In 2024, a Washington dermatology clinic reported a pseudo-outbreak of Purpureocillium lilacinum skin infections affecting 22 patients who presented with rashes. Initial diagnoses were based on skin swab cultures, which are not recommended for confirming fungal skin infections. An investigation by the Washington State Department of Health and CDC revealed that the clinic's practice of refilling and reusing saline squeeze bottles for specimen collection led to contamination of the saline with P. lilacinum. Whole genome sequencing confirmed the close relatedness of isolates from patient swabs and environmental samples. The clinic transitioned to single-use saline packets, and no further cases were reported.
Key note: Proper specimen collection procedures and infection prevention are critical to avoid misdiagnosis and pseudo-outbreaks.