Tea oil (TTO) is typically linked with skin

Tea tree oil, microbes, Propionibacterium acnes, skin,
Melaleuca
Alternifolia, antibiotics,
methicillin resistant Staphylococcus
aureus, antimicrobial

Abstract

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Regardless of developments in current
skills and knowledge, the healthcare industry is continually burdened with the dread
of microbial infections. Misusing antibiotics has moreover intensified this struggle,
producing a growth of antibiotic-resistant pathogens. Attempts to acquire novel
procedures for regulating microbial infections are very vital. Therefore , essential
oils such as tea tree oil have arose as new, feasible, and harmless choices for
the treatment, or abolition of these microbes. Tea tree oil components are talked
about in terms of current usages and upcoming capability as antimicrobials.
They have existed for thousands of years and previously to any contemporary
drugs which are now around. This review attempts to offer an explanation of by
what means tea tree essential oil can used be while being harmless and how they
should be used in the future to prevent and treat microbial infections.

INTRODUCTION

 

Tea tree oil is a prevalent essential oil used typically for
its potent antimicrobial possesions. It is volatile as an essential oil, and it
is obtained from an Australian plant called Melaleuca
alternifolia. It is extensively used to handle a number of conditions. Tea tree oil (TTO) is typically linked
with skin complaints such as acne, which is caused by a microbe recognized as Propionibacterium acnes. Antibiotics are
usually prescribed to handle this condition though there are currently antibiotic
resistant strains present (Coates et al. 2002).

 

Brief history. Tea Tree Oil first became known to the western world in around
1732. It was discovered by Captain James Cook when he reached Australia. He discovered
a hot and stimulating tea from the leaves of the Melaleuca Alternifolia tree. It was from this that the plant became
known as “tea tree”. The indigenous Australians at that point in time used it
to heal skin illnesses and injuries. When he understood this he returned with a
sample of the herb and had a medic inspect it for its healing possessions. The
doctor confirmed that it had an influential antiseptic trait. Shortly hereafter,
the use of TTO expanded, and it is now well-known worldwide as a non-synthetic antimicrobial
(Halcon et al. 2003).Australia is the only country where Melaleuca Alternifolia breeds so it must be transferred to various countries.

 

Chemical components.Tea tree oil is made up of many different biochemical constituents
that give it its antibacterial powers. The four main chemical components of tea
tree oil would be as follows; Terpinen-4-ol, ?-Terpinene, ?-Terpinene and Terpinolene
(see table 1).

 

Table 1. Approximate
percentages present of various biochemical components of TTO

 

Chemical constituent

Amount present(approx.)

Terpinen-4-ol

42%

?-Terpinene

10%

?-Terpinene

 5%

Terpinolene

 1.5%

 

The rest is made up of many different components which are
present in smaller amounts. Some other components are ; ?-Terpineol, ?-Pinene, Limonene
and ?-Cymene. There remain about 98 different components which can be present
in tea tree essential oil. The strengths of these components can vary in each
individual oil. However there stands to be certain standards put in position by
the Australian and International Standards Organizations to ensure value of the
oil i.e. a lowest and uppermost potency range for each constituent (Halcon et
al.2003). Tea tree oil can come in six different biochemical mixtures. There is
a terpinen-4-ol type which is produced on an industrial scale, a terpinolene
type, and four 1, 8-cineole types.

 

As was stated beforehand, persons worldwide are aware of
the antimicrobial effects of tea tree oil. In current decades natural and
alternative remedies are becoming more and more popular. This review accumulates
present developments in the recognition of the antimicrobial power of TTO and
its components, as well as scientific efficacy. Exact ways of antimicrobial
action are revised and analysed, mainly with regards to skin bacteria to see if
it could be used to replace traditional treatments of antibiotics and harsh
chemicals.

 

MICROBES

 

TTO shows antimicrobial action against a great range of
Gram-positive and Gram-negative bacteria, yeasts and fungi (Kulik et al.2000). However
it usually is more active to
Gram-positive than to Gram-negative microorganisms. The microorganisms that
will be concentrated on in this review are two gram positive microbes that target
the skin, Propionibacterium acnes and
methicillin resistant Staphylococcus aureus (MRSA) .We will similarly look at the fungus athlete’s foot.

