Nosocomial outbreaks with rare yeasts: Trends, characteristics and preventive measures

This narrative review aims to aggregate all reports of nosocomial transmission of rare yeast species, to provide an overview of global trends, causative species, clinical characteristics and preventive measures.

A comprehensive literature search of multiple databases was conducted, to identify all reported nosocomial transmission events involving rare yeast species. The five most common yeasts, Candida albicans, Nakaseomyces glabratus, Candida parapsilosis, Candida tropicalis and Pichia kudriavzevii, in addition to Candida auris were excluded.

A total of 76 reports were retrieved since 1984, caused by 28 different species. Wickerhamoyces anomalus was the most common agent, followed by Magnusiomyces, Trichosporon and species of the Candida haemulonii complex. Since the early 2000s, a clear increase was noted both in the number of outbreak reports and range of associated species, largely due to improved diagnostics. Most species were resistant to one or multiple antifungals and although environmental sampling was often performed, virtually all efforts yielded negative results. Once noted, strict hand hygiene practices and proper cleaning and disinfection of medical equipment has shown in curbing nosocomial spread.

As hospital outbreak events are increasingly reported, accurate species identification and epidemiological surveillance should be in place for rapid detection. An enhanced focus on infection control measures was often sufficient to prevent new cases. Importantly, high-resolution genotyping is needed to confirm clonal transmission, which is often not conducted.