The subject invention is directed to the treatment of infections caused by fungi which are resistant to standard antifungal drugs such as fluconazole. The treatment method involves administering to the sufferer an effective amount of an agent that suppresses the activity of the fungal (H+)-ATPase pump (Pma1p). Such agents may take the form of: a) 2-phenyl-1,2-benzisoselenazol-3(2H)-one, commonly referred to as ebselen and depicted by Formula I, or b) 2-phenyl-1,2-benzisoselenazol-3(2H)-one 1-oxide, commonly referred to as ebselen se-oxide and depicted by Formula II, or pharmaceutically acceptable salts thereof. Opportunistic fungal infections include those which are systemic and those which are superficial and are caused by species of fungi belonging to the genus Candida, Aspergillus, Pneumocystis, Tinea, Blastomyces, Cryptococcus, Histoplasma, Sporotrichum, Malassezia, Hansenula, Rhodotorula, Trichosporon, as well as others.