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Tea tree oil: a potential alternative for the management ofmethicillin-resistant Staphylococcus aureus (MRSA)

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Abstract

Complementary and alternative medicines occupy a privileged marketing position in many countries, including Australia, being able to carry low-level health claims while being relatively unfettered by regulatory requirements. Consequently, many enjoy widespread use for therapeutic purposes in the absence of definitive efficacy or safety data. Occasionally, the therapeutic properties of complementary and alternative medicines are scrutinised more closely and more thoroughly than their conventional counterparts, leading to the confirmation or discrediting of their properties.
Australian Infection
Control
Tea tree oil:
a
potential alternative for the management
of
methicillin-resistant
Staahvlococcus auvew
(MRSA)
Christine
F
Carson
"
BSc(Hons), PhD
Katherine
A
Hammer
"
BSc, PGDip, PhD
Syndie Messagev
"
BSc, PhD
Thomas
V
Riley
"'
BAppSc, MAppEpid, PhD, FRCPath,
FAAM, FASM
*
Microbiology, School of Biomedical
&
Chemical Sciences
The University of Western Australia, Crawley, WA
t
Division of Microbiology
&
Infectious Diseases
The Western Australian Centre for Pathology
&
Medical
Research, Nedlands, WA
Introduction
major components terpinen-4-01, a-terpinene and y-terpinene
that collectively comprise approximately 70% of the whole oil,
Complementary and alternative medicines occupy a privileged and delineates many of the physical characteristics such as
marketing position in many countries, including Australia, being relative density, refractive index and optical rotation.
able to carry low-level health claims while being relatively
-
unfettered by regulatory requirements. Consequently, many Notably, no specifications regarding the required levels of
enjoy widespread use
for
therapeutic purposes in the absence of biological activity have been set, in part because these are still
definitive efficacy or safety data. Occasionally, the therapeutic being
defined
and
in
Part there
has
been
no
Dronerties
of
comDlementarv and alternative medicines
are
evidence that the biological activities of oils that meet the
I
I
scrutinised
more
;losely
and
more
thoroughly
than
their
international standard vary significantly. However, as the
biological properties of tea tree oil become increasingly well-
conventional counterparts, leading to the confirmation or characterised and any potential for variation becomes apparent,
discrediting of their properties. this may become necessary.
While the scientific investigation of complementary and In contrast to the apparent robustness of the biological properties
alternative medicines is at a nascent stage in Australia, certain
of
tea
tree
oil
in
the
face
of
batch
to
batch
variation,
the
are
being investigated One
of
these
is
the
formulation of tea tree oil into ~roducts ma" dramaticallv affect
essential oil of
Melaleuca altemfolia,
also known as tea tree or its biological with
iertain
prod;ct
excipients
Jhown
Melaleuca
oil. Produced from steam distilled from the foliage of to compromise its antimicrobial activity5.
this Australian native ~lant. tea tree oil has been vromoted since
I
the 1920s as an antiseptic and disinfectant, more eifective and less
The
activity
of
tea
tree
is
the
most
established biological property of the oil, with activity
corrosive than the gold standard of the day, phenol or carbolic demonstrated against bacteria
',
fungi
lo
l3
and viruses IJ. Other
acid
'.
Its popularity dwindled during the era surrounding the biological properties described include anti-inflammatory
discovery and development of penicillins, and recurred only pr~perties'~,'%nd, possibly, anti-tumoural activity
17.
relatively recently during the natural product renaissance of the
late 1970s and 1980s. Today tea tree oil is available in many
cosmetic and toiletry products as well as a range of therapeutic
products.
Originally harvested from natural bush stands of
M. alternifolia,
tea tree oil is now produced on large-scale plantations, primarily
in north-eastern New South Wales. The physical and chemical
properties of tea tree oil may vary from batch to batch and are
influenced by many factors, including provenance, cultivation
conditions, production processes and storage conditions
*.
Quality control of these properties of this oil has been greatly
assisted by the development of an international standard for tea
tree oil3. The standard dictates compositional limits for
16
of the
approximately 100 terpene components of the oil, including the
Activity against methicillin-resistant
Staphylococcus auveus
(MRSA)
The first suggestion that tea tree oil may have had clinically
useful antimicrobial activity against MRSA was made in 1987 by
Walsh
&
Longstaff '"ho reported that these bacteria were
susceptible to the oil. No additional characterisation occurred
until 1995 when Carson
et al.
