ACTIVITY OF METRONIDAZOLE, AZITHROMYCIN AND 3 BENZIMIDAZOLES ON GIARDIA-LAMBLIA GROWTH AND ATTACHMENT TO A HUMAN INTESTINAL-CELL LINE

Background: Attachment of Giardia lamblia trophozoites to enterocytes is essential for colonization of the small intestine and is considered a prerequisite for Giardia-induced enterocyte damage. Inhibition of a ttachment may therefore have therapeutic potential. Methods: Enterocyt e-like differentiated Caco-2 cells were used as a biologically appropr iate attachment surface to determine the effect of three benzimidazole compounds (albendazole, mebendazole and thiabendazole), azithromycin and metronidazole on Giardia attachment. The results were compared wit h the ability for each drug to inhibit Giardia growth, measured using [H-3]-thymidine uptake. Results: The benzimidazoles inhibited Giardia attachment at much lower concentrations than did metronidazole. Howeve r, metronidazole was a much more potent inhibitor of growth than any o f the benzimidazoles. Azithromycin did not significantly impair Giardi a attachment or growth. The benzimidazoles decrease attachment but are less giardiacidal than metronidazole. Conclusion: This model appears useful for testing potential antigiardial compounds and investigating mechanisms of drug action.