Otomycosis: causes, symptoms, diagnosis, and treatment

Otomycosis is an acute, subacute, or chronic fungal infection in the auricle and external auditory canal.


Causes

The pathogens causing external auditory canal infections are mostly aspergillus fumigatus and aspergillus niger, and aspergillus niger accounts for over 90%. Other pathogens include candidas, scopulariopsis, penicillium, mucor, aspergillus flavus, malassezia, absidia, acremonium, rhizomucor, and syncephalastrum. In 80% - 90% of external otitis, various bacteria, such as pseudomonas, proteus, micrococcus, streptococcus, escherichia coli, and corynebacterium, can be found. These bacteria in combination with fungi aggravate the fungal infections.

Local preexisting skin lesions, such as eczema, psoriasis, and seborrheic dermatitis in the external auditory canal, local moisture, and external auditory canal lesions caused by ear picking or long-term use of topical antibiotics and corticosteroids are important inducing factors.

The fungi that cause auricle infections are mainly dermatophytes such as trichophyton rubrum, trichophyton gypsum, and microsporum lanosum, resulting from tinea capitis, tinea faciei, tinea manuum, tinea pedis, and onychomycosis.


Signs and Symptoms

Tinea of the auricle

Initial red papules and vesicles are followed by desquamation, gradually extending peripherally into large, sharply demarcated erythema, covered with scales, with papules or vesicles, which can extend to the external auditory canal, whole ears, neck, and face. Some patients have a history of use of topical corticosteroids. Subjective symptoms are obvious pruritus. Skin lesions are usually unilateral, and may be accompanied by tinea capitis, tinea faciei, tinea manuum, or tinea pedis. Branched, septate hyphae in scales can be seen in KOH examination.

Otomycosis externa

Otomycosis externa is caused by fungi other than dermatophytes. If the pathogens are dermatophytes, the illness should be known as tinea in the external auditory canal. Otomycosis externa is mainly manifested by erythema, scales, edema, or scabs. Cerumen accumulation and subjective pruritus are present, and fullness or hearing loss, sometimes pain are present. If with bacterial infection, there are pus and odor, and auricular cartilage can be involved in severe cases.

The scabs in the external auditory canal are mostly cannular, with villiform or powdery fungus growing on the surface, and the color is black, yellow, green, or grayish brown depending on the different pathogens. After removal of the crusts, the epidermis is red and swollen, with mild erosion. Congestion, thickening, or secretions may be present in the tympanum.

Figure 1 otomycosis

Hyphae and spores can be seen in KOH examination with cerumen or scales, and sometimes conidial head can also be found.


Diagnosis

On the basis of clinical findings and positive fungal microscopy, the disease can be diagnosed.


Treatment

Otomycosis is generally treated with topical medications, unless the middle ear or middle ear cavity is involved, topical medications are poorly effective, or debridement and systemic antifungals are required.

Otomycosis is mainly treated with topical medications, such as 2% miconazole cream, bifonazole cream, 1% clotrimazole ointment, 5% nystatin ointment, 5% pimaricin ointment, 1% aureofucinum ointment or solution, 10 mg/mL flucytosine solution, 1% ketoconazole ointment, tolnaftate, and 0.1% thimerosal ointment. If the topical medications are poorly effective, oral itraconazole is appropriate.

In the treatment of otomycosis externa, before administration of the topical medications, removal of crusts and cerumen followed by rinse of the external auditory canal with 3% hydrogen peroxide solution or 5% aluminum acetate solution should be performed. If necessary, debridement followed by intravenous fluconazole 200 mg/d or miconazole 200mg diluted with 250mg of 5% glucose can be considered.