Otomycosis is fungal infection of the external auditory canal.
- Add notes to any clinical page and create a reflective diary
- Automatically track and log every page you have viewed
- Print and export a summary to use in your appraisal
The incidence of otomycosis is not known but it is more common in hot climates and in those who indulge in aquatic sports. About 1 in 8 of otitis external infections is fungal in origin. 90% of fungal infections involve Aspergillus spp. and the rest Candida spp. The prevalence rate has been quoted as 9% of patients presenting with signs and symptoms of otitis externa. The fraction of otitis externa that is otomycosis may be higher in hot climates and much of the literature originates from tropical and subtropical countries. In the UK, the diagnosis of otitis externa is made most often in late summer when swimming is most common.
Factors that predispose to otitis externa include absence of cerumen, high humidity, increased temperature, and local trauma - usually from use of cotton swabs or hearing aids. Cerumen has a pH of 4 to 5 and so suppresses both bacterial and fungal growth. Aquatic sports, including swimming and surfing, are particularly associated because repeated exposure to water results in removal of cerumen and drying of the external auditory canal. There may be a history of previous invasive procedures on the ear. Other predisposing conditions include eczema, allergic rhinitis and asthma.
The typical presentation is with inflammation, pruritus, scaling and severe discomfort. The mycosis results in superficial epithelial exfoliation, masses of debris containing hyphae and suppuration. Pruritus is more marked than with other forms of ear infections and discharge is often a marked feature.
The initial presentation is similar to bacterial otitis externa but otomycosis is characterised by many long, white, filamentous hyphae growing from the skin surface. Suspicion of fungal infection may arise only when the condition fails to respond to antibiotics. Even if bacteria have been grown, there may be more than one aetiological agent. It is also possible that topical antibiotics have predisposed to the fungal infection.
An essential piece of history that may easily be missed is a holiday in an exotic place with surfing or SCUBA diving.
Swabs from infected ears should be examined for both bacteriology and mycology. Epithelial debris placed in 10% potassium hydroxide should reveal the presence of hyphae and, in some instances, the fruiting structures of the aetiological agent.
Otomycosis is a chronic recurring mycosis. The ear canal should be cleared of debris and discharge as this lowers the pH and reduces the activity of aminoglycoside ear drops (see separate article Otitis Externa and Painful, Discharging Ears). Suction can be used if available. Cleaning may be required several times a week. Analgesia is required. If there is an irritant or allergen it must be removed. Keep the ear dry and avoid scratching it with cotton wool buds. Avoid cotton wool plugs in the ear unless discharge is so profuse that it is required for cosmetic reasons. If used, keep them loose and change often.
Burrow's solution or 5% aluminum acetate solution should be used to reduce the swelling and remove the debris. An aqueous solution of 1% thymol in metacresyl acetate, or iodochlorhydroxyquin should be considered if drying the ear does not work satisfactorily.
Antifungal ear drops are of value. There is no consensus on treatment but evidence supports the use of topical ketoconazole. Clotrimazole and econazole drops are very effective but may be needed for 1 to 3 weeks. Clioquinol is both antibacterial and antifungal and may be used as ear drops with hydrocortisone in the formulation of Locorten-Vioform®.
Cleaning of the ear can represent a problem in the presence of a perforated eardrum and a specialist may need to be involved.
Once antifungal therapy is started there is usually good resolution in the immunologically competent. However, the risk of recurrence is high if the factors which caused the original infection are not corrected and the normal physiological environment of the external auditory canal remains disturbed. These include avoiding sudden manoeuvres in the external auditory canal (eg frequent cleaning with a cotton bud), taking care to avoid excessive moisture by not going in the water and receiving appropriate medical or surgical treatment for otitis externa.
Further reading & references
- Garry JP et al, Otitis Externa, Medscape, Feb 2010
- Ho T, Vrabec JT, Yoo D, et al; Otomycosis: clinical features and treatment implications. Otolaryngol Head Neck Surg. 2006 Nov;135(5):787-91.
- Rowlands S, Devalia H, Smith C, et al; Otitis externa in UK general practice: a survey using the UK General Practice Research Database. Br J Gen Pract. 2001 Jul;51(468):533-8.
- Kaur R, Mittal N, Kakkar M, et al; Otomycosis: a clinicomycologic study. Ear Nose Throat J. 2000 Aug;79(8):606-9.
- Jackman A, Ward R, April M, et al; Topical antibiotic induced otomycosis. Int J Pediatr Otorhinolaryngol. 2005 Jun;69(6):857-60. Epub 2005 Feb 26.
- Otitis externa, Clinical Knowledge Summaries (2007)
- Stern JC, Shah MK, Lucente FE; In vitro effectiveness of 13 agents in otomycosis and review of the literature. Laryngoscope. 1988 Nov;98(11):1173-7.
- Georgiev V; Opportunistic Infections: Treatment and Prophylaxis 2003
- Bassiouny A, Kamel T, Moawad MK, et al; Broad spectrum antifungal agents in otomycosis. J Laryngol Otol. 1986 Aug;100(8):867-73.
- Maher A, Bassiouny A, Moawad MK, et al; Otomycosis: an experimental evaluation of six antimycotic agents. J Laryngol Otol. 1982 Mar;96(3):205-13.
- Hueso Gutiérrez P, Jiménez Alvarez S, Gil-Carcedo Sañudo E et al; Presumption diagnosis: otomycosis. A 451 patient study Acta Otorrinolaringol Esp 2005; 56: 181-186
|Original Author: Dr Laurence Knott||Current Version: Dr Laurence Knott|
|Last Checked: 20/12/2010||Document ID: 1011 Version: 25||© EMIS|
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.