From the Research
The treatment for symptomatic Blastocystis hominis infections typically involves antiparasitic medications, with metronidazole being the first-line therapy at a dose of 500-750 mg three times daily for 7-10 days, as supported by the most recent study 1.
Treatment Options
- Metronidazole: 500-750 mg three times daily for 7-10 days
- Alternative effective treatments: trimethoprim-sulfamethoxazole (TMP-SMX) at a dose of 160/800 mg twice daily for 7 days, or nitazoxanide 500 mg twice daily for 3 days
- Combination treatments for patients who fail to respond to initial therapy: metronidazole plus paromomycin (25-35 mg/kg/day in three divided doses for 7 days)
Important Considerations
- Treatment is generally only recommended for patients with persistent gastrointestinal symptoms when other causes have been ruled out and Blastocystis is the only pathogen identified
- Many infections are asymptomatic and may not require treatment
- Supportive care with hydration and probiotics may help manage symptoms while undergoing antiparasitic therapy
- The rationale for treatment is that Blastocystis can cause gastrointestinal symptoms by disrupting the gut microbiota, causing low-grade inflammation, and producing proteases that can damage the intestinal barrier, as discussed in 2 and 3
Evidence Summary
The most recent study 1 found that metronidazole has a low efficacy in eradicating Blastocystis hominis in symptomatic patients, with a microbiological response rate of 48.4%. Another study 4 found that metronidazole and Saccharomyces boulardii have potential beneficial effects in B. hominis infection, with a clinical cure rate of 77.7% and 66.6%, respectively. However, the study 3 highlights the lack of efficacy of several commonly used antimicrobial regimens in the treatment of Blastocystis and the chronic nature of some infections.