Otomycosis is a fungal infection of the external ear extending to the adjoining structures like middle ear and open mastoid cavity. The fungi have been implicated overall in ~9% of cases of external otitis. Meyer first described the fungal infection of the external auditory canal in the year 1884. Since then most of the aspects of this clinical entity have been thoroughly dealt with, however, it has been a neglected dis- ease and proper attention has not been given to it despite its common prevalence. It is worldwide in distribution but more common in tropi- cal and subtropical countries, particularly during the monsoon (rainy) season. Although this is rarely a potentially life-threatening disease but can present a challenging task and frustrating situation for the otologist as well as patients due to its high recurrence. Otomycosis is seen more frequently among immunocompromised patients as compared to immunocompetent individuals. It is mostly unilateral but sometimes there is bilateral involvement also, which is more commonly seen in the immunocompromised patients, wherein recurrence rate is also high. It is usually seen among swimmers. The other predisposing factors include use of steroids, dermatological dis- eases like dermatophytosis, loss of cerumen, use of topical broad- spectrum antibiotics, instrumentation of the ear and hearing aids. Classically, it is the result of prolonged treatment of bacterial otitis externa that alters the normal flora of the ear canal leading to mixed bacterial and fungal infection. However, fungus is the primary patho- gen in otitis externa, in the presence of excessive moisture or warmth. Otomycosis in the absence of bacterial complication is mani- fested by exfoliation of epithelium, itching and inflammation besides partial deafness when a plug of fungal hyphae and epithelial debris occludes the ear canal. This disease is generally caused by Aspergillus and Candida species, A. niger being the leading cause. Aspergillus spp. are the most com- monly involve the immunocompetent individuals and Candida spp., the immunocompromised group. However, fungi like Scopulariopsis brevicaulis, Aspergillus sclerotiorum, Malassezia are also rarely isolated. Sometimes true fungi may cause the infection like coccidioidomycosis of the external ear. Dermatomycoses accompany otomycosis in about 36.5% of the cases and the same pathogenic fungi are isolated in nearly half of them. Malignant otitis externa is generally caused by Pseudomonas aeruginosa and more rarely by other organism like Sce- dosporium apiospermum, Malassezia sympodialis, mucormycetes, etc., which eventually may prove fatal also, if not timely managed. Otomycosis needs to be differentiated from similarly looking clinical entities such as bacterial otitis externa, seborrheic dermatitis, impe- tigo, furunculosis and contact dermatitis. The clinical presentation, predisposing factors, mycological profile and treatment outcomes are very pertinent to establish its accurate diagnosis and thereby proper management. The diagnosis is not very difficult and conventional techniques like KOH/CFW wet mounts are used in the diagnostic mycology laboratory for the demonstration of fungi in the clinical material. The fungal cultures are essential to confirm the diagnosis. In case of biopsy specimens from the adjoining infected sites are received; H&E, PAS and GMS stainings are essentially required to establish the diagnosis. Moreover, rapid assay using fungal-specific monoclonal antibodies to detect fungi in ear swabs by immunofluo- rescence microscopy may also be utilized. The treatment of otomycosis in general consists of the removal of fungal debris and cleaning of ear canal together with reduction in humidity through insufflation of antifungal agents such as nystatin, clotrimazole, ketoconazole, fluconazole and amphotericin B. Mercuro- chrome, ciclopiroxolamine cream/solution (1%) and silver nitrate gel (1%) have also been found to be very fruitful. If fungal debris in the ear canal is too much, it has to be manually removed by suction or syringing so that antifungal regimen is effectively applied. In immu- nocompromised patients, it is important that the treatment of otomy- cosis be vigorous, to minimize complications such as hearing loss, tympanic membrane perforations and invasive temporal bone infec- tion. The clinical as well as mycological cures are to be achieved for successful outcome among these patients. Aspergillus infections may be resistant to clotrimazole and may require the use of systemic itrac- onazole or voriconazole.
Full conference title:
6th Trends in Medical Mycology 2013
- TIMM 6th (2014)