Emergent Candida Species on Healthcare Surfaces: Abiotic Reservoirs as a Source of Invasive Candidiasis

The aetiology of invasive candidiasis is undergoing substantial changes; traditionally, these mycoses have been considered to originate from endogenous reservoirs; however, the increasing prevalence of non-Candida albicans species, such as Candida parapsilosis and Candida auris (also named Candidozyma auris), is a cause of concern as they demonstrate significant exogenous transmission. This challenges the long-standing paradigm of endogenous origin in hospital settings. Unlike previous reviews primarily focused on clinical epidemiology, this work adopts a multidisciplinary perspective combining microbiological evidence with biomaterials science. We analyse how surface roughness, hydrophobicity, and polymer composition within the hospital "plastisphere" influence Candida adhesion and the formation of dry surface biofilms (DSBs). In this specific context, in contrast to C. albicans, primarily associated with mucosal colonisation, C. auris and C. parapsilosis exhibit distinctive adaptations that promote survival in healthcare environments, including pronounced cell surface hydrophobicity and the capacity to form dense cellular aggregates, which facilitate prolonged adherence to synthetic polymers used in medical devices. We also explore the biological mechanisms underlying this resilience, with particular emphasis on the development of dry surface biofilms and viable but non-culturable states. These phenotypic traits confer tolerance to desiccation and resistance to conventional disinfectants, raising concerns that standard hygiene and decontamination protocols may be inadequate to prevent transmission. Understanding these mechanisms is essential for designing effective infection control strategies and mitigating the risk of invasive disease caused by these highly persistent species.