Treatment of Blastocystis hominis in the Absence of Diarrhea

Understanding Blastocystis hominis

• The pathogenicity of Blastocystis hominis remains controversial, and in the absence of other pathogens, it may only be clinically relevant if symptoms persist, as suggested by the Infectious Diseases Society of America 1, 2

Diagnostic Considerations

• Reporting semi-quantitative results (rare, few, many) may help determine clinical significance, according to the Clinical Infectious Diseases guidelines 1, 2

When to Consider Treatment

• No other pathogen is identified as the cause of symptoms, which is a consideration for treatment, as indicated by the Clinical Infectious Diseases guidelines 1

When NOT to Treat

• Patients with incidental finding of Blastocystis without diarrhea or other GI symptoms do not require treatment, as recommended by the Clinical Infectious Diseases guidelines 1, 2
• In most people with acute watery diarrhea and without recent international travel, empiric antimicrobial therapy is not recommended regardless of the pathogen, according to the Clinical Infectious Diseases guidelines 3

Clinical Pitfalls to Avoid

• Treating asymptomatic carriers unnecessarily contributes to antimicrobial resistance without providing therapeutic benefit, as noted by the American College of Physicians 4
• Not completing the full course of antiparasitic treatment when treatment is indicated, which may lead to treatment failure, as cautioned by the American Medical Association 5