Abstract
Numerous studies have shown the promising antibacterial effects of Melaleuca alternifolia, or tea tree essential oil. The study detailed here replicates in humans a 2004 in vitro study that used a dressing model over Petri dishes to determine the antimicrobial effects of the fumes of tea tree essential oil. The current study used the same dressing model with patients who had wounds infected with Staphylococcus aureus. Ten participants volunteered for the quasi-experimental study, and four of the 10 were used as matched participants to compare wound healing times between conventional treatment alone and conventional treatment plus fumes of tea tree essential oil. The results demonstrated decreased healing time in all but one of the participants treated with tea tree oil. The differences between the matched participants were striking. The results of this small investigational study indicate that additional study is warranted.
Introduction
A
One area of interest for alternative treatment of S. aureus, as well as MRSA, is aromatherapy or the use of essential oils. Hundreds of essential oils are commercially available for use, many with known antibacterial properties. These oils contain numerous constituents that contribute to the characteristic odor and medicinal effects. The major chemical components that account for the antibacterial properties are primarily phenols and alcohols. The presence and quantity of the chemical components vary between oils and determine the therapeutic nature of the oil. 2 Although many essential oils are known for their antimicrobial properties, medical teams rarely use them. This is primarily due to lack of scientific evidence of their efficacy, concern for toxicity, and the reliance on conventional therapy. 3
A wealth of in vitro data now support the long-held belief that Melaleuca alternifolia (tea tree) essential oil has antimicrobial and anti-inflammatory properties. 4,5 Nelson tested a range of essential oils and extracts for their antibacterial properties using an in vitro dressing model to assess the antimicrobial action of the vapors. 6 Of the single oils used, only tea tree oil vapor produced any zones of inhibition, and this was noticeable only in one strain of Oxford Staphylococcus. The bacteriostatic and bacteriocidal activities of five essential oils against 15 strains of MRSA and five of vancomycin-resistant enterococcus were documented. Tea tree oil was the most potent of the five oils. These results are identical to those reported previously for strains isolated in both the United Kingdom and Australia.
The study detailed here replicates with humans the 2004 in vitro study conducted by Edwards-Jones et al., who used a dressing model over Petri dishes to determine the antimicrobial effects of the fumes of tea tree essential oils. 7 The current study used the same dressing model with matched participants who had wounds infected with S. aureus.
Research Questions
Null hypothesis
There will be no difference in the rate of wound healing of wounds infected with S. aureus with the use of conventional treatment versus treatment of wounds with the addition of tea tree vapors.
Questions
1. Do healing rates differ between wounds that are treated conventionally and those that are also treated with tea tree oil vapors?
2. Is there a correlation between an in vitro dressing model and an in vivo (in humans) scenario?
Materials and Methods
This study used a quasi-experimental design with experimental and control participants. Quantitative data included visual tracking of wound size in centimeters, as well as presence or absence of redness and induration. Qualitative data were collected in the form of patient comments. “Matched participants” is the preferred experimental design for this type of research with a limited number of participants.
Nursing staff from the Good Shepherd Medical Center (GSMC) Wound Clinic and the GSMC Rural Health Clinic in Marshall, Texas, as well as the Jefferson Life Center Clinic in Jefferson, Texas, were trained in the dressing model to use for the experimental and control participants.
Participants
The target population consisted of patients being treated for abscessed wounds that were diagnosed with S. aureus. During the 3-month timeframe, a convenience sample of 10 patients participated in this study (Table 1). Four of the participants were chosen for the matched group. The two pairs of participants were matched as closely as possible by age, gender, infectious vector, and number of days with infected wound (Table 2).
F, female; M, male; y, years; d, days.
Research instruments/tools
The tea tree and grapeseed oils used in this study were from the Elizabeth Van Buren Essential Oil Therapy, Santa Cruz, CA (
Procedures
The GSMC Ethics Committee acted as the institutional review board and oversaw the project. The participants gave permission to have their wounds treated with tea tree oil as described for the dressing model or conventional treatment. Written consent was obtained from all participants, and confidentiality was maintained.
