Antifungal Susceptibility Pattern of Fungi Isolated from Patients with Otomycosis Attending a Tertiary Health Care Institution in Sokoto, Nigeria

Abstract

Background: Antifungal therapy is an important component of patient management for acute and chronic mycoses. However, treatment choices are restricted because of the scanty number of antifungal drug classes. Medical treatment of otomycosis is further compromised by the emergence of antifungal drug resistance, and these limits available drug classes as treatment options. Once considered a rare occurrence, antifungal drug resistance is on the rise in many high-risk medical centers. Most concerning is the evolution of multidrug-resistant organisms refractory to several different classes of antifungal agents, especially among common Candida species. Aim: This study seeks to identify the fungal species implicated in otomycosis among patients attending a tertiary health-care institution in Sokoto, Nigeria and determine its susceptibility pattern using commonly used antifungal agents. Methods: A descriptive, cross-sectional, hospital-based study was conducted on 100 patients with otitis externa. The ear discharge specimens were collected and analyzed using the standard microbial techniques. The antibiotic susceptibility profiles were determined for 12 different antifungal by the standard disk diffusion method. Data were analyzed using the SPSS software version 25 and the P < 0.05 was considered as statistically significant. Results: One hundred and twenty-four external ear discharge samples were collected from either right ear, left ear, or both ears (some patients has unilateral while others have bilateral disease and those with bilateral disease, samples were taken from the two ears). Aspergillus niger 30 (40.0%) was the most commonly isolated fungi in this study, followed by Candida spp. 25 (33.3%), Aspergillus fumigatus 5 (6.7%), Mucor 5 (6.7%), Penicillum 4 (5.3%), Aspergillus flavus 3 (4.0%), and Rhizopus 3 (4.0%) %). The isolated fungi were tested for antifungal sensitivity to 6 antifungal discs. A. niger shows good susceptibility to clotrimazole (100%), nystatin (90%), and fluconazole (83.3%) but was resistant to griseofulvin, terbinafine, and ketoconazole. A. flavus and A. fumigatus also show good sensitivity to clotrimazole, nystatin, and fluconazole. Candida albicans was only susceptible to clotrimazole but resistant to other tested antifungal disc. Rhizopus and Penicillum species showed 100.0% sensitivity to clotrimazole but also resistant to other tested antifungal discs. Conclusions: This study revealed that Aspergillus and Candida species were the most common fungal pathogens causing otomycosis. A. niger is the predominant fungal isolate. Molds isolates showed good susceptibility to clotrimazole, while highest resistance was to terbinafine and ketoconazole. Yeasts isolates showed highest susceptibility to clotrimazole and highest resistance to nystatin and fluconazole.