Susceptibility of transient and commensal skin flora to the essential oil of Melaleuca alternifolia (tea tree oil)

Am J Infect Control. 1996 Jun;24(3):186-9. doi: 10.1016/s0196-6553(96)90011-5.


Objectives: The purpose of this study was to determine the susceptibility of a range of transient and commensal skin flora to the essential oil of Melaleuca alternifolia, or tea tree.

Methods: A modified broth microdilution method was used. Polyoxyethylene sorbitan mono-oleate detergent was added to the test medium to enhance solubility of the tea tree oil.

Results: Serratia marcescens had the lowest minimum inhibitory concentration (MIC90) of 0.25%. The highest MIC90 was 3% for Pseudomonas aeruginosa. The lowest minimum bactericidal concentration (MBC90) was 0.25% for S. marcescens and Klebsiella pneumoniae, whereas the highest was 8% for Staphylococcus capitis.

Conclusions: S. aureus and most of the gram-negative bacteria tested were more susceptible to tea tree oil than the coagulase-negative staphylococci and micrococci. These results suggest that tea tree oil may be useful in removing transient skin flora while suppressing but maintaining resident flora.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Gram-Negative Bacteria / drug effects*
  • Gram-Positive Bacteria / drug effects*
  • Humans
  • Microbial Sensitivity Tests
  • Oils, Volatile / pharmacology
  • Plant Oils / pharmacology*
  • Skin / microbiology*


  • Oils, Volatile
  • Plant Oils