"
tested the susceptibility of
64
isolates of MRSA (32 mupirocin-resistant) and found them
uniformly susceptible, with MICs around 0.25% and MBCs of
0.5%. Several other groups have corroborated this activity '"',
leading to speculation that tea tree oil may be a useful agent for
the decolonisation of MRSA carriage or the treatment of skin
wounds infected with MRSA.
Vol
10
Issue
1
March
2005
Australian Infection Control
Some clinical data to support this hypothesis came from a pilot
study in which the efficacy of a 4% tea tree oil nasal ointment and
a 5% tea tree oil body wash was compared to conventional
treatment of mupirocin nasal ointment and Triclosan skin wash
for the decolonisation of MRSA in hospital inpatients
25.
This
small study, in which there were 15 patients in each group, did
not show a significant difference between the two treatment
groups; five patients and two patients were cleared, while three
and eight remained colonised in the tea tree oil and conventional
treatment groups, respectively. Five patients from the
conventional treatment group and seven from the tea tree oil
group did not complete the course of treatment. Use of the tea
tree oil nasal ointment resulted in reports of adverse events
ranging from mild swelling of the nasal mucosa to burning on
application, but no patient numbers were given. No adverse
events were recorded for either the tea tree oil body wash or the
mupirocin nasal ointment, and one patient complained of skin
tightness after using the Triclosan body wash.
Additional evidence that tea tree oil warrants further
consideration for MRSA decolonisation came from a larger study
in which 236 MRSA-positive patients were randomly assigned to
a standard treatment or tea tree oil treatment regimen26. The
standard treatment was a 4% chlorhexidine gluconate soap
applied all over the body at least once a day and 2% mupirocin
nasal ointment applied to the anterior nares three times a day,
combined with 1% silver sulfadiazine cream applied to skin
lesions, leg ulcers and wounds once a day. A 5% tea tree oil soap
and a 10% tea tree oil cream for anterior nares and skin lesions,
leg ulcers and wounds comprised the tea tree oil regimen. The
application frequency was the same as for the standard treatment
regimen and both regimens were used for 5 days. Swabs to test
for clearance were taken
2
days and 14 days after treatment
completion in 224 patients and the outcomes
in
these patients
were evaluated. While mupirocin was significantly better than
tea tree oil at eradicating nasal carriage, tea tree oil was
significantly better for skin sites. Overall, there was no
significant difference in the treatment regimens and no adverse
effects were reported in either treatment group.
Sporadic reports of the successful treatment of MRSA infections
by products containing tea tree oil have also appeared in the
literature. A mixture of plant extracts, including tea tree oil, was
used in the treatment of previously intractable MRSA
o~teomyelitis~~ with apparent success.
The formulation issues mentioned previously hold particular
relevance for the future clinical evaluation of tea tree oil
products. We have recently assessed the antibacterial activity of
tea tree oil and tea tree oil products using the EN 1276 and EN
12054 European suspension test methods4. The tea tree oil
products evaluated were a hygienic skin wash (HSW) and an
alcoholic hygienic skin wash (AHSW), both containing 5% tea
tree oil, and an alcoholic hand rub (AHR) containing 3% tea tree
oil. These formulations were assessed in perfect conditions using
the EN 12054 test, and in perfect conditions as well as in the
presence of interfering substances with the EN 1276 test, against
5'.
aureus, Acinefobacfer baumannii, Escherichia coli
and
Pseudomonas
aeruginosa.
With the EN 1276 test, the AHR achieved a 25 loglo reduction
against all the test organisms within
1
minute contact time. The
AHSW achieved this reduction with
A. baumannii
after
1
minute
contact time and against the remaining test organisms after 5
minute contact time. Using the
EN
12054 test, after
1
minute
contact time, 5% tea tree oil in 0.001% Tween 80 and the AHSW
achieved a reduction in
E.
coli
and
P. aeruginosa
concentrations in
excess of 4 loglo, while the AHR achieved this reduction against
all of the test organisms. In comparison, the HSW generally
required longer contact times to achieve smaller reductions in
test organism concentrations.
