BLASTOCYSTIS-HOMINIS INFECTION AND INTESTINAL INJURY

Blastocystis hominis is an enteric protozoan associated with clinical illness. To determine the prevalence of intestinal injury in patients with B. hominis infection, the authors prospectively evaluated 18 pati ents with B. hominis infection by endoscopy and a test of intestinal p ermeability. Seventeen patients had gastrointestinal symptoms. Colonic mucosa appeared normal by lower endoscopy in 12 of 13 patients, and w as friable slightly in 1. Duodenal mucosa was normal by upper endoscop y in nine patients. Pathologic examination of mucosal biopsy specimens did not demonstrate evidence of mucosal invasion. 51Cr-edetic acid (5 1Cr-EDTA) was given to the 18 patients with stools positive for B. hom inis and to 32 healthy control subjects. Approximately 100 uCi of 51Cr -EDTA was given orally after an overnight fast, and urine was collecte d for the following 24 hours. Mean 24-hour urinary excretion of 51Cr-E DTA, calculated as a percent of the administered dose, was 1.31% (0.34 -2.76%) in patients with B. hominis infection and 1.99% (0.59-3.48%) i n the control subjects. The intestinal permeability to 51Cr-EDTA in bl astocystis-infected individuals was not increased, but was decreased s ignificantly compared with healthy subjects (p < 0.005). Therefore, in a group of symptomatic patients with B. hominis infection, endoscopy typically did not show evidence of significant intestinal inflammation , and results of intestinal permeability testing with 51Cr-EDTA did no t suggest impaired barrier function of the intestinal mucosa. The clin ical literature on B. hominis infection and intestinal injury is revie wed.