Oregano oil kills yeast (Candida albicans), and when mice were infected with 5 times the lethal dose of the infectious Candida yeast, 80% of them survived.
Antifungal activities of origanum oil against Candida albicans.
Manohar V, Ingram C, Gray J, Talpur NA, Echard BW, Bagchi D, Preuss HG.
Mol Cell Biochem., 2001 Dec, 228(1-2), 111-117.
http://www.ncbi.nlm.nih.gov/pubmed/11855736