Sensitivity in vitro of Giardia intestinalis to dyadic combinations of azithromycin, doxycycline, mefloquine, tinidazole and furazolidone.

The new macrolide antibiotic, azithromycin, produced significant growth inhibition of Giardia intestinalis at 100 micrograms/ml, but adherence inhibition was significant at concentrations as low as 1 microgram/ml for the two strains used in these experiments. The dyadic combinations of azithromycin-furazolidone, doxycycline-mefloquine, doxycycline-tinidazole and mefloquine-tinidazole were synergistic for inhibition of adherence. These results suggest that these dyadic combinations may be worthy of consideration for chemotherapy of recalcitrant giardiasis.