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Phaeohyphomycosis due to Nigrograna chromolaenae in a cardiac transplant patient

Summary

A 71-year-old heart transplant patient developed a slowly growing bump on his finger caused by a rare fungus called Nigrograna chromolaenae. Doctors initially tried common antifungal medications that didn’t work well, but the patient improved significantly when switched to posaconazole treatment. This is the first documented case of this particular fungus infecting a human, highlighting the importance of accurately identifying fungi to choose the right treatment.

Background

Phaeohyphomycoses are rare fungal infections caused by dematiaceous fungi, typically associated with tropical regions and immunocompromised patients such as transplant recipients. Nigrograna species have recently emerged as a cause of black grain eumycetoma. Disease associated with Nigrograna chromolaenae has not previously been reported in human hosts.

Objective

To report the first confirmed case of Nigrograna chromolaenae infection in a cardiac transplant recipient and describe the clinical presentation, identification, and treatment of this previously unreported fungal infection.

Results

The isolate was initially identified as Biatriospora mackinnonii but re-identified as Nigrograna chromolaenae through phylogenetic analysis. The patient showed poor response to itraconazole and voriconazole but improved with posaconazole therapy over 4 months, achieving complete healing of the lesion. Antifungal susceptibility testing showed low MICs for amphotericin B, itraconazole, and posaconazole.

Conclusion

This is the first reported case of Nigrograna chromolaenae cutaneous infection in a human host and in a cardiac transplant recipient. Accurate species-level identification through molecular methods and antifungal susceptibility testing is essential for optimal management of phaeohyphomycosis in immunocompromised patients. Posaconazole proved effective for treatment of this infection.
  • Published in:Medical Mycology Case Reports,
  • Study Type:Case Report,
  • Source: PMID: 40838112, DOI: 10.1016/j.mmcr.2025.100722
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