BLASTOCYSTIS-HOMINIS IN HUMAN IMMUNODEFICIENCY VIRUS-RELATED DIARRHEA

Background: A wide variety of bacterial, viral, and parasitic pathogens can cause severe diarrhea in patients with advanced human immunodeficiency virus (HIV) infection. Conflicting evidence exists as to whether Blastocystis hominis should also be included among the infectious agents capable of causing HIV-related diarrhea. Methods: We determined the prevalence and clinical significance of B. hominis in a cohort of 262 patients with HIV infection, presenting at the infectious diseases department of a tertiary referral university hospital in northern Germany. Results: B. hominis was detected in stool samples of 99 patients (38%). The isolation rate varied highly between the different groups. Homosexual men (43%; odds ratio (OR), 2.1;p = 0.01) had a higher detection rate than patients from other risk groups (26%), and patients with acquired immunodeficiency syndrome (46%; OR, 1.8; p = 0.03) were more likely to carry B. hominis than patients in earlier stages of their HIV infection (32%). An association with clinical symptoms was not evident. Presence of B. hominis, however, was frequently associated with the concurrent isolation of other enteric pathogens or apathogenic parasites. Conclusions: The data suggest that the isolation of B. hominis does not justify treatment even in symptomatic, severely immunocompromised patients. Most patients will either have spontaneous resolution of symptoms or successful identification of other infectious or noninfectious etiologies. Therapy should be limited to patients with persistent unexplained symptoms after a thorough evaluation and a complete screening for alternative etiologies, including the use of endoscopic procedures and the careful examination of multiple specimens.