Brief exposure to hyperoxia is associated with reduced Plasmodium falciparum in vitro tolerance to Dihydroartemisinin.

The ring-stage survival assay (RSA) is a valuable tool for assessing in vitro Plasmodium falciparum tolerance to Dihydroartemisinin. However, laboratories with unreliable or no access to premixed commercial gas may not perform the RSA under the recommended physiological normoxia. We measured survival rates of ART-sensitive and ART-resistant strains in the normoxic commercial gas and hyperoxic candle jar gas. RSA read-outs for ART-resistant strains were significantly lower (p<0.05) under hyperoxia compared to physiological normoxia, whereas those of ART-sensitive strains were unaltered. These findings have important implications for interlaboratory comparison of RSA data and understanding the mechanisms of resistance to endoperoxide drugs.