Healthcare-associated fungal outbreaks: New and uncommon species, New molecular tools for investigation and prevention

Outbreaks of healthcare-associated fungal infections have repeatedly been described over recent years, often caused by new or uncommon species. Candida auris, a recently described multidrug-resistant yeast species, is certainly the most worrisome species having caused several severe healthcare outbreaks of invasive infections, on four continents. Also, large nosocomial outbreaks due to uncommon fungal species such as Exserohilum rostratum and Sarocladium kiliense, were both linked to contamination of medical products, however the source of another outbreak, caused by Saprochaete clavata, remains unresolved. Furthermore, these outbreaks identified new populations under threat in addition to those commonly at risk for invasive fungal infections, such as immunosuppressed and intensive care unit patients. All of these outbreaks have highlighted the usefulness of a high level of awareness, rapid diagnostic methods, and new molecular typing tools such as Whole Genome Sequencing (WGS), prompt investigation and aggressive interventions, including notification of public health agencies. This review summarizes the epidemiological and clinical data of the majority of healthcare-associated outbreaks reported over the last 6 years caused by uncommon or new fungal pathogens, as well as the contribution of WGS as support to investigate the source of infection and the most frequent control measures used.