Closing the Brief Case: Encephalitis in a West Texas Woman

ANSWERS TO SELF-ASSESSMENT QUESTIONS

• 1.Which of the following fungi predominantly produce arthroconidia?

  1. Bipolaris sp.

  2. Cladosporium sp.

  3. Neoscytalidium sp.

  4. Alternaria sp.

Answer: c. All of the fungi listed are dematiaceous molds. Bipolaris sp. have oval-to-cylindrical, 3 to 6-celled conidia, and Cladosporium sp. conidia are generally in chains or branches. Alternaria sp. is named for the alternating divisions between the cells within the conidia. The only dematiaceous mold included in this list that produces arthroconidia is Neoscytalidium sp.

• 2.Which of the following fungi exhibit characteristic disjunctor cells between arthroconidia?

  1. Coccidioides sp.

  2. Neoscytalidium sp.

  3. Geotrichum sp.

  4. Histoplasma sp.

Answer: a. Coccidioides, Neoscytalidium, and Geotrichum all have a predominance of arthroconidia, although Coccidioides is the only species listed that elaborates disjunctor cells. Coccidioides sp., a dimorphic mold, has barrel-shaped arthrocondia during its mold phase that typically retain the lactophenol cotton blue stain, alternating with poorly staining, small disjunctor cells. Histoplasma capsulatum is also dimorphic like Coccidioides sp. but elaborate a mixture of microconidia and characteristic tuberculate macroconidia in their mold phase instead of arthroconidia. In contrast, Geotrichum is not dimorphic and produces arthroconidia without disjunctor cells.

• 3.Which of the following therapies might be used to treat phaeohyphomycosis?

  1. Voriconazole

  2. Micafungin

  3. Fluconazole

  4. Nystatin

Answer: a. Phaeohyphomycosis is extremely difficult to manage and generally requires surgical debridement; however, antifungal therapy, including broad spectrum azoles, such as voriconazole, are often used. Micafungin best treats invasive Candida infections; fluconazole can treat some Candida infections, cryptococcal infections, or coccidioidomycosis; and nystatin is a topical antifungal.

TAKE-HOME POINTS

• Young molds may not have fully developed characteristic pigments or classic diagnostic features.

• Cooperative review with multiple experienced technologists and/or a clinical microbiologist for atypical fungal morphology is advised, and molecular identification may be considered, especially in high-consequence infections.

• Neoscytalidium sp. is an unconventional dematiaceous mold in that its primary means of reproduction in the environment utilizes arthroconidia.

• The treatment implications for phaeohyphomycosis are vastly different compared to those of coccidioidomycosis.