The Prevalence and Drug Susceptibility of Candida Species and an Analysis of Risk Factors for Oral Candidiasis—A Retrospective Study
Marcin Tkaczyk, Anna Kuśka-Kiełbratowska, Jakub Fiegler-Rudol, Wojciech Niemczyk, Anna Mertas, Dariusz Skaba, Rafał Wiench
Abstract
Background: Oral candidiasis is a prevalent opportunistic infection, predominantly caused by Candida albicans (CA), though non-albicans Candida (NAC) species are increasing worldwide. This study aimed to characterize the prevalence of Candida species, evaluate antifungal susceptibility, and identify predisposing risk factors in patients with oral mucosal candidiasis. Methods: A retrospective review of 1286 electronic patient medical records (788 women, 498 men) from 2018 to 2022 was conducted at the Department of Periodontal and Oral Mucosa Diseases, Medical University of Silesia. Swabs from the oral cavity were processed to identify Candida strains by mass spectrometry, followed by drug susceptibility testing for amphotericin B, nystatin, flucytosine, econazole, ketoconazole, miconazole, and fluconazole. Relevant local and systemic predisposing factors were recorded and analyzed statistically. Results: Among 958 patients with positive fungal cultures, CA accounted for 66.79% of isolates, while NAC constituted 33.21%. Multi-strain infections were detected in 8.46% of patients. CA showed lower resistance (<10%) to amphotericin B, nystatin, and flucytosine, but up to 30% resistance to azoles. NAC strains demonstrated elevated resistance rates (>40% for most azoles), with C. krusei exhibiting the highest resistance to the previously mentioned antifungal agents. Key risk factors included wearing removable dentures (p = 0.042) and uncontrolled diabetes mellitus (p = 0.0431). Additional factors, including poor oral hygiene, reduced salivary flow, and immunosuppressive conditions, further increased infection risk. Patients presenting with multiple risk factors were more likely to have multi-strain infections and more severe disease courses. Conclusions: This retrospective analysis highlights the growing prevalence of NAC, rising antifungal resistance (particularly to azoles), and the importance of identifying risk factors, especially denture use and poor glycemic control. Enhanced preventive strategies, robust diagnostic approaches, and optimized antifungal regimens are essential to address this evolving clinical challenge.