A neutropenic leukaemic patient receiving voriconazole prophylaxis after allogeneic transplant develops tender erythematous papules with central necrosis on the trunk and persistent fever. Blood cultures turn positive with septate hyphae. Serum beta-D-glucan is elevated but galactomannan index remains below the cut-off. Which property best explains these findings?

• A Unlike Aspergillus fumigatus, it can be recovered from blood cultures ✓
• B It shares the galactomannan antigen with Aspergillus species
• C It is uniformly resistant to echinocandins but susceptible to flucytosine
• D Its conidia germinate only at temperatures above 40 degrees Celsius

Explanation

Fusarium species cause disseminated infection in profoundly neutropenic patients, characterised by necrotic skin lesions and fungaemia. Unlike Aspergillus, Fusarium produces adventitious unicellular spores in vivo that allow culture positivity of blood in a substantial proportion of cases, making blood culture diagnostically useful. Fusarium does produce some cross-reactive galactomannan but levels are often low or negative, which fits this case. It is relatively resistant to amphotericin A and azoles, so breakthrough despite voriconazole is typical.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.