Patch testing was prescribed with 4% tea tree oil mixed with pressed grapeseed oil as a carrier on a cotton ball, to be taped to the subject's inner forearm for 24 hours. Even though the oil would not be in contact with the skin and tea tree oil is commonly used neat (100%) on healthy skin, 8 it was considered prudent to perform patch testing with the participants. For the experimental group, six pipette drops (the approximate equivalent of two drops from a full-sized dropper) of full-strength tea tree oil were placed at the center of the bottom of the dressing: an abdominal pad, Telfa pad, or gauze. Wounds were measured and described as per clinic protocol by participating nurses. Dressings were changed every 3 days and oil reapplied for experimental participants with each dressing. Follow-up assessment of the wounds occurred at the clinics during the participants' regularly scheduled appointments.
The researcher worked closely with the participating physicians and the various clinic nursing staff to ensure they adhered to the protocol consistently so use of the dressing model on wound healing among the participants would be replicated. This also allowed the researcher to observe, track, and monitor the wounds. Medical records were made available to the researcher for compilation of data as described in the participant's consent form.
Results
Two sets of matched participants completed the research protocol (Table 2).
First matched-participant set
Control participant A: An 18-year-old man presented to the emergency department with a 2-day-old cutaneous abscess and cellulitis of the medial aspect of his right thigh. The abscess was incised and drained, which left an open wound 2–3 cm long. The wound was treated with 5–6 cm of plain packing, along with a prescription of azithromycin. The patient was next seen at the Rural Health Clinic 3 days later for repacking of the wound; he returned in another 3 days for further follow-up. At this time, 6 days after his initial ED visit, the size of his wound was unchanged; it was documented at 2–3 cm, and 4–5 cm of packing continued was used. One week after this last visit, this young man's wound was documented as “healing well,” with the wound size now at 1–2 cm with minimal discharge. One-quarter-inch plain packing was still necessary at this time. Fifteen days of treatment had elapsed.
Experimental participant A: A 15-year-old boy presented to the Jefferson Clinic with a 2-cm right upper buttock lesion with infection/abscess of 5 days' duration. Pus and blood were present. The wound was cultured as “heavy growth of staph aureus.” Although no packing was used, the tea tree protocol was used in a dry dressing to cover the wound. Twenty-four hours later, after having taken only two doses of antibiotics (clindamycin and trimethoprim-sulfamethoxazole), he returned to the clinic for follow-up; there was no sign of an abscess and no tenderness. The participant stated, “It's 100% better!”
Second matched-participant set
Control Participant B: A 38-year-old woman was seen at the Rural Health Clinic with an erythematous induration on the right calf from an insect bite that had occurred 4 days before her initial clinic visit. The patient had no drainage and no fever, but the 3-cm induration was warm to touch. She received an intramuscular injection of ampicillin-sulbactam and was prescribed trimethoprim-sulfamethoxazole for 10 days. Three days later she returned; the induration had developed a pustular head. The ensuing incision and drainage of pus and blood left a 2- to 3-cm wound that was then packed with 7 inches of one-quarter-inch iodoform packing and covered with 4×4 gauze. She was also prescribed amoxicillin-clavulanate. Her follow-up appointments included four more visits over the next 16 days, during which the area was flushed, cleaned with saline, and repacked with plain gauze and normal saline solution. The area remained indurated. On day 19 of treatment, the patient remarked, “ It feels like it should be healed quicker than it has.” At this time the wound was repacked with 2 inches of one-quarter-inch plain gauze and saline solution. The patient still reported soreness and tenderness.
Experimental participant B: A 26-year-old man developed a scalp abscess after a haircut. He presented 3 days later with a 2-cm fluctuant area with a 1-inch round area of alopecia. Incision and drainage of the area resulted in a 12-cm packing of one-quarter-inch iodoform gauze. A dry dressing with tea tree protocol was placed over this area. He returned 3 days later. The site was healing well, with no discharge or cellulitis and no induration. The 5-inch packing was replaced with another one-quarter-inch iodoform gauze, this time only 3 inches long. Again, tea tree oil was placed in the dry dressing. This patient returned only once more, 3 days later. The wound was healing well; the area was <1 cm and had no induration. The site was repacked with only 1 inch of plain gauze and saline solution; tea tree oil was again applied to the covered dressing. This patient made no other visits for repacking.
