Answer to April 2018 Photo Quiz

Answer: Saksenaea oblongispora. The fungal cultures grew a mold, identified as Saksenaea oblongispora (Fungus Testing Laboratory, University of Texas Health Sciences Center, San Antonio, TX). Antifungal susceptibility testing was attempted but was unsuccessful. The patient completed 16 weeks of oral therapy with posaconazole. She had excellent healing and no evidence of recurrence or visual impairment at follow-up 4 months after completing therapy.

The genus Saksenaea, within the order Mucorales, includes environmental molds found in soil worldwide. This organism has broad, thin-walled hyphae with infrequent septation. Formerly, it was considered to consist of only a single species, S. vasiformis. Most published reports reflect this nomenclature. Recently, Alvarez and colleagues (1) used molecular methods to classify the S. vasiformis complex into two new species, S. erythrospora and S. oblongispora.

Identification on Sabouraud's agar is difficult by standard laboratory techniques, as sporulation rarely occurs. The characteristic appearance includes flask-shaped sporangia and dark-pigmented rhizoids, as were observed in our case. The preferred laboratory methods include the additional use of Czapek Dox agar or nutritionally deficient medium allowing for demonstration of fruiting structures that may require extended incubation (2). Optimal growth occurs at 25°C. Sequencing or nucleic acid amplification with specific DNA probes offers an accurate identification (1, 3). The isolate from our patient was slow growing, had white colonies without reverse pigmentation, and was identified as S. oblongispora by nucleic acid sequencing.

Infections due to Saksenaea spp. most commonly present as skin and soft tissue disease in the setting of trauma. Unlike for other agents of mucormycosis, Saksenaea sp. infections have been reported to occur in immunocompetent hosts (3, 4). Dacryocystitis associated with Saksenaea spp. has not previously been reported in the English language literature. Our patient did not have immunosuppression, sinus disease, trauma, or other known predisposing factors. One possible source was her eye makeup, but this was not available for culture.

Saksenaea spp. are a rare cause of mucormycosis and are capable of causing serious infections in immunocompetent as well as immunocompromised persons. Identification of the organism is difficult and may require molecular techniques. Prompt evaluation and diagnosis are necessary, as infections with Saksenaea spp. can be locally destructive, with extension into the skin, resulting in scarring, sinus tract formation, and dissemination into the bloodstream. Surgical biopsy and fungal culture, as in this case, are often required for diagnosis.

See https://doi.org/10.1128/JCM.00463-16 in this issue for photo quiz case presentation.