Intestinal protozoa infections among patients with ulcerative colitis: prevalence and impact on clinical disease course.

BACKGROUND Epidemiological and microbiologic studies suggest that enteropathogenic microorganisms play a substantial role in the clinical initiation and relapses of inflammatory bowel disease. AIM To explore the prevalence of intestinal protozoa in patients with ulcerative colitis (UC) and its impact on clinical disease course. METHODS A total of 215 patients with definitive diagnosis of UC were studied. Fresh feces samples taken from all UC patients were examined immediately using trichrome-staining methods. RESULTS A total of 103 female and 112 male UC patients were analyzed. The mean age at diagnosis was 30.5 +/- 10.8 years. The prevalence of overall parasitic infections was 24% and distributed as follows: Blastocystis hominis in 22 patients (10%), Endolimax nana in 19 cases (9%), and Entamoebahistolytica in 11 cases (5%). A significantly increased frequency of protozoa infection was found in those patients with persistent activity and intermittent activity as compared to active than inactive group (p = 1 x 10(-7), OR 13.05, 95% CI 4.28-42.56, and p = 0.003, OR 1.42-14.47, respectively). Interestingly, this association remained significant when we compared the persistent activity group versus intermittent activity group (p = 0.003, OR 2.97, 95% CI 1.35-6.59). Subgroup analysis showed no association between protozoa infection (E. histolytica, B. hominis, and E. nana) and other clinical variables such as gender, extent of disease, extraintestinal complications, medical treatment and grade of disease activity. CONCLUSION The prevalence of intestinal protozoa infections in Mexican UC patients was 24% and these microorganisms could be a contributing cause of persistent activity despite medical treatment in our population.