Activity of nitazoxanide alone and in combination with azithromycin and rifabutin against Cryptosporidium parvum in cell culture

The in vitro activity of nitazoxanide alone and in combination with azithro mycin and rifabutin was investigated against four clinical isolates of Cryp tosporidium parvum, The susceptibility tests were performed by inoculation of the isolates on toe cell monolayers and determination of the parasite co unt after 48 h incubation at 37 degrees C. The culture medium was supplemen ted with Dulbecco's modified Eagle's medium containing serial dilutions of each agent. Antibiotic-free plates were used as controls, Experiments were performed in triplicate. Nitazoxanide showed moderate anticryptosporidial a ctivity: it suppressed the growth of parasites by >50% at 8 mg/L, A parasit e reduction of 79.8-83.9% was observed when nitazoxanide 8 mg/L was combine d with azithromycin 8 mg/L and rifabutin 8 mg/L. The study suggests that ni tazoxanide may be active in inhibiting C. parvum growth in vitro upon combi nation with azithromycin or rifabutin.