``Before registering a health-care antiseptic,
the Food and Drug Administration of the USA requires a list of all the organisms that are killed by the antiseptic.
Riley`s team designed experiments to test the susceptibility of organisms to tea tree oil.
They aimed to identify the minimum concentrations of oil that would inhibit growth or kill particular micro-organisms.
They tested many micro-organisms including:
* Escherichia coli,
which causes gastroenteritis
* Pseudomonas aeruginosa,
a penicillin-resistant bacterium that infects wounds,
and the urinary and respiratory tracts
* Methicillin-resistant strains of Staphylococcus aureus (Golden staph),
a major cause of hospital-acquired infections
* Streptococcus and Staphylococcus species,
which cause skin infections including impetigo
* Propionibacterium acnes,
which plays a role in acne
* Candida albicans,
a fungus that causes thrush infections.
The team grew the organisms in several warm broths containing varying concentrations of tea tree oil for 24 hours.
They found that the growth of most of the organisms was inhibited at an oil concentration of 0.25%v/v (volume/volume,
ie 0.25ml of tea tree oil added to 99.75ml of broth).
Most of the organisms died at 0.50% while an oil concentration of 3.0% was needed to kill the penicillin-resistant bacteria Pseudomonas aeruginosa.
All of these findings have been published in international journals.
Tea tree oil is finding effective uses for eczema,
oral and dental mouth sores,
and for it`s solvent capabilities.``