A new vial microassay to screen antiprotozoal drugs

A new microassay to screen compounds having activity against Entamoeba histolytica, Giardia lamblia and Trichomonas vaginalis is described. The procedure is performed in 1 mL capacity glass screw-capped vials, which have an external cylindrical shape and a conical interior. Vials were filled with 950 μL of a trophozoite suspension (2 × 104 to 2 × 105/mL) and 50 μL of the test substance at a final concentration of 1.6-50 μg/mL. Emetine, metronidazole, tinidazole, secnidazole, ornidazole and dimetridazole were used as standards. The preparations were incubated at 36 °C for 24-48 h and the concentration of each drug producing 50% growth inhibition was calculated. All results obtained with this vial micromethod were within the ranges reported by other authors in each particular case. The vial assay method combines the advantages of a microassay, requiring small quantities of test substances and with the functionality of assays in culture tubes.