Otomycosis is fungal infection of the external auditory canal.
The incidence of otomycosis is not known but it is more common in hot climates and in those who partake 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 10% 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. An American study found that the incidence peaked during the summer months.
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. Eczema is another predisposing factor.
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. Results should be treated cautiously as contamination is common. Taking the swab from the medial aspect of the ear reduces this risk.
Otomycosis is a chronic recurring mycosis. The ear canal should be cleared of debris and discharge, as these lower the pH and reduce the activity of aminoglycoside ear drops. See separate Otitis Externa and Painful, Discharging Ears article. 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.
Burow's solution or 5% aluminum acetate solution should be used to reduce the swelling and remove the debris.
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. Eradication is more difficult in the presence of a mastoid cavity. Frequent cleaning with a cotton bud prolongs the condition. Persistent exposure to excessive moisture and delay in receiving appropriate medical or surgical treatment can prolong the recovery period.
Further reading and references
Herasym K, Bonaparte JP, Kilty S; A comparison of Locacorten-Vioform and clotrimazole in otomycosis: A systematic review and one-way meta-analysis. Laryngoscope. 2016 Jun126(6):1411-9. doi: 10.1002/lary.25761. Epub 2015 Nov 24.
Otitis Externa; DermNet NZ
Satish H et al; A Clinical Study of Otomycosis, IOSR Journal of Dental and Medical Sciences, 2279-0861.Volume 5, Issue 2 (Mar.- Apr. 2013).
Piercefield EW, Collier SA, Hlavsa MC, Beach MJ.; Estimated burden of acute otitis externa - United States, 2003--2007. MMWR Morb Mortal Wkly Rep. 2011 May 2060(19):605-9.
Kujundzic M, Braut T, Manestar D, et al; Water related otitis externa. Coll Antropol. 2012 Sep36(3):893-7.
Ho T, Vrabec JT, Yoo D, et al; Otomycosis: clinical features and treatment implications. Otolaryngol Head Neck Surg. 2006 Nov135(5):787-91.
Celebi Erdivanli O, Kazikdas KC, Ozergin Coskun Z, et al; Skin prick test reactivity in patients with chronic eczematous external otitis. Clin Exp Otorhinolaryngol. 2011 Dec4(4):174-6. doi: 10.3342/ceo.2011.4.4.174. Epub 2011 Dec 15.
Abou-Halawa AS, Khan MA, Alrobaee AA, et al; Otomycosis with Perforated Tympanic Membrane: Self medication with Topical Antifungal Solution versus Medicated Ear Wick. Int J Health Sci (Qassim). 2012 Jan6(1):73-7.
Latha R, Sasikala R, Muruganandam N; Chronic otomycosis due to malassezia spp. J Glob Infect Dis. 2010 May2(2):189-90. doi: 10.4103/0974-777X.62875.
Otitis externa; NICE CKS, July 2015 (UK access only)
Vennewald I, Klemm E; Otomycosis: Diagnosis and treatment. Clin Dermatol. 2010 Mar 428(2):202-11. doi: 10.1016/j.clindermatol.2009.12.003.
Jinnouchi O, Kuwahara T, Ishida S, et al; Anti-microbial and therapeutic effects of modified Burow's solution on refractory otorrhea. Auris Nasus Larynx. 2012 Aug39(4):374-7. doi: 10.1016/j.anl.2011.07.007. Epub 2011 Aug 20.
Viswanatha B, Sumatha D, Vijayashree MS; Otomycosis in immunocompetent and immunocompromised patients: comparative study and literature review. Ear Nose Throat J. 2012 Mar91(3):114-21.
Afolabi AO, Kodiya AM, Bakari A, et al; Attitude of self ear cleaning in black Africans: any benefit? East Afr J Public Health. 2009 Apr6(1):43-6.