Sodium Metabisulfite Inhibits Trophozoite Growth through Thiamine Depletion.

keratitis (AK) is a severe infection of the cornea. Prevention and treatment are difficult due to the inefficacy of currently available compounds. The impact of many commonly used compounds for routine examinations of is unexplored but might offer insight useful in combatting AK. In this study, we demonstrate that sodium metabisulfite, a common preservation constituent of eye care solutions, was found to be active against trophozoites at concentrations lower than that commonly found in eye drops (IC 0.03 mg/mL). We demonstrate that sodium metabisulfite depletes thiamine from growth medium and that is a thiamine auxotroph, requiring thiamine salvage for growth. The inhibitory effects of sodium metabisulfite can be overcome by thiamine supplementation. These results are consistent with the lack of key enzymes for thiamine biosynthesis in the genome of , an area which might prove exploitable using new or existing compounds. Indeed, this study highlights sodium metabisulfite as a useful inhibitor of trophozoites in vitro and that it acts, at least in part, by limiting available thiamine.