Oropharyngeal candidiasis (OPC) is the most common opportunistic infection observed in patients with HIV/AIDS [1,2]. Approximately 80–90% of patients with AIDS will develop OPC at some stage [3,4]. Candida albicans accounts for the overwhelming majority of cases of oral thrush , which impairs the quality of life and may result in a reduction in fluid or food intake. There are several antifungals available to treat oral candida infection including nystatin, amphotericin B, clotrimazole, miconazole, itraconazole, fluconazole, and ketoconazole. Several of these are systemic and there is always a potential for drug interactions. The incidence of fluconazole-refractory OPC is becoming increasingly more common and frequently may emerge during therapy [5,6]. Intravenous amphotericin B has been effective therapy for refractory OPC, but this approach is inconvenient, expensive and associated with significant morbidity.
Melaleuca oral solution (Breath-Away, Melaleuca, Inc., Idaho Falls, Idaho, USA) is a non-prescription mouthwash preparation with documented in vitro activity against yeast and fungi, which is derived from Melaleuca alternafolia, an Australian tea leaf [7,8]. This small single center prospective study assessed the efficacy and safety of melaleuca oral solution in AIDS patients with fluconazole-refractory OPC.
Patient and methods
Men and women between the ages of 18 and 65 years were eligible for study entry if they were HIV-positive and met the criteria for the diagnosis of OPC of either the pseudomembranous or erythematous (atrophic) variety. The two entry criteria were as follows: (i) the presence of OPC characterized by creamy, white, curd-like patches, removable by scraping, or typical erythematous lesions on the oral mucosal surfaces, and a KOH test consistent with Candida spp. and subsequently confirmed by fungal culture; and (ii) all patients must have failed to respond to a minimum of 14 days of ≥ 400 mg daily fluconazole within 14 days of study entry.
A single center, open-label clinical trial was conducted to evaluate melaleuca oral solution four times daily for the treatment of fluconazole-refractory OPC in 13 AIDS patients. Patients were treated with a 15 ml mouth ‘swish and expel’ (see below) of melaleuca oral solution four times daily for 2 weeks, and an additional 2 weeks for patients who showed clinical improvement but who had not demonstrated a complete clinical response at the end of the initial 2 weeks of therapy. The clinical study protocol was approved by the Institutional Review Board at our institution and each patient provided written informed consent prior to study participation.
Drug dosing and administration
Melaleuca oral solution was provided in 118 ml bottles. Patients were instructed to take 15 ml of the solution four times daily for 14 days. The solution was to be swished in the mouth for 30–60 sec and then expelled, with no rinsing afterwards for at least 30 min.
Efficacy and evaluations
On enrollment at the first visit, a complete and history and physical examination was performed. Evaluation of signs and symptoms was carried out and recorded. The severity of soreness, burning and erythema were scored on a 0–3 scale as follows: absent, 0; mild, 1; moderate, 2; severe, 3. The extent of the lesions were scored as follows: absent, 0; single, localized, 1; multiple, localized, 2; extensive or confluent, 3. All affected sites were recorded diagrammatically. The severity score was the total score of soreness and burning plus erythema plus the extent of the lesions.
Clinical evaluations were also performed on days 7 and 14, and also on days 28 and 42 of follow-up. Assessments of signs and symptoms of OPC were conducted by an evaluator (J.A.V.), and grading was performed. OPC was considered to be ‘cured’ when clearance of all signs and symptoms occurred, ‘improved’ when minimal signs and symptoms with minimal residual visible lesions of OPC were observed, ‘unchanged’ when there was no change in signs and symptoms or the need for continued treatment, and ‘deteriorated’ when there was worsening or increasing signs and symptoms. At end of therapy an assessment of ‘cured’ or ‘improved’ was considered a clinical response.
Mycological assessments included a KOH test, fungal culture on Sabouraud dextrose agar, yeast quantification, and in vitro susceptibility studies. Yeast quantification was performed using c.f.u./ml of Candida spp. recovered. The test was performed using a 15 sec mouthwash procedure with 15 ml normal saline, which was swished in the mouth and expelled into a 50 ml tube. Afterwards, 100 µl of the suspension was plated on Sabouraud dextrose plates and colonies counted. The mouthwash procedure was performed before breakfast and before taking any test medication the day of the follow-up. Mycological cure was defined as below 20 c.f.u./ml on mouthwash quantification studies. Negative culture was defined as no growth on culture plate. Yeast isolates were identified using germ tube formation, chlamydospore formation on cornmeal agar, and the API 20C method (Biomerieux, Vitek, Inc., Hazelwood, Missouri, USA).
In vitro susceptibility studies were performed using fluconazole, ketoconazole, itraconazole and amphotericin B for each initial isolate from all patients enrolled into the study. The minimal inhibitory concentrations (MIC) of all antifungal agents for all isolates were determined in accordance with the National Committee for Clinical Laboratory Standards M27-P protocol by a broth microdilution method for all antifungals . A standard inoculum was diluted to a final concentration of 0.5–2.5 × 103 c.f.u./well in microtiter plates containing RPMI-1640 medium. The final concentrations of fluconazole were 0.16–80 µg/ml, those of itraconazole and ketoconazole were 0.05–12.5 µg/ml, and those of amphotericin B were 0.006–3.1 µg/ml. An overall response was defined as a clinical response plus a mycological response.
Assessments for adverse events were performed during visits, at the end of therapy, and at follow-up. Physical examination was performed at the end of the treatment period. Clinical laboratory tests, hematology, blood chemistry and urinalysis were performed at baseline and during treatment as clinically indicated.
