Therapy with
metronidazole is the recommended option in
giardiasis. However, some clinical trial reports suggest the appearance of drug resistance to explain therapeutic failure. Several investigations have been carried out on the effect of probiotic microorganisms for preventing or treating
gastrointestinal diseases, but little is known about their efficacy against protozoal
infections. The principal objective of our study was to evaluate the efficacy of Saccharomyces boulardii against
Giardia lamblia infections. A double-blind, placebo-controlled study was carried out on adult patients with
giardiasis. Group 1 (30 patients) included
metronidazole 750 mg 3 times daily along with S. boulardii capsules (250 mg b.i.d. orally) for 10 d while group 2 (35 patients) was treated with
metronidazole 750 mg 3 times daily and with empty capsules as placebo for 10 d. Patients were re-examined at 2 and 4 weeks
after treatment, and stool examinations were performed. At week 2, G. lamblia
cysts were detected in 6 cases (17.1%) of group 2 and none in group 1. At the end of the fourth week, presence of the
cysts continued in the same 6 cases in group 2 (control group). These findings indicated that S. boulardii may be effective in treating
giardiasis when combined with
metronidazole therapy.