Candida auris Outbreak and Epidemiologic Response in Burn Intensive Care Unit, Illinois, USA, 2021-2023.

Candida auris is an emerging fungal pathogen associated with outbreaks in healthcare settings. We report a multiyear outbreak of C. auris in a burn intensive care unit in Illinois, USA, during 2021-2023. We identified 28 C. auris cases in the unit over a 2-year period, despite outbreak response and multimodal mitigation measures. Of the 28 case-patients, 15 (53.6%) were considered colonized and 13 (46.4%) had clinical infections. Phylogenetic analysis of whole-genome sequences revealed 4 distinct clusters of closely related (0-6 SNP differences) genomes containing 3-6 cases. Clusters generally contained temporally related isolates from patients with epidemiologic links; this finding suggests that multiple introductions and within-unit spread over a limited time were responsible for the outbreak, rather than transmission from a long-term source (e.g., persistent environmental contamination or staff carriage). Here, integrated traditional and genomic epidemiology supported C. auris outbreak investigation and response and informed targeted interventions.