Detection and Antifungal Susceptibility of Fungal Pathogens Associated with Otomycosis in a Tertiary Health Center in Kano, Nigeria.

Introduction

Otitis externa is estimated to account for 5-20% of all ear-related visits to Ear, Nose, and Throat (ENT) clinics, of which 10-25% were attributed to otomycosis. Our study aimed to identify the fungal pathogens associated with otomycosis and to evaluate their antifungal susceptibility in a low-resource-setting community.

Methods

The study was conducted in the Department of Medical Microbiology and Parasitology, Bayero University Kano, Nigeria, from January to June 2024. A total of 300 patients with a clinical diagnosis of otitis externa were recruited from the otorhinolaryngology clinic of Aminu Kano Teaching Hospital. Two swab samples were collected from each patient for mycological examinations. The first swab was evaluated for microscopy using KOH mount and Gram Staining. The second swab was subjected to fungal culture on SDA. Isolates were identified using other mycological examinations where necessary, including the sequencing of the fungal rDNA. In vitro AFST against Amphotericin B, Fluconazole, Itraconazole, Voriconazole, Ketoconazole, and Nystatin was performed using the disk diffusion method according to the CLSI guidelines.

Results

Out of 300 patients, 117 subjects (39.0%) were mycologically positive. Females (69.0%) and the age group ≤10 years (44.3%) were the most affected. Cases were predominantly unilateral in 285 (95%) patients involving the right ear (71.7%). Ear itching (95.7%) and pain (89.0%) were the most common presentations. The markedly observed risk factors were frequent ear cleaning (88.0%) and ear manipulation with a foreign object (76.3%). Aspergillus species and Candida species were present in 90 (77.0%) and 27 (23.0%) cases, respectively. Isolates showed high sensitivity to Voriconazole and Nystatin but poor response to Ketoconazole and Fluconazole.

Conclusion

Otomycosis accounts for 39% of otitis externa seen in our center, mostly presenting with pruritus and otalgia. Awareness campaigns to the general population on predisposing factors might significantly reduce the incidence of otomycosis.