Aspergillus otomycosis in an immunocompromised patient.

Abstract

Aspergillus niger, an opportunistic filamentous fungus, was identified as the cause of chronic unilateral otomycosis in a 55-year old, immunocompromised man who had been unresponsive to a variety of treatment regimens. The patient presented with intermittent otalgia and otorrhea and with a perforation of his left tympanic membrane. A niger was identified in a culture specimen obtained from the patient's left ear canal. In immunocompromised patients, it is important that the treatment of otomycosis be prompt and vigorous, to minimize the likelihood of hearing loss and invasive temporal bone infection.

Introduction

Although otomycosis is frequently encountered in otolaryngology, it is difficult to diagnose because of its nonspecific symptoms. It is also difficult to treat because recurrence is common. Predisposing factors to fungal infection include habitual instrumentation, dermatitis, and immunocompromising conditions. Pruritis is one manifestation, along with discomfort, tinnitus, hearing impairment, and discharge.

Aspergillus niger is the only organism that can be identified correctly by its characteristic appearance in the ear canal. A whitish, cotton-like material consisting of fungal hyphae and dusky black conidiophores, together with epithelial debris and exudates, is the hallmark of this condition.

Treatment options include local debridement, discontinuation of topical antibiotics, and the use of local or systemic antifungal agents.

Case report

A 55-year-old, immunocompromised man presented with a history of chronic left otitis media and multiple recurrent tympanic membrane perforations. He had been treated with numerous antibiotics and antifungal drops over a period of several years and during that time underwent a transcanal tympanoplasty and resection of a middle ear cholesteatoma. The patient's recovery was complicated by infection and graft failure.

A couple months later, the patient was scheduled for revision tympanoplasty of his left ear. His ear was free of infection 1 week preoperatively, but examination in the operating room revealed obvious otomycosis (figure). The planned tympanoplasty was postponed, and a culture specimen obtained from his left inner ear canal showed the presence of A Niger. The patient responded quickly to treatment with fluconazole and clotrimazole drops.

Discussion

The correct diagnosis of otomycosis requires a high index of suspicion, given that the most common presenting symptoms, otalgia and otorrhea, are nonspecific. Aural fullness and hearing loss are also common in patients with this disease because of the accumulation of fungal debris in the ear canal.

Many authors have reported the identification of Aspergillus isolates in specimens obtained from the ears of patients with otomycosis. (1-4) Vennewald et al studied fungal colonization of the ear in 128 immunocompetent patients supposed to suffer from otomycosis. (5) Patients with chronic otitis media, with or without cholesteatoma, comprised the largest group in this study. The researchers argued that the predominance of Aspergillus and Candida spp is related to the inflammatory process of the ear. (5)

In patients with otitis media, persistent discharge with maceration of epithelium may support fungal colonization of the external ear. The presence of conidiophores in the auditory canal suggests that the fungi use the discharged mucus as a nutrient.

The inflammation caused by chronic hyperplasia of the mucous membrane in the middle ear can be compared with inflammation in the upper respiratory tract. (6-8) This condition is characterized by goblet cell metaplasia, increased mucus production, inhibition of mucociliary clearance, chronically inflamed mucosa with lymphocytic and plasma-cell inflammation, and fibrosis. This results in a disturbance of the continuous drainage of fluids from the middle ear cavity to the auditory tube, perforation of the tympanic membrane, and relapsing otorrhea.

Infection by molds, in contrast to that caused by bacteria and yeasts, usually occurs in the presence of tympanic perforation. In immunocompetent patients this is a rare event, but in immunocompromised patients, in whom this occurs more frequently, it is important that the treatment of otomycosis be prompt and vigorous in order to minimize the likelihood of hearing loss and invasive temporal bone infection. (9)

A study by Jackman et al assessed the contribution of ototopical antibiotic drops to the development of otomycosis. (10) Their research revealed that ofloxacin may contribute to the development of otomycosis in two ways. First, this agent is bactericidal to most bacteria in the external auditory canal, and fungal proliferation may occur because of the lack of competing bacterial growth. Second, in contrast to other topical otic antibiotics, which typically have a pH of 3 to 4, ofloxacin has a pH of 7. This more neutral solution does not acidify the pH of the external auditory canal skin, making it a more optimal environment for fungal proliferation (Aspergillus grows optimally at a pH of 6). These two properties of topical ofloxacin may explain its association with otomycosis.

Several studies have reported on the effectiveness of various antifungal agents for ear infections, both in vivo and in vitro. Stern et al found clotrimazole to be the most effective agent against common ear fungal organisms in vitro. (11) Other clinical studies have found clotrimazole to be the most effective antifungal agent in vivo, followed by gentian violet and nystatin. (12) Clotrimazole also showed the greatest efficacy in Jackmen's study. (10) In several cases, multiple drug therapies were used, and patients required multiple follow-up visits before their infections were cleared. (11)

Although multiple in vitro studies have examined the efficacyofvarious antifungal agents, no consensus exists as to which is the most effective agent for otomycosis. (11,13) Treatment with appropriate topical antifungal agents, coupled with frequent mechanical debridement, usually results in the resolution of the symptoms of otomycosis, although recurrence or residual disease is common.

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Tympanic membrane perforation also may occur as a complication of otomycosis that starts in an ear with an intact ear drum. The pathophysiology of this occurrence has been attributed to avascular necrosis of the tympanic membrane as a result of mycotic thrombosis in the tympanic membrane blood vessels. (14)

In conclusion, the diagnosis of otomycosis can be challenging given its nonspecific symptoms. Recurrence after treatment is not uncommon, and eradication of disease can be particularly difficult in postmastoidectomy patients. (15) Otolaryngologists should remain alert for otomycosis and should consider obtaining cultures when this disease is suspected.

References

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Amy L. Rutt, DO; Robert T. Sataloff, MD, DMA

From the Department of Otolaryngology-Head and Neck Surgery, Huron Valley-Sinai Hospital/Detroit Medical Center, Detroit, Mich. (Dr. Rutt) and the Department of Otolaryngology-Head and Neck Surgery, Drexel University College of Medicine, Philadelphia (Dr. Sataloff).

Corresponding author: Robert T. Sataloff, MD, DMA, 1721 Pine St., Philadelphia, PA 19103. Phone: [phone]; fax: [phone]; e-mail: [e-mail]