Blastocystis hominis: neutral red supravital staining and its application to in vitro drug sensitivity testing

A simple in vitro drug sensitivity testing system for Blastocystis hominis clinical isolates was developed. Application of supravital staining by neut ral red allowed quantitative viability assessment. Four xenic cultures, iso lated from human sources, were grown in modified monophasic Robinson's medi um and tested for sensitivities to nine available drugs. Assessment was don e using the cell-count method from air-dried preparations after supravital staining with neutral red. Also, the light absorbence method was evaluated. Trimethoprim, metronidazole, quinacrine, tetracycline, paromomycin, and tw o new antiprotozoal drugs, nitazoxanide and deacetyl-nitazoxanide, showed c ytostatic or cytocidal effects on all or some Blastocystis isolates. Chloro quine and sulphamethoxazole did not demonstrate any effect at the concentra tions studied.