Low frequency of chlamydial antibodies in patients with Crohn's disease and ulcerative colitis.

Serum samples from 55 patients with Crohn's disease and from 23 patients with ulcerative colitis were tested for antibodies to Chlamydia trachomatis immunotypes by a micro-immunofluorescence technique. Antibody titres of 1:8 or greater against several immunotypes were detected in 14.5% of patients with Crohn's disease and in 21.7% of those with ulcerative colitis. These figures resemble the incidence in a healthy, non-venereal-disease population. Furthermore, there was no correlation between the presence of antibody and such factors as duration of symptoms, localisation of disease, or disease activity. These findings indicate that there is no reason to believe that Crohn's disease involves chlamydiae or that examination for chlamydial antibody is helpful in diagnosis.