Candida Species as Opportunistic Pathogens: Epidemiology, Virulence, Laboratory Diagnosis, and Antifungal Resistance

Candida species are among the most common opportunistic fungal pathogens affecting humans, particularly immunocompromised individuals. While Candida albicans has historically been the predominant etiological agent of candidiasis, recent epidemiological trends indicate a significant rise in infections caused by non-albicans Candida species, many of which exhibit intrinsic or acquired resistance to commonly used antifungal agents. These yeasts, which normally exist as commensals within the human microbiota, can transition to pathogenic forms under favourable host or environmental conditions. This review provides a comprehensive overview of the clinical and epidemiological features of Candida infections, with emphasis on laboratory diagnosis, virulence mechanisms, and antifungal resistance. Conventional and advanced diagnostic methods, including culture-based techniques, phenotypic tests, and molecular assays, are critically discussed. The growing challenge of antifungal resistance, biofilm-associated infections, and emerging multidrug-resistant species such as Candida auris is also addressed. Understanding these evolving dynamics is essential for improving patient outcomes, guiding antifungal therapy, and informing public health interventions