Diagnostic and therapeutic challenges of treating opportunistic fungal cellulitis: a case series

BACKGROUND: Cellulitis is an infection most commonly caused by bacteria and successfully treated with antibiotics. However, certain patient populations, especially the immunocompromised, are at risk for fungal cellulitis, which can be misidentified as bacterial cellulitis and contribute to significant morbidity and mortality. CASE PRESENTATIONS: We describe three cases of opportunistic fungal cellulitis in immunosuppressed patients that were initially mistaken for bacterial infections refractory to antibiotic therapy. