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 attachment may therefore have therapeutic potential.
Methods: Enterocyte-like differentiated Caco-2 cells were used as a biologically appropriate attachment surface to determine the effect of three benzimidazole compounds (albendazole, mebendazole and thiabendazole), azithromycin and metronidazole on Giardia attachment. The results were compared with the ability for each drug to inhibit Giardia growth, measured using [3H]-thymidine uptake.
Results: The benzimidazoles inhibited Giardia attachment at much lower concentrations than did metronidazole. However, metronidazole was a much more potent inhibitor of growth than any of the benzimidazoles. Azithromycin did not significantly impair Giardia 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.