 

Propionibacterium acnes. Tea-tree oil is a popular constituent of skin
preparations, and a number of its suggested usages indicate an anti-microbial
effect (Drury 1991). Tea-tree oil is recommended for the treatment of acne
vulgaris. A study comparing a tea-tree oil gel to benzoyl peroxide lotion
demonstrated the efficiency of the oil intended to treat the disorder (Bassett
et al. 1990). Propionibacterium acnes
and coagulase-negative staphylococci have been implicated in the pathogenesis of
acne vulgaris (Shanson 1989), and it is possible that the oil works by
eradicating these microorganisms from acne wounds. Propionibacterium acnes (P.acnes)
settle on the skin and hair follicles. They are oxygen-tolerant, anaerobic
bacteria that prefer to grow in low oxygen environments. They can develop sticky
lumps known as biofilms that help them to attach to surfaces and regulate their
environment (http://thescienceofacne.com/what-is-propionibacterium-acnes/). In
many situations, bacterial biofilms have been proven to add to long term
infections, and could help with the perseverance of P. acnes infection in some individuals. Because they are gram
positive microbes they have bulky cell walls that aid with defending them from
their surroundings. Still these thick cell walls let hydrophobic particles pierce
the cells without any difficulty and move through the cell wall and inside to the
cytoplasm. Phenolic compounds work this way and they are present in TTO, showing
antimicrobial action against Gram-positive bacteria such as P.acnes (Nazzaro et al. 2013). There are
plenty of additional gram-positive bacteria that create infections, such as
MRSA.

 

Methicillin resistant Staphylococcus aureus (MRSA). MRSA is a major cause of hospital
infections and is becoming increasingly difficult to combat as is it becoming resistant
to all current classes of antibiotics. About 30% of burn wounds become
colonized by MRSA in infirmaries. Alternative treatments are being sought for
the treatment of MRSA and essential oils are of specific interest. TTO is
proven to be effective in treating this antibiotic resistant strain of Staphylococcus; however there are
concerns over its toxicity. Even though essential oils are well known for being
antimicrobial, they are very seldom used by medical professionals. This is
mainly because of lack of scientific evidence regarding efficacy. Additionally
common medical care is extremely extensively accessible. Edwards-Jones et al. 2004
conducted a study trying to prove the efficacy of essential oils as
antimicrobial agents. The five oils used in the experiment that was carried out
were tea tree, lavender, geranium, patchouli and citricidal. TTO had the maximum
clearing zone when placed in direct contact with two different strains of Staphylococcus aureus. One of these was the
methicillin resilient strain. Essential oils obviously work, so why aren’t they
being used to treat these bacteria? There is great potential for the use of essential
oils as natural antibiotics to control infections, especially infections of the
skin and to control antibiotic resistant strains of bacteria. If there is no new
research done into discovering more antibiotics, by the year 2050 a person will
decease every three seconds from a bacterial disease (WHO). Because no new antibiotics
are being exposed it is time to move toward natural replacements and for money
to be put into researching essential oils in more detail. As well as being
antibacterial, TTO is also known for its antifungal properties.

 

Athlete’s foot. TTO is well recognized as being
effective in controlling the fungi that cause athletes foot. The fungus is known as Tinea pedis. It is often found in
people whose feet have come to be really moist from perspiration while enclosed
in tightfitting shoes. It is infectious and can be dispersed through infected floors,
towels or clothing. In a 1972 study done on various foot problems, Dr. Walker
used tea tree oil in three different formulas to try combating these problems. To
start was unmixed oil, secondly was a mixture of 40% oil with 10% isopropyl
alcohol. This was known as Melasol. Third was 8% oil with lanolin and
chlorophyll and this was in ointment form. 60 people took part in the
experiment. 40 took Melasol, 20 used the ointment and 8 applied the unmixed oil.
The medical care changed from three weeks to four years. Of 68 patients, 58 got
alleviation from their foot ailments over a time frame of 6 years. There are
four if not more various fungal diseases associated with athlete’s foot and
each of these display sensitivity to TTO.

Conventional treatments for fungal disease of the nails include;
debridement which is removing alien materials and impaired tissue from the nail,
and also there are topical treatments. This review evaluated the effectiveness of
topical treatments of 1% clotrimazole solution in comparison with 100% TTO for treating
of Tinea unguium which is a fungal
infection of the toenail. In a 6 month
double-blind, multicentre, randomised, controlled trial of 117 people with
a Tinea unguium
infection, patients got twice-daily
treatments of either 1% clotrimazole (CL) solution, which is topical antifungal
drug medication, or 100% (TTO). The fact the trial was double blind meant that
neither faction knew what the therapy that they were getting was. This helps to
remove any bias. The fact it remained a randomised trial ensured there was no
selection prejudices from the people who ran the trial.