Additional participants
An additional six patients, all with abscesses and/or cellulitis diagnosed with S. aureus, were included in the data collection of this study. Only one patient showed no change at all with the use of tea tree oil. This patient was 70 years old and had multiple medical problems, such as diabetes and hypertension; the main issue was respiratory in nature. The five remaining participants showed healing in an average of 4.4 days of treatment with tea tree oil (Table 1).
Conclusions
Do healing rates differ between wounds that are not treated with tea tree oil vapors and those treated with tea tree oil vapors? From Tables 1 and 2, one can easily see the differences in healing rates between the control and experimental participants. The matched participants are the most remarkable, but all participants with tea tree oil except one showed accelerated healing times.
Is there a correlation of results from an in vitro model to an in vivo (in human participants) scenario? This small study demonstrates results similar to those of previous research: Experimental participant 1 saw almost immediate positive effects from the application of tea tree oil (within 24 hours). This concurs with the findings of Edwards-Jones et al. (2004), 7 who noted a significant decrease in S. aureus in the same timeframe—24 hours—with their Petri dishes.
Control participant 2, who initially received conventional treatment, was offered treatment with tea tree oil on day 19 of her clinic visits. She did not return for any more of her follow-up appointments. When she was reached by phone almost a month later, she remarked that on the evening of her last clinic visit, the packing had “fallen out.” After her bath, she replaced the original dressing on which “the smell-good stuff was still on it.” The next day, she removed the dressing, only to find the wound had “closed up.” She never again replaced the dressing. Her leg was no longer tender or sore, and for the first time in almost 3 weeks, she went to work without a dressing on her leg. The follow-up of this case study further reinforces the positive impact of tea tree on wound healing and points to the need for larger controlled studies.
Discussion
Tea tree essential oil does indeed appear to assist with the accelerated healing of abscessed wounds and cellulitis. Tea tree oil appears to be a safe complementary modality in the treatment of these common infections. In decreasing the healing time, the use of this oil can improve patient satisfaction and may also help with nonadherent populations, who may not always return for follow-up appointments. A large double-blinded study would go a long way to further convince the U.S. medical community of the benefits of essential oils on wound healing. Further study is warranted to observe the effects of tea tree oil with and without conventional antimicrobial pharmaceutical treatment for both S. aureus and MRSA.
Many commercial products, such as shampoos and lotions, purport to have tea tree oil as a part of the ingredients. No research has been done to determine whether a tolerance or toxicity can occur that might negatively affect the outcome of wound healing in a clinical setting. This would be an important aspect for future study.
An obvious limitation of this study is the small convenience sample. The 10 participants volunteered for the study, and it is not known whether the volunteers differed in some way from patients who did not volunteer.
Another limitation is that the Rural Health Clinic did not routinely culture all of the abscessed wounds presented to them. That additional cost for this mostly uninsured population was generally thought to be unjustified. As such, S. aureus could only be assumed as the offending microorganism, but it was not documented.
An additional limitation is that the type of antibiotics used differed between the matched participant pairs as well as the other six participants. The type of antibiotic used was not controlled for, nor were other variables, such as age or immune system function. Again, a larger study controlling for as many variables as possible is recommended.
Footnotes
Acknowledgments
We would like to thank Kay Jarrell, RN, FNP, from the Rural Health Clinic, who used the tea tree oil whenever possible. Sherby Holloway, PA, was instrumental in providing the control groups. Lottie Marsh, LVN, the Rural Health Clinic charge nurse, was helpful in allowing access to the facility. Trent Gale, RN, FNP, and Robin Gale, RN, PNP, both from the Jefferson Life Center Clinic, were also extremely excited to use tea tree oil in their practice. These were the primary health care providers who volunteered to be on the front lines with this project. We would like to mention the entire staff at the GSMC Wound Clinic from whence this project began. Katherine Balbuena, MD, was key in helping this project, and we are grateful for her enthusiasm and support. The Ethics Committee from GSMC Marshall, headed by Robert Palmer, MD, oversaw this project with much interest and gave official approval for this study. No funding was provided for this study.
Disclosure Statement
No competing financial conflicts exist.