2. Purpureocillium lilacinum

P. lilacinum is a hyaline mold that is ubiquitous in the environment, found in soil, decaying plant material, indoor air, and foods. It has also been detected as a contaminant in antiseptic skin products and lens-sterilizing solutions. Until recently, it was considered to belong to the genus Paecilomyces (previous name Paecilomyces lilacinus), but newer taxonomic studies have shown that it is genetically distinct.

The most frequent infection caused by P. lilacinum is keratitis in otherwise healthy hosts, usually following trauma, surgery, or prolonged contact lens use. The second most common category consists of cutaneous and subcutaneous infections, primarily in transplant recipients (solid organs, hematopoietic stem cells), while other important predisposing factors include primary or acquired immunodeficiency and surgery. P. lilacinum can also cause disseminated infections such as fungemia, endocarditis, peritonitis, osteomyelitis, as well as deep-seated or systemic infections. Other types of infections have also been reported, though less frequently.

Diagnosis is based on conventional mycological methods, PCR with ITS sequencing, and also MALDI-TOF MS, provided the database includes this species. Colonies grow fast on culture media and macroscopically appear light purple with a velvety texture on Sabouraud and Potato Dextrose Agar. The microscopic morphology is characterized by septate, hyaline hyphae and penicillus-like (brush-like) conidiogenous cells (phialides), branched in a manner reminiscent of Penicillium species, producing ovoid conidia in chains.

lilacinum strains exhibit high resistance to amphotericin B but are susceptible to azoles. According to the most recent guidelines (ECMM/ISHAM, 2021), the recommended first-line antifungal treatment is voriconazole, while second-line or salvage therapy includes either itraconazole, liposomal amphotericin B (L-AmB), or posaconazole.

In the present case, the patient received topical therapy with voriconazole eye drops (MIC 0.06 mg/L); however, due to unsatisfactory response, he ultimately underwent penetrating keratoplasty.

[Case editor: M. Drogari-Apiranthitou, Research Laboratory of Infectious Diseases, 4th Dept of Internal Medicine, National and Kapodistrian University of Athens]

References

Usuda D, Furukawa D, Imaizumi R, Ono R, Kaneoka Y, Nakajima E, et al. Purpureocillium lilacinum: A minireview. World J Clin Cases 2025. https://doi.org/ 10.12998/wjcc.v13.i29.108582.

Hoenigl M, Salmanton-García J, Walsh TJ, Nucci M, Neoh CF, Jenks JD, et al. Global guideline for the diagnosis and management of rare mould infections: An initiative of the European Confederation of Medical Mycology in cooperation with the International Society for Human and Animal Mycology and the American Society for Microbiology. Lancet Infect. Dis. 2021. https://doi.org/10.1016/S1473-3099(20)30784-2.

Skiada A, Pavleas I, Drogari-Apiranthitou M. Rare fungal infectious agents: a lurking enemy. F1000Res. 2017. https://doi.org/12688/f1000research.11124.1.

Luangsa-Ard J, Houbraken J, van Doorn T, et al.: Purpureocillium, a new genus for the medically important Paecilomyces lilacinus. FEMS Microbiol Lett. 2011. https://doi.org/10. 1111/j.1574-6968.2011.02322.x.

Almeida Oliveira M, Carmo A, Rosa A, Murta J. Posaconazole in the treatment of refractory Purpureocillium lilacinum (former Paecilomyces lilacinus) keratitis: the salvation when nothing works. BMJCaseRep.2019.. https://doi.org/10.1136/bcr-2018-228645.

Turner LD, Conrad D. Retrospective case-series of Paecilomyces lilacinus ocular mycoses in Queensland Australia. BMC Res Notes. 2015. https://doi.org/10.1186/s13104-015-1591-0

Todokoro D, Yamada N, Fukuchi M, Kishi S. Topical voriconazole therapy of Purpureocillium lilacinum keratitis that occurred in disposable soft contact lens wearers. Int Ophthalmol. 2014. https://doi.org/10.1007/s10792-014-9965-1.