Background: Nosocomial infections represent a significant clinical burden due to high morbidity, mortality and healthcare costs. Invasive fungal infections, particularly those caused by Candida species, are of growing concern due to increasing antifungal resistance, which limits therapeutic options and worsens patient outcomes. This study aimed to characterize the prevalence, species distribution, antifungal susceptibility profiles, and molecular mechanisms of resistance in clinical Candida isolates from hospitalized patients. Methods: A cross-sectional study was conducted involving 55 hospitalized patients, yielding 60 isolates from blood, secretions, fluids, and catheter tips. Species identification was performed using chromogenic media and confirmed by MALDI-TOF MS. Antifungal susceptibility testing followed CLSI M27-A4 broth microdilution guidelines for amphotericin B, fluconazole and 5-flucytosine. Gene expression of ERG2, ERG11 and MDR1 was evaluated by RT-qPCR after exposure to subinhibitory antifungal concentrations using the 2^−∆∆Ct method. Results:Candida albicans was the most frequent species, followed by Nakaseomyces glabratus, C. tropicalis and C. parapsilosis. Resistance varied among species, with elevated rates for fluconazole. ERG2 was notably overexpressed in amphotericin B-resistant isolates, while ERG11 and MDR1 showed species-dependent variation. Conclusions: Resistance mechanisms in Candida are species-specific and drug-dependent. Accurate species identification and understanding their molecular profiles are essential to guide targeted antifungal therapy and improve clinical outcomes.

Candida species can shift from commensal organisms to opportunistic pathogens. Both Candida albicans and non-albicans Candida (NAC) species colonize oral biofilms and periodontal pockets, where they may contribute to inflammation and the progression of periodontal disease. This study aimed to determine the prevalence and antifungal susceptibility profiles of Candida species in individuals with different stages of periodontal disease. A cross-sectional study was conducted in 100 participants whose periodontal status was clinically evaluated. Saliva samples were cultured on chromogenic agar for yeast isolation, species identification was confirmed by MALDI-TOF MS, and antifungal susceptibility to fluconazole, clotrimazole, nystatin, and amphotericin B was assessed. Candida spp. was detected in 35% of participants, where C. albicans was the most prevalent species, followed by Nakaseomyces glabratus (formerly Candida glabrata), Candida parapsilosis, Candida dubliniensis, and Candida tropicalis. Species distribution varied according to periodontal status, with N. glabratus predominating in early periodontitis and C. albicans appeared more frequently in higher severe stages of periodontitis. Susceptibility testing showed resistance of C. albicans to clotrimazole (63.6%) and nystatin (22.7%), whereas amphotericin B and fluconazole remained effective. NAC species, particularly N. glabratus, exhibited resistance to nystatin and variable resistance to clotrimazole but remained susceptible to amphotericin B. These findings underscore the importance of early detection and personalized antifungal strategies for managing periodontal disease complicated by Candida colonization.