Candida and Candidosis: Updates on Epidemiology, Diagnosis, Treatment, Antifungal Drug Resistance, and Host Genetic SusceptibilityCandida species are eukaryotic fungal pathogens known to be aetiological agents of opportunistic and nosocomial infections in humans worldwide. Candida spp. are the fourth most common cause of nosocomial bloodstream infections acquired in hospitals in the United States. In Europe, candidemia rates vary between 1.2 and 11 per 100.000 population. There are over 200 species of Candida yeasts; among them, Candida albicans is the most common cause of disseminated and non-invasive mucocutaneous diseases. However, the incidence of candidosis due to non-albicans Candida spp. is increasing, including: C. glabrata, C. parapsilosis, C. tropicalis, C. krusei, C. lusitaniae, C. dubliniensis and C. guilliermondii. The clinical outcome of Candida infections is primarily determined by the host's defense status and can be divided into mucocutaneous infections and deep-seated infections. Mucocutaneous infections include thrush, Candida esophagitis, nonesophageal gastrointestinal candidosis, Candida vaginitis, and cutaneous candidosis syndromes. Deep-seated infections include chronic disseminated candidosis (hepatosplenic candidosis), candidemia, and candidosis of various organ systems. The fungus is capable of secreting proteinases and lipases that can assist invasion, although the clinical importance of these enzymes is not clearBoth the Mycoses Study Group of the Infectious Diseases Society of America (IDSA) and the Infectious Diseases Group of the European Organisation for Research and Treatment of Cancer (EORTC) have published practice guidelines for the treatment of invasive candidosis in various patient populations. Of note, antifungal drug resistance was an important factor that needed to be considered for treatment. Candida spp. became resistant to antifungal agents due to the expression of efflux pumps that reduces drug accumulation, alteration of the structure or concentration of antifungal target proteins, and alteration of membrane sterol composition. Moreover, despite the important role played by general risk factors, i.e., an immunocompromised immune system, they did not explain all cases of infection. Several studies reported a link between genetic variation and an increased risk for Candida infections, with a different genetic pattern being discerned between mucosal and systemic candidosis. This article summarizes up-to-date information on the epidemiology, diagnosis, and treatment of infections caused by the genus Candida, as well as antifungal drug resistance and host genetic susceptibility in affected patients.