Purpureocillium lilacinum Keratitis Outbreak Linked to Laser Vision Correction Procedures
Three cases of severe fungal keratitis caused by Purpureocillium lilacinum were reported in New York in late 2024 following outpatient surface ablation laser vision correction (LVC) procedures, according to a Centers for Disease Control and Prevention (CDC) alert.
What Caused the 2024 Outbreak of Purpureocillium lilacinum Keratitis?
The CDC identified P. lilacinum, a filamentous fungus formerly Paecilomyces lilacinum, as the pathogen responsible for the 2024 outbreak. All three patients had undergone surface ablation procedures using an epikeratome. Environmental testing detected P. lilacinum DNA in the epikeratome suction tubing, suggesting contaminated equipment as a transmission vector. The clinic also used cool mist humidifiers, which have been previously implicated in Mycobacterium chelonae ocular infections.
Why Is Purpureocillium lilacinum a Concern for Ophthalmic Surgeons?
P. lilacinum is an environmental mold. While rare in immunocompetent individuals, it can cause severe, progressive keratitis after ocular trauma, contact lens wear, or ophthalmic surgery. The 2024 outbreak underscores its potential to cause deep, treatment-resistant infections. P. lilacinum is less susceptible to polyene antifungal agents, and treatment with amphotericin B and natamycin has been linked to poorer clinical outcomes. Aggressive treatment with off-label use of azole antifungals topically (voriconazole), intrastromally (voriconazole) and orally (posaconazole) is recommended.
How Common Are Infections After Laser Vision Correction?
Infections following laser vision correction remain a rare but potentially devastating occurrence. Estimates suggest an approximate incidence rate of one in 5,000 LASIK procedures and one in 1,000 surface ablation procedures. The higher rate for surface ablation is attributed to the breach of the corneal epithelial barrier and the use of a therapeutic contact lens. Since around 2000, a shift in the organisms recovered in LVC-associated infections was observed from common pathogens to less common, “atypical” pathogens, including species of nontuberculous mycobacteria.
What Preventive Measures Are Recommended for Refractive Surgery Teams?
Refractive surgical teams should be familiar with and apply strict aseptic practices in ophthalmic surgeries. Current health care engineering guidelines specify that steam humidification should be used. Terrence P. O’Brien, MD, a professor of ophthalmology and Charlotte Breyer Rodgers Distinguished Chair at Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, notes that lessons learned dating from the inception of laser keratorefractive procedures emphasize “prior proper preparation preventing poor performance.”
What Are the Long-Term Implications of This Outbreak?
While P. lilacinum has been a rarer cause of fungal keratitis compared with other filamentous fungi, recovery rates from commercial microbiological laboratories have demonstrated recently increasing detection of P. lilacinum from 2019 to 2025. This observed increase may be due to the intentional introduction of P. lilacinum as a bionematocide in agricultural control of plant parasites. P. lilacinum should be considered as a potential cause of severe, drug-resistant keratitis with LVC procedures.
O’Brien, MD, University of Miami Miller School of Medicine.