title: Susceptibility of transient and commensal skin flora to the essential oil of Melaleuca alternifolia (tea tree oil).
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Microbiology, University of Western Australia.
authors.forename: K A
authors.initials: KA
authors.lastname: Hammer
authors.forename: C F
authors.initials: CF
authors.lastname: Carson
authors.forename: T V
authors.initials: TV
authors.lastname: Riley
mesh_terms: D006090:Gram-Negative Bacteria / Q000187:drug effects*; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009822:Oils, Volatile / Q000494:pharmacology; D010938:Plant Oils / Q000494:pharmacology*; D012867:Skin / Q000382:microbiology*
chemical_list: D009822:Oils, Volatile; D010938:Plant Oils