Thirteen patients were enrolled in the study. One patient was enrolled but never returned for follow-up (patient 11). The 12 evaluable patients had a mean age of 33 years (range, 28–48 years), and all 12 were men, with a median CD4 cell count of 10 × 106/l; seven were black, five were Caucasian, and one was Hispanic. All patients had a history of at least one prior episode of OPC. In addition, 10 out of 13 patients had at least one AIDS-defining illness prior to fluconazole-refractory thrush. The most common events were Pneumocystis carinii pneumonia (six patients), Candida esophagitis (five patients), Mycobacterium tuberculosis infection (three patients), cytomegalovirus retinitis (one patient), and Kaposi's sarcoma (one patient). Baseline evaluations of patients are shown in Table 1.
The evaluation of clinical efficacy was based on an intention-to-treat analysis (Table 2). Clinical response to the melaleuca solution was observed in eight patients. Two patients were clinically cured and six were improved after 28 days of therapy. Four patients were unchanged after 28 days of therapy and one patient deteriorated by developing esophageal candidiasis. Thus, 16.7% of the patients were clinically cured and an additional 50% were clinically improved for an overall clinical response rate of 67% (eight out of 12). It is important to note that although the response rate at the end of 4 weeks was 67%, at the end of the initial 2-week follow-up period no patients were cured and six were still unchanged (Table 2). At the end of the study period (6 weeks), both of the patients who were cured remained relapse-free for at least 2 weeks after the last study dose.
All 13 patients who provided informed consent and were entered into the study had positive oral cultures for yeast on study entry. C. albicans was the only yeast recovered from the oral specimens. Table 1 shows the fungal colony counts at baseline and at the 4-week follow-up. Nine out of 12 patients had significant decreases in colony counts after 4 weeks of therapy with melaleuca.
In vitro susceptibilities of the C. albicans isolates revealed that all isolates had an MIC to fluconazole of > 20 µg/ml (range, 20–80 µg/ml), a 50% MIC (MIC50) of 40 µg/ml, and a 90% MIC (MIC90) of 80 µg/ml. The MIC50 of amphotericin B was 0.05 µg/ml (0.02−0.4 µg/ml). Itraconazole had an MIC50 of 0.4 µg/ml (range, 0.02−12.5 µg/ml), and ketoconazole had an MIC50 of 0.01 µg/ml (range, 0.01−0.05 µg/ml).
There were no serious adverse events. Evaluation for adverse events revealed that eight of the 12 patients noted mild-to-moderate oral burning when the solution came into contact with their oral mucosa. This complaint was primarily noted the first week of therapy and gradually decreased with improvement of OPC. No new laboratory abnormalities developed during the study period. However, a significant problem was noted with compliance. Four of the patients enrolled were non-adherent with the study regimen prescribed or did not attend their scheduled clinic visits.
There is a growing interest in the use of naturally occurring substances for the treatment of a variety of medical conditions. Melaleuca (tea tree oil) has been used as a natural topical antiseptic since the early part of this century [8,10]. It has also been used as an antiseptic agent in denture and mouth washes. Melaleuca oil has been previously analyzed by gas chromatography and a large number of its chemical constituents have been defined . In addition, melaleuca has been tested for its antibacterial and antifungal activity in vitro. Staphylococcus aureus and most of the Gram-negative bacteria tested were found to be susceptible using a modified broth microdilution method [10,12]. The antimicrobial activity of eight of the components of tea tree oil were also evaluated using disc diffusion and broth microdilution methods against C. albicans, Escherichia coli and S. aureus . These organisms were all found to be susceptible to melaleuca in these in vitro studies. In addition, Nenoff et al.  have recently completed a study investigating the in vitro activity of M. alternifolia oil against 26 strains of dermatophytes and 54 strains of yeast. Their results demonstrate that the melaleuca oil preparation used effectively inhibited growth of all clinical fungal isolates at concentrations of 0.5–0.44%. These concentrations are far lower than the 5–10% concentrations from many of the clinically available melaleuca preparations.
More recently, tea tree oil has been used in treatment trials for tinea pedis. A comparative study of topical clotrimazole versus M. alternifolia oil for the treatment of onychomycosis was recently published. The study was a double-blind, multicenter, randomized trial that enrolled 117 patients with distal subungual onychomycosis and followed them for 6 months for signs and symptoms of improvement. Improvement was noted in 55% of patients on clotrimazole and in 56% of patients on melaleuca . A second study published in 1992, however, gave conflicting results. In this study, use of tea tree oil was compared with 1% tolnaftate ointment or placebo creams in patients with tinea pedis. In this study, 85% of the patients on the tolnaftate arm had negative fungal cultures at the end of study, whereas 30% of the tea tree oil-treated patients, and 21% of the placebo-treated patients, had negative cultures .
To our knowledge, our study is the first to evaluate the treatment of fluconazole-refractory OPC in patients with advanced AIDS using melaleuca oral solution. The clinical outcome in this study population demonstrated a greater than 65% efficacy in this advanced, immunocompromised patient population. Only one patient deteriorated while on therapy when he developed esophageal candidiasis. However, this event has previously been reported with other forms of topical antifungal therapy such as nystatin, amphotericin B or clotrimazole, and is difficult to predict. Many patients with HIV infection are treated with topical antifungals for OPC. Similarly, treatment with topical antifungal agent therapy such as melaleuca is not intended to treat esophageal candidiasis, but to alleviate oral symptoms and improve the well-being of patients with fluconazole-refractory OPC.
We feel that the results of this pilot study are extremely promising and that further large, comparative multicenter studies using melaleuca oral solution are warranted. Moreover, M. alternafolia may become an alternative antifungal agent for the treatment of OPC in either the early or late stages of HIV infection.
The authors thank Melaleuca, Inc. (Idaho Falls, Idaho, USA) for providing the Breath-Away oral solution used in this study and Eileen Surma for the excellent secretarial support.
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