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Treatment
The clinical significance of Blastocystis spp. is controversial.
Treatment with metronidazole* at various doses has been reported, for example (adults):
- 250 mg to 750 mg metronidazole* orally 3 times daily for 10 days
- 1500 mg metronidazole* orally once daily for 10 days
Note: Lack of response to metronidazole has been noted in some areas (Yakoob et al., Br J Biomed Sci 2004;61:75).
Treatment with trimethoprim (TMP)*/sulfamethoxazole (SMX)* at various doses has been reported, for example (adults):
- 6 mg/kg TMP*, 30 mg/kg SMX* once daily for 7 days
- 320mg TMP*, 1600 mg SMX* once daily for 7 days
- 160 mg TMP*, 800 mg SMX* twice daily for 7 days
Treatment with nitazoxanide* has been shown to be effective in clearing organisms and improving symptoms at the following doses:
- Adults, 500 mg nitazoxanide* orally twice daily for 3 days.
- Children, 200 mg nitazoxanide* orally twice daily for 3 days in patients aged 4–11 years, and 100 mg nitazoxanide* orally twice daily for 3 days in patients aged 1–3 years.
Tinidazole*, paromomycin*, iodoquinol*, and ketoconazole* have also been used for clearing Blastocystis, as presented in case reports or small series (see references).
*Not FDA-approved for this indication.
References
- Stensvold CR, Smith HV, Nagel R, Olsen KE, Traub RJ. Eradication of Blastocystis carriage with antimicrobials: reality or delusion? J Clin Gastroenterol 2010;44:85-90.
- Tan KS. New insights on classification, identification, and clinical relevance of Blastocystis spp. Clin Microbiol Rev 2008:639-65.
- Rossignol JF, Kabil SM, Said M, Samir H, Younis AM. Effect of nitazoxanide in persistent diarrhea and enteritis associated with Blastocystis spp.. Clin Gastroenterol Hepatol 2005 Oct;3(10):987-91.
- Diaz E, Mondragon J, Ramirez E, Bernal R. Epidemiology and control of intestinal parasites with nitazoxanide in children in Mexico. Am J Trop Med Hyg 2003;68:384-5.
- Nigro L, Larocca L, Massarelli L, Patamia I, Minniti S, Palermo F, Cacopardo B. A placebo-controlled treatment trial of Blastocystis spp. infection with metronidazole. J Travel Med 2003;10:128-30.