The prevalence and antifungal susceptibility profile of <i>Candida dubliniensis</i> and <i>Candida albicans</i> in the respiratory tract of patients with cystic fibrosis

Respiratory infections are the leading cause of mortality and morbidity among cystic fibrosis (CF) patients. Pathogenic bacteria and fungi such as <i>Pseudomonas aeruginosa</i>, <i>Staphylococcus aureus</i>, and various yeasts as well as filamentous fungi are commonly identified opportunistic microorganisms recovered in the sputa from CF patients. The clinical significance of yeasts, particularly <i>Candida</i> species, in patients with CF is not fully understood. Furthermore, the emergence of antifungal resistance in clinical settings is a global concern. This study aimed to determine the prevalence of <i>Candida</i> species with special focus on <i>Candida dubliniensis</i> and <i>Candida albicans</i> in sputum samples from patients with CF and evaluate their susceptibility to antifungal agents. A total of 968 culture-positive sputum samples were collected from 193 patients with CF over a period of 1 year. Fungal isolates were identified to the species level using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. The antifungal susceptibility of <i>Candida</i> isolates was determined using Sensititre YeastOne panels. The most commonly isolated yeast species in these sputum samples were <i>C. dubliniensis</i> (13%) and <i>C. albicans</i> (32%). Colonization with <i>C. dubliniensis</i> or <i>C. albicans</i> was not associated with a deteriorated lung function. Voriconazole had the lowest minimum inhibitory concentration (MIC) against <i>C. dubliniensis</i> and <i>C. albicans</i>. Itraconazole showed higher MIC values to <i>Candida albicans</i>. An increased understanding of the antifungal susceptibility profiles of <i>Candida</i> species isolated from CF patients may provide valuable knowledge about treatment of yeast infections in this patient group.IMPORTANCEOur findings indicate that colonization with <i>Candida dubliniensis</i> and <i>Candida albicans</i> does not exert a significant impact on pulmonary function in individuals with cystic fibrosis. Furthermore, antifungal resistance among the isolated <i>Candida</i> species was generally low.