Epidemiology of Onychomycosis in Pernambuco, Northeastern of Brazil: Results of a Laboratory-Based Survey

Abstract

Onychomycosis is chronic ungual disease that affects people worldwide and whose prevalence has been increasing in recent decades. Among the etiological agents are yeasts, dermatophytes and non-dermatophytid filamentous fungi (NDFF). The symptoms and severity can vary widely according to the anatomic site, condition of the individual and geographic location. Laboratory identification of the fungal etiological agents is necessary due to the wide variety of these agents and the varied responses to the existing drugs. This study aimed to diagnose and characterize epidemiologically onychomycosis, besides of to determine the susceptibility profile against evaluable antifungals drugs. Patients of a Dermatological Public Service of reference at Recife city, Northeast of the Brazil, which were suffering from suggestive lesions were evaluated between August 2016 and July 2017. Mycological diagnosis was carried out by direct microscopic examination of clinical samples clarified with 20% potassium hydrochloride (KOH) and by culture in Sabouraud dextrose agar medium supplemented with 2% (v/v) chloramphenicol. After incubation for 15 days at 35-37 °C, the macro and microscopic aspects of the colonies were analyzed for specie identification. The yeasts were identified by proteomic analysis with MALDI-TOF MS. In vitro antifungal susceptibility testing was carried out according CLSI method. Signs and symptoms suggestive of onychomycosis were presented in 196 patients, of which were obtained 224 nail samples. In the mycological tests, 119 samples from 108 patients were diagnosed positively for onychomycosis, of them 77 (39.28%) from females, and the hand (fingernails) was the region most often affected, with 61 cases (31.12%). The etiological agents isolated most frequently were yeasts of Candida with 92 cases (77.31%), followed by non-dermatophytic fungi with 19 cases (15.97%), especially the genus Fusarium with 17 cases (14.28%), and dermatophytes with 8 cases (6.72%). Candida yeasts were the most prevalent etiological agents and the area most affected was the hand, associated with homemakers, who typically have greater contact with humidity. Onychomycosis caused by dermatophytes was least frequent, however terbinafine was the drug of choice for therapy in patients and in vitro more effective against dermatophytes. Most of the patients had been submitted to ineffective treatment. The yeasts were more susceptible to the antifungals and NDFF were the more resistant to the antifungals. The prescription of drug combinations can be a solution for treatment of onychomycosis caused by NDFF. The patients’ reports of longstanding symptoms indicate the chronic nature of the disease and the profile can change frequently, suggesting that periodic analyses are necessary. The frequent recurrences can be related to the high cost and long treatment periods, while public awareness campaigns can help to reduce infection rates..