Debridement and clinical evaluation were carried out at 0,
1, 3 and 6 months. Samples were taken at 0 and 6 months. After 6 months, the both
groups were associated based on culture cure (CL=11%, TTO=18%). Three months on,
almost half of both factions stated that they had persistent positive
development. The conclusion was, even though all ongoing treatments have high reoccurring
percentages, using a topical application along with debridement is a good
treatment to start with. Topical treatment, with regards to the previous two
concoctions, provides benefit in how the nail looks and any symptoms associated
with it, whereas oral treatment has the limitation of cost and likely negative
consequences. This experiment supported the requirement to use a strong (in
this case 100%) concentration of TTO to achieve improved short-term and
long-term efficiency. In children and people with sensitive skin, a 70%
solution may be superior.

 

EVIDENCE

 

In Vitro

 

There are a few ways in which TTO could be tested in
vitro. These include dilution, disk diffusion and agar well diffusion. We are
now going to look at different ways the antimicrobial effects of TTO have been
tested and the evidence they have provided.

 

Dilution. A study done by Walton et al in
2004 attempted to show the in vitro sensitivity of Sarcoptes scabiei var hominis to Terpinen-4-ol. The experiment went
as follows. The parts of TTO known as; terpinen-4-ol, terpineol, and 1,8-cineole
were utilized in vitro at concentrations equal to those in 5% TTO.Terpinen-4-ol
makes up 42% of TTO and was utilized at a concentration of 2.1%, terpineol makes
up 3% of TTO and was utilized at a concentration of 0.15%, and 1,8- cineole makes
up 2% of TTO and was utilized at a concentration of 0.1%.Also, mites were shown
to all 3 parts of TTO in a combined mix and to 5% TTO directly . An ivermectin
solution of 100 µg/g was also used for comparison along with Emulsifying
Ointment. The 5% TTO
and active component terpinen-4-ol were effective in reducing mite existence. Exact
applicable dissimilarity’s in mite survival graphs were noticed for 5% TTO,
terpinen-4-ol, and ivermectin compared to the control which was Emulsifying
Ointment. Change was seen in survival rates amongst each part of TTO. 85% of the
mites had deceased after 1 hour when shown to 2.1% terpinen-4-ol. Contrary to
this, almost 40% and 60% of mites had not deceased following 16 hours of
exposure to 0.15% terpineol and 0.1% 1,8-cineole. It was interesting to see
that 60% of mites had deceased after 1 hour of exposure to 5% TTO. There is
currently no vaccine for scabies and the growth of new medicines is scarce. The
rise of medicine defiant scabies is a serious issue for the health of many communities.
Examining scabies mite medications response to various stimuli can help recognize
a more practical use of accessible medications and medication combinations to help
decrease the development of defiance. The information showed in this appraisal shows
that TTO might be an active agent for the curing of scabies, as shown by the quick
in vitro killing time seen.

 

Kirby Bauer method (disk diffusion). Kirby-Bauer disk diffusion antibiotic
sensitivity analysis makes use of antibiotic-containing disks to examine whether
specific microorganisms are vulnerable to particular antibiotics. In this circumstance
the disks would contain TTO instead of an antibiotic. Initially, an
unadulterated culture of bacteria is isolated from the patient. After this, an
acknowledged quantity of bacteria is developed overnight on agar plates in the company
of a slim disc that comprises a recognized quantity of a suitable antibiotic
(TTO). If the microorganisms are vulnerable to the specific antibiotic, a zone of
clear media where microorganisms are unable to reproduce frames the disc, which
is recognized as the region of inhibition. A greater region of inhibition
around an antibiotic-comprising discus shows that the microorganisms are additionally
sensitive to the antibiotic in that specific disk. According to an analysis carried
out by Carson et al. 1995, all 66 isolates of Staphylococcus aureus tested were
susceptible to TTO in disc diffusion methods. Of the isolates examined, 64 were
MRSA and 33 were mupirocin-resistant. The smallest inhibitory strength and the
smallest bactericidal strength for 60 isolates were 0-25% and 0-50%,
correspondingly. Similar effects were gotten by co-workers using similar means.
These in-vitro outcomes propose that tea tree oil could be beneficial in the handling
of MRSA.