Oil concentrations and products that passed the European
suspension test guidelines were subsequently evaluated
in vivo
using the European handwashing method (EN 1499) as well as
ex
vivo
using freshly excised human skin samplesz8. Data from both
the
in vivo
and
ex vivo
methods indicated that 5% tea tree oil in
0.001% Tween 80 and the AHSW were significantly more active
than the non-medicated soft soap control after
1
minute of
handwashing or rubbing.
Safety
and toxicity
Just as clinical data to support the use of tea tree oil and tea tree
oil products in the management of MRSA colonisation and
infection are scarce, so too are safety and toxicity data for the oil.
While the anecdotal data from 80 years of use suggest that the
topical application of tea tree oil is safe, this is not a substitute for
empirical safety data. Some formal toxicity studies have been
conducted" but more are required. Most published reports of
adverse reactions discuss irritant and allergic skin reactions to the
oil
",
although cases of poisoning in children 31~3%nd adults
3"35
have occurred. Since tea tree oil is toxic if ingested and should
only be used topically, formal studies of its acute and chronic
effects on skin remain a priority.
Conclusions
Despite these limitations, the data from
in vitro
and
in vivo
work
reported to date provide a strong impetus for comprehensively
assessing the efficacy of tea tree oil in the management of MRSA
colonisation and/or infection. However, the question of who
would fund and conduct the required studies is a vexed one.
The fact that tea tree oil may be efficacious in the management of
MRSA but may not be validated due to a lack of financial support
highlights a critical issue in the future evaluation of many
complementary and alternative medicines. Unless novel
strategies that foster the rigorous evaluation of complementary
and alternative medicines and allow investors to reap the
commercial benefits of such work or substantial non-commercial
funding sources become available, complementary and
alternative medicines will remain largely uninvestigated.
Vol10 Issue
1
March 2005
Australian Infection Control
Some initiatives to address this dilemma have begun. In 1992,
the National Institutes of Health in the USA created an Office of
Alternative Medicine and provided it with a budget of US$2
million. This agency has since become the National Center for
Complementary and Alternative Medicine and has an operating
budget in 2005 of US$123 million. In 1999, the Therapeutic
Goods Administration in Australia established an Office of
Complementary Medicines; however, it has no budget for
research.
Ultimately, given the right circumstances, sufficient information
will be available to resolve the validity of the claims made for tea
tree oil. Whatever the outcome of current and future work, the
whole process will hopefully broaden our outlook and serve as a
template for the investigation of other complementary and
alternative medicines.
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Vol 10 Issue 1 March 2005
... Tea Tree Oil (TTO, Tea tree oil) is an essential oil obtained by steam distillation from the leaves of Melaleuca alternifolia (Myrtaceae) that grows naturally in Australia. Studies have shown that tea tree oil has a broad-spectrum antimicrobial activity with its high terpinen-4-ol content (Carson et. al, 2005). In Turkey, as in Europe and North America it has also begun to be used in various cosmetic preparations and care products. In recent years, tea tree oil has been described as a safe antiseptic, more preferred due to its natural origin. TTO is regarded as an ideal disinfectant for topical use due to its antimicrobial effect against a wi ...
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The increasing need of natural antimicrobial agents has started a new field of investigation due to the global diseases. Synthetic antimicrobial agents are found to be causing skin problems and other toxic effects in long term. Therefore, antimicrobial activity of three natural extracts tea tree oil, tree moss extract, oakmoss extract and organic o-phenylphenol were evaluated in the study. These agents were added to a bar soap formulation and tested for antimicrobial activity EN 1276 standard method. The agents were added to five bar soap formulation as i) bar soap base; ii) bar soap base and tea tree oil; iii) bar soap base, tea tree oil, tree moss extract and oakmoss extract; iv) bar soap base, and o-phenylphenol; v) bar soap base, tea tree oil, tree moss extract, oakmoss extract and o-phenylphenol were prepared. As a result, in formulation (i) bar soap could not only pass the antibacterial test. The maximum antimicrobial activity was seen in formulation (v).
... Tea tree (Melaleuca alternifolia) oil (TTO) is known since long for many remedial uses and has been claimed as a potential candidate to replace antibiotics particularly in topical applications (Carson et al., 2006). Early studies on the antimicrobial activity of TTO claimed that TTO to be more active against antibiotic-resistant bacteria (Carson et al., 2005). Furthermore, it is added as an active constituent in many topical formulations used for the treatment of cutaneous infections for controlling dandruff, acne, lice, herpes and other skin infections (Pazyar et al., 2013). ...
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