BLASTOCYSTIS-HOMINIS IN HUMAN IMMUNODEFICIENCY VIRUS-RELATED DIARRHEA

Background: A wide variety of bacterial, viral, and parasitic pathogen s can cause severe diarrhea in patients with advanced human immunodefi ciency virus (HIV) infection. Conflicting evidence exists as to whethe r Blastocystis hominis should also be included among the infectious ag ents capable of causing HIV-related diarrhea. Methods: We determined t he prevalence and clinical significance of B. hominis in a cohort of 2 62 patients with HIV infection, presenting at the infectious diseases department of a tertiary referral university hospital in northern Germ any. 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 detec tion rate than patients from other risk groups (26%), and patients wit h acquired immunodeficiency syndrome (46%; OR, 1.8; p = 0.03) were mor e likely to carry B. hominis than patients in earlier stages of their HIV infection (32%). An association with clinical symptoms was not evi dent. Presence of B. hominis, however, was frequently associated with the concurrent isolation of other enteric pathogens or apathogenic par asites. Conclusions: The data suggest that the isolation of B. hominis does not justify treatment even in symptomatic, severely immunocompro mised patients. Most patients will either have spontaneous resolution of symptoms or successful identification of other infectious or noninf ectious etiologies. Therapy should be limited to patients with persist ent unexplained symptoms after a thorough evaluation and a complete sc reening for alternative etiologies, including the use of endoscopic pr ocedures and the careful examination of multiple specimens.