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Abstract
Objective: The purpose of this study was to determine the susceptibility of organisms causing otitis externa (OE) to the essential oil of Melaleuca alternifolia, or tea tree oil (TTO).
Methods: Fifty-seven swabs were taken from the ears of 52 patients with OE for culture and sensitivity. A broth microdilution method was used to determine the minimum inhibitory concentration (MIC) of TTO for each organism.
Results: In 51 per cent of the swabs taken, pathogenic organisms were cultured. Of these cultures 71 per cent, both bacteria and yeast, were susceptible to TTO 2 per cent or less. The only organism showing resistance to TTO was Pseudomonas aeruginosa; however 25 per cent of these bacteria were sensitive.
Conclusion: Tea tree oil may have a role to play in the treatment of OE. However, more work needs to be done to enhance the anti-pseudomonal effect and to assess ototoxicity.
Key words: Otitis Externa; Tea Tree Oil; Microbiology
Introduction
Otitis externa (OE) is an umbrella term for the condition of inflammation of the external auditory canal and pinna. It is one of the most common conditions seen in otolaryngologic practice, affecting 3 per cent to 10 per cent of the patient population.1 The disease is characterized by itching, tenderness and pain. Hearing loss and the sensation of aural fullness may develop as keratinous debris and soft tissue oedema combine to block the canal. Examination will frequently reveal the presence of erythema or oedema of the ear canal skin often accompanied by a purulent otorrhoea. The aetiology includes non-infective causes such as eczema and psoriasis, but more commonly it is the result of infection with pathogenic organisms, including bacteria, fungi and yeast.
Treatment of an active infection typically includes the use of topical antibiotic drops and, if necessary, the cleansing of debris from the external auditory canal. Separate topical preparations are available for fungal and bacterial infections. Many of these preparations contain agents that are known to be ototoxic, although their use in the presence of active infection is considered safe. Another common problem with topical treatments is the development of hypersensitivity to the antibiotic, the steroid, or the preservatives contained in the product. A study of 142 patients with chronic OE has revealed positive allergy to one...