Increase of activity of tioconazole against resistant microorganisms by the addition of butylated hydroxyanisole

Tioconazole (TCZ) killed resistant Candida albicans in less than 3 min, after the addition of butylated hydroxyanisole (BHA), a phenolic antioxidant, at subinhibitory concentrations. The bactericidal activity was also rapid against resistant Escherichia coli. BHA increased the TCZ activity in RPMI 1640 medium 18 times against ten strains of resistant C albicans as judged by MIC and increased the activity 43 times against ten resistant E coli strains. BHA at subinhibitory concentrations promoted the reduction of C albicans virulence by reducing 180 times the hyphal cells of TCZ and decreasing hydrophobicity. The synergy could be due to changes in cellular permeability because of increased leakage of cellular enzymes. (C) 2003 Published by Elsevier B.V. and the International Society of Chemotherapy.