Is Tea Tree Oil Really Effective?

The Efficacy of Tea Tree Oil.
Summary of Microbiological Testing:
Independent microbiological testing of Australian Tea Tree Oil has shown the minimum inhibitory concentration (MIC) of the oil against a variety of micro-organisms (ie the lowest concentration which will inhibit the growth of a specified micro-organism), several hundred in vitro tests have been conducted using Pharmaceutical Grade Australian Tea Tree Oil.
In summary, it may be concluded that Australian Tea Tree Oil is active against a wide range of micro-organisms including the following:

GRAM POSITIVE BACTERIA

MIC(%v/v)

Staphylococcus aureus

0.5-1.0

Staphylococcus epidermidis

0.5-1.0

Streptococcus pneumoniae

0.25

Streptococcus faecalis

1.0

Streptococcus pyrogenes

1.0

Streptococcus agalactiae

1.25

Propionibacterium acnes

0.75

Beta haemolytic streptococcus

0.5

GRAM NEGATIVE BACTERIA

MIC(%v/v)

Escherichia coli

0.5

Klebsiella pneumoniae

1.0-2.0

Citrobacter spp.

0.5-1.0

Shigella sonnei

0.5

Proteus mirabilis

0.5-1.0

Legionella spp.

0.75-1.0

Pseudomonas aeruginosa

2.0

FUNGI

MIC(%v/v)

Trichophyton mentagrophytes

0.75

Trichophyton rubrum

0.5

Aspergillus niger

1.0

Aspergillus flavus

0.25

Candida albicans

0.5

Microsporum canis

1.0

Microsporum gypseum

1.0

Thermoactinomycetes vulgarus

1.25

U.S.P. XXI Preservative Challenge Test:

Pass (0.8%)

B.P. (1980) Preservative Challenge Test:

Pass (0.8%)

Therapeutic Goods Act (TGA) Test:

TGA Hospital Grade Disinfectant Option A:

Pass (pure oil)

TGA Antiseptic Grade Option D:

Pass (5% cream)

TGA Hospital Grade Dirty Disinfectant Option B:

Pass (pure oil)