A rare fungal pathogen that can cause severe, treatment-resistant infection of the cornea and potentially destroy vision was identified as the cause of a healthcare-associated outbreak at an ophthalmology clinic in New York City in 2024, according to an investigation published in the CDC's Morbidity and Mortality Weekly Report in 2026. The outbreak, involving Purpureocillium lilacinum — a filamentous mold found naturally in soil and water that has no approved antifungal standard treatment protocol — affected multiple patients who underwent procedures at the same ophthalmology clinic and developed keratitis (corneal infection) as a healthcare-associated complication.
A companion MMWR investigation published simultaneously documented a pseudo-outbreak of Purpureocillium lilacinum skin infections at a dermatology clinic in Washington state, where investigation determined that the infections were not true healthcare-associated transmissions but rather consecutive community-acquired infections that had been identified through enhanced surveillance. The clinical distinction between the two investigations — a true outbreak at the ophthalmology clinic versus a pseudo-outbreak at the dermatology clinic — highlights both the complexity of healthcare-associated infection surveillance and the growing clinical importance of Purpureocillium lilacinum as a pathogen in clinical settings.
Purpureocillium lilacinum (formerly classified as Paecilomyces lilacinus) is an environmental mold that has emerged as a significant cause of healthcare-associated infection — particularly fungal keratitis following intraocular procedures, keratoplasty (corneal transplant), LASIK surgery, cataract surgery, and intravitreal injections — as well as catheter-associated infections and skin infections in immunocompromised patients. It produces infections that are notoriously difficult to treat because of its intrinsic resistance to amphotericin B, one of the primary broad-spectrum antifungals used against molds, and variable resistance to other antifungal drug classes.
Why Ophthalmology Clinics Are Particularly Vulnerable
The eye is uniquely vulnerable to fungal infection following any procedure that breaches its natural defenses. The cornea — the clear, dome-shaped outer surface of the eye — is normally protected by the tear film, blinking, and tight epithelial cell junctions. Any procedure that disrupts this barrier: LASIK flap creation, cataract lens removal, vitreoretinal surgery, intravitreal injections for macular degeneration or diabetic retinopathy, or corneal transplantation creates a window of vulnerability.
Fungal keratitis is among the most serious complications of ophthalmologic procedures. Unlike bacterial keratitis, which typically responds well to topical antibiotic drops started within hours of diagnosis, fungal keratitis progresses more slowly and responds poorly to treatment. Purpureocillium lilacinum keratitis in particular can be refractory to standard antifungal regimens because of the organism's resistance profile. Patients may require weeks to months of intensive topical antifungal therapy, surgical debridement, or in severe cases, penetrating keratoplasty (corneal transplant) to preserve vision. Despite aggressive treatment, some patients suffer permanent visual impairment.
The New York City ophthalmology clinic investigation follows a pattern seen in prior Purpureocillium healthcare-associated outbreaks: the organism is likely introduced through contaminated water, contaminated instruments or solutions, or environmental contamination in the procedure area, and then transmitted to multiple patients before the cluster is recognized. Infection control investigations in ophthalmology outbreaks typically require environmental sampling of water sources, sterilization equipment, instrument storage solutions, and surface swabs from procedure rooms.
What Patients Should Know Before Elective Eye Procedures
The practical message for patients scheduling elective eye procedures — LASIK, cataract surgery, intravitreal injections, or any intraocular or corneal surgery — is not to avoid these procedures, which are among the safest and most effective in medicine. It is to know the warning signs of post-procedure infection so they can seek care before serious vision loss occurs.
Any patient who develops increasing eye pain, redness, light sensitivity, tearing, blurred vision, or a visible white or gray spot on the cornea within days to weeks of an eye procedure should contact their ophthalmologist immediately and specifically mention the recent procedure. Fungal keratitis can be difficult to distinguish from bacterial keratitis on clinical examination, and culture of corneal scrapings is often required to identify the specific pathogen and guide appropriate antifungal therapy.
Frequently Asked Questions
Q: What is Purpureocillium lilacinum, and why is it dangerous?
A: P. lilacinum is an environmental mold that can cause severe eye infections (keratitis) and other healthcare-associated infections, particularly after eye procedures. It is intrinsically resistant to amphotericin B and may resist other antifungals, making it difficult to treat.
Q: What types of eye procedures are associated with this infection risk?
A: Any procedure that disrupts the eye's natural protective barriers, including LASIK, cataract surgery, intravitreal injections (for macular degeneration or diabetic retinopathy), corneal transplantation, and vitreoretinal surgery.
Q: What are the symptoms of fungal keratitis after an eye procedure?
A: Eye pain, redness, light sensitivity, tearing, blurred vision, and a white or gray spot visible on the cornea, appearing days to weeks after the procedure. These symptoms require immediate ophthalmologic evaluation.
Q: How is Purpureocillium keratitis treated?
A: With intensive topical antifungal therapy, chosen based on susceptibility testing since P. lilacinum is resistant to amphotericin B. Treatment may span weeks to months. Surgical debridement or corneal transplantation may be necessary in refractory cases.
Q: Should patients avoid eye procedures because of this risk?
A: No. LASIK, cataract surgery, and other eye procedures are among the safest and most effective in medicine. The outbreak is extremely rare. Patients should know the warning signs and seek immediate care if they develop post-procedure eye symptoms.
