Efficacy of topical isoconazole nitrate in the treatment of otomycosis

Etiology, Predisposing Factors, Clinical Features and Diagnostic Procedure of Otomycosis: A Literature Review

Otomycosis (OM) is a superficial fungal infection of the external auditory canal (EAC) with a worldwide prevalence ranging from 9% to 30%. Commonly, otomycoses are caused by Aspergillus (A.) niger complex and Candida spp. Other causative agents are yeasts of the genera Cryptococcus spp., Rhodotorula spp., Geotrichum candidum, dermatophytes (Trichophyton mentagrophytes), and non-dermatophytes molds (Fusarium spp., Penicillium spp., Mucorales fungi). The widest range of different species causing OM are found in the territories of Iran, India, China, Egypt, Mexico, and Brazil. Fungal infection of the EAC varies from mild to severe forms. It can be acute, subacute, or chronic, and is often unilateral, while the bilateral form is more common in immunocompromised patients. From an epidemiological point of view, tropical and subtropical climates are the most significant risk factor for the development of otomycosis. Other predisposing conditions include clothing habits, EAC hygiene practices, long-term antibiotic therapy, diabetes, and immunodeficiency. Since it is often difficult to distinguish otomycosis from an infection of a different origin, laboratory-based evidence, including standard procedures (microscopy and cultivation), is essential for diagnosis. For the treatment of this superficial fungal infection, there are no official therapeutic guidelines and protocols. However, many antifungals for local application, such as polyene, imidazoles, and allylamines, can be applied, as well as systemic antimycotics (triazoles) in severe forms of infection.

Otomycosis: The foremost aetiological agent causing otitis externa and the antifungal susceptibility pattern in North-Western Iran

BACKGROUND

Otomycosis is considered a recurring fungal ear infection. The external auditory canal provides an appropriate and optimal situation for fungal growth.

OBJECTIVES

The study aimed to identify the causative agents of otomycosis and determine corresponding antifungal drug susceptibility patterns in north-western Iran.

METHODS

From October 2020 until November 2021, 200 patients attended an otolaryngology referral centre with otitis externa, and their ear discharge and debris were examined and cultured. The identification of the fungal agents was implemented by polymerase chain reaction-restriction fragment length polymorphism and sequencing. In vitro antifungal susceptibility testing of the isolates was conducted in accordance with the CLSI broth microdilution protocols.

RESULTS

The prevalence of otomycosis was measured 50.5% (n = 101/200). The majority of patients were in their forties (n = 35, 34.6%) and female (n = 57, 56.4%), and the most prevalent symptom was otalgia (56.4%). The most underlying factor was remarked manipulation employing a cotton swab (65.3%). Regarding fungus, Aspergillus section Nigri (58.57%) was the foremost isolate, followed by Aspergillus section Flavi (19.23%) and Candida parapsilosis (14.96%). The predominance of Aspergillus isolates had minimal in vitro sensitivity to tioconazole and nystatin. Candida species represented higher geometric mean minimum inhibitory concentrations (MIC) against nystatin. The MIC of three Aspergillus species isolates shown above the epidemiologic cut-off values (ECV) against itraconazole.

CONCLUSIONS

Otomycosis incidence surpassed in comparison with the previous study as the most common cause of otitis externa. The MIC distribution of Aspergillus species isolates against triazole antifungals is close to the defined ECVs and likely outrun it over time.