Objectives: Thirty isolates of Pseudomonas aeruginosa, 15 isolates of Pseudomonas putida and 11 isolates of Pseudomonas fluorescens were tested for susceptibility to tea tree oil (TTO), the essential oil of Melaleuca alternifolia, and the components terpinen-4-ol, alpha-terpineol, cineole, gamma-terpinene and rho-cymene.
Methods: MICs were determined by broth microdilution in Mueller-Hinton medium supplemented with 0.002% (v/v) Tween 80.
Results: The MIC90 of TTO for all isolates tested was 4% (v/v) or less. Susceptibility to components tested varied between species.
Conclusions: Pseudomonas spp. are susceptible to TTO and some of its components although they are less susceptible than many other bacteria tested previously.