From the Guidelines
Blastocystis infection should be treated with metronidazole at a dose of 500-750 mg three times daily for 5-10 days in patients with persistent diarrhea, as recommended by the 2017 Infectious Diseases Society of America clinical practice guidelines 1.
Diagnosis and Treatment
For symptomatic Blastocystis infection causing persistent diarrhea, the following treatments are considered:
- Metronidazole: 500-750 mg three times daily for 5-10 days
- Alternative treatments:
- Trimethoprim-sulfamethoxazole (160/800 mg twice daily for 7 days)
- Nitazoxanide (500 mg twice daily for 3 days)
- Paromomycin (25-35 mg/kg/day in three divided doses for 7 days) According to the guidelines, treatment should be considered only when symptoms are present and other causes of diarrhea have been ruled out, as many people carry Blastocystis without symptoms 1.
Prevention and Management
During treatment, patients should:
- Maintain good hydration
- Consider probiotics to help restore gut flora Preventive measures include:
- Proper handwashing
- Safe food handling
- Drinking clean water As Blastocystis can disrupt the intestinal barrier and alter gut microbiota, which may explain its association with gastrointestinal symptoms in some individuals, follow-up stool testing may be warranted if symptoms persist after treatment 1.
From the Research
Blastocystis Diarrhea
- Blastocystis infections can cause symptoms such as diarrhea, abdominal pain, and nausea-vomiting, and therapy should be limited to patients with persistent symptoms and a complete workup for alternative etiologies 2.
- The goal of treatment is to alleviate symptoms and eradicate the parasite, with metronidazole and Saccharomyces boulardii being potential treatment options 2, 3.
- However, there is evidence to suggest that metronidazole may not be effective in all cases, with some studies reporting treatment failure and metronidazole-resistant strains 4, 5.
- Alternative treatment options, such as trimethoprim-sulfamethoxazole, have shown promise in eradicating Blastocystis and alleviating symptoms 3, 6.
Treatment Options
- Metronidazole: commonly used to treat Blastocystis infections, but may not be effective in all cases 2, 3, 5.
- Saccharomyces boulardii: a potential treatment option that has shown beneficial effects in reducing symptoms and eradicating the parasite 2.
- Trimethoprim-sulfamethoxazole: an alternative treatment option that has been shown to be effective in eradicating Blastocystis and alleviating symptoms 3, 6.
Efficacy of Treatment
- Clinical cure rates have been reported to be higher in patients treated with Saccharomyces boulardii or metronidazole compared to those who received no treatment 2.
- Parasitological cure rates have also been reported to be higher in patients treated with metronidazole or Saccharomyces boulardii 2.
- However, treatment failure and metronidazole-resistant strains have been reported, highlighting the need for alternative treatment options 4, 5.