The influence of tea tree oil (Melaleuca alternifolia) on fluconazole activity against fluconazole-resistant Candida albicans strains

Biomed Res Int. 2015;2015:590470. doi: 10.1155/2015/590470. Epub 2015 Feb 4.


The aim of this study was to evaluate the activity of fluconazole against 32 clinical strains of fluconazole-resistant Candida albicans, and C. albicans ATCC 10231 reference strain, after their exposure to sublethal concentrations of tea tree oil (TTO) or its main bioactive component terpinen-4-ol. For all tested fluconazole-resistant C. albicans strains TTO and terpinen-4-ol minimal inhibitory concentrations (MICs) were low, ranging from 0.06% to 0.5%. The 24-hour exposure of fluconazole-resistant C. albicans strains to fluconazole with sublethal dose of TTO enhanced fluconazole activity against these strains. Overall, 62.5% of isolates were classified as susceptible, 25.0% exhibited intermediate susceptibility, and 12.5% were resistant. For all of the tested clinical strains the fluconazole MIC decreased from an average of 244.0 μg/mL to an average of 38.46 μg/mL, and the fluconazole minimal fungicidal concentrations (MFC) decreased from an average of 254.67 μg/mL to an average of 66.62 μg/mL. Terpinen-4-ol was found to be more active than TTO, and strongly enhanced fluconazole activity against fluconazole-resistant C. albicans strains. The results of this study demonstrate that combining natural substances such as TTO and conventional drug such as fluconazole, may help treat difficult yeast infections.

MeSH terms

  • Antifungal Agents / pharmacology
  • Candida albicans / drug effects*
  • Candidiasis / drug therapy*
  • Candidiasis / microbiology
  • Drug Resistance, Fungal / drug effects*
  • Fluconazole / pharmacology
  • Humans
  • Tea Tree Oil / pharmacology*


  • Antifungal Agents
  • Tea Tree Oil
  • Fluconazole