 

Agar Well diffusion. Classically,
an antibiotic is smeared on a well that is cut into the agar. Therefore, the
antibiotic will incline to transfer from this area of greater concentration to
the nearby area of lesser antibiotic concentration. The more antibiotic
material present in the well, the larger the zone of diffusion will be. This dispersal
is the foundation of the agar diffusion assay developed in 1944. A microbial suspension
is applied on the exterior of the agar. Next, antibiotic is smeared on a sum of
wells in the plate. There may be various strengths of a solitary antibiotic or
a sum of various antibiotics. After a period of time to allow for progression of
the microorganisms, the agar is then inspected. If microbial development is up
to the top of antibiotic comprising well, then the microbial strain is thought to
be resilient to the antibiotic. If a clearing around the antibiotic well is
present, then the microorganisms have been unfavourably affected by the
antibiotic. The scope of the inhibition region can be calculated and compared
to standard criteria, in order to govern whether the microbial strain is susceptible
to the antibiotic. Thomsen et al. 2011 conducted an analysis to examine the
antimicrobial action of a variety of commercially obtainable TTO merchandise.
One technique used was the agar well diffusion assay. The region of clearance
dimensions varied from 0 to 49.8 mm, with the additionally sticky and
lipophilic merchandises creating the smallest regions. Assumptions taken from
the study were that in general, the commercially obtainable sterile TTO
products presented antimicrobial activity that was equivalent to, or greater
than the non-formulated TTO control.

 

 

In Vivo

 

In vivo testing
refers to testing in the living organism. For example, an experiment that is
done in vivo is done in the body of a living organism as opposed to in a
laboratory method that does not use the living organism as the host of the
test. In vivo is the opposite of in vitro and can be either animal or human.
Human in vivo testing is known as clinical trials.

 

Animal. Mondello
et al. 2006 carried out an in vivo investigation to determine the activity of terpinen-4-ol,
against human pathogenic Candida
species. Oophorectomized, rats under estrogenic treatment were used for
experimental vaginal infection with various strains of C. albicans that were resistant to forms of antifungal treatment.
The result of this rat vaginal model was that terpinen-4-ol was as active as
TTO in accelerating clearance from the vagina of all Candida strains examined.
This is the first in vivo demonstration that proves that terpinen-4-ol could
control C. albicans vaginal
infections. The purified compound holds promise for the treatment of vaginal
candidiasis, and particularly the azole-resistant forms.

 

Human. The
clinical efficacy of TTO is under the subject of investigation. Early clinical
studies attempting to characterize the clinical efficacy of TTO are not
considered scientifically valid by today’s standards. Therefore more in vivo
trials need to be carried out to prove the efficacy of the oil and how it can
be as efficient if not more successful and with less side effects than most
conventional treatments.

One of the first rigorous clinical studies assessed the
efficacy of 5% TTO in the treatment of acne by comparing it to 5% benzoyl
peroxide (BP) (Carson et al.2006).The study found that both treatments reduced
the numbers of inflamed lesions, although BP performed significantly better
than TTO. The BP group showed significantly less oiliness than the TTO group, however
the TTO group showed significantly less scaling, itching, and dryness.
Significantly fewer overall side effects were reported by the TTO group (27 of
61 patients) than by the BP group (50 of 63 patients). This study included 124
patients suffering from mild to moderate acne and was a randomized controlled trial
(RCT). As TTO has such a distinctive odour the patients could not be blinded,
however the investigators were instead blinded. The trial lasted three months.

Satchell et al. 2002 carried out a
trial using 5% TTO shampoo to help combat dandruff. Dandruff can be caused by yeast
like fungus known as malassezia and as previously discussed TTO works as an
antifungal. A RCT was carried out which contained 126 people with mild to
moderate dandruff. Once again it was the investigator that was blinded due to
its distinctive odour. 63 people used the 5% TTO shampoo and 62 used a placebo
shampoo. The shampoo was to be used daily for four weeks. At the end of the
four weeks, 41.2% of the TTO group had a completely dandruff free scalp in comparison
with the placebo group that only 11.2% achieved results. As well as having
better results, the TTO group reported fewer adverse side effects. Only 5% of
the TTO group report cases of burning, stinging or itching compared to 13 % in
the placebo group.