Twenty-two fungal infections that were in the squeeze bottle

Purpureocillium lilacinum is a common environmental mould. Skin
infections with it are rare, and mostly occur in immunocompromised people.

In 2024, a Washington dermatology clinic reported **22 patients whose
cultures yielded P. lilacinum**.

Twenty-two cases of a rare infection, in one clinic, in one year. That is
either an outbreak or a mistake.

It was a mistake

**The clinic was collecting skin swab specimens to diagnose fungal skin
infections, rather than the recommended biopsy or skin scraping specimens.**

**All the swab specimens were contaminated by saline from squeeze bottles that
clinic staff had repeatedly refilled and reused during specimen collection.**

**Whole genome sequencing showed the isolates from the patients' swabs and
from the contaminated bottles were closely related.** And the conclusion:
**no patient received confirmation of clinical infection with *P.
lilacinum*.**

A pseudo-outbreak — an outbreak of positive results without an outbreak of
disease.

Why it matters that nobody was ill

A pseudo-outbreak is not harmless. Twenty-two people were told they had a rare
fungal skin infection. Some will have been treated for it — antifungals are
not trivial drugs — and whatever was actually wrong with their skin went
undiagnosed while the wrong answer was being acted on.

It also consumed an investigation: a health department, a CDC laboratory and
genome sequencing, to establish that nothing was happening.

The two failures

1. The wrong specimen type. Swabs were used where **biopsy or skin
   scraping** is recommended. A swab collects what is on the surface,
   including whatever the surface was just wetted with.
2. The reused bottles. Saline squeeze bottles repeatedly refilled and
   reused are a reservoir, and a mould that lives in the environment will
   eventually find one.

The stated implication is plain: **proper specimen collection procedures,
diagnostic practices, and infection prevention and control measures are
critical to providing recommended care.**

*Source: Yomogida KS, Laskowski E, Hannah L, et al. Pseudo-Outbreak of
Purpureocillium lilacinum Skin Infections at a Dermatology Clinic —
Washington, 2024. MMWR, Centers for Disease Control and Prevention.*