Susceptibility of Propionibacterium acnes to the essential oil of Melaleuca alternifolia

The susceptibility of 32 strains of Propionibacterium acnes to the essential oil of Melaleuca alternifolia, tea tree oil, was examined using a broth dilution method. The minimum bactericidal concentration of tea tree oil for five strains was 0.25% or less while, for the remainder, it was 0.50%.