yersiniosis in an infant or in an immunosuppressed patient. Serology appears to be a secondary alternative to the more definitive cultural endeavors for use in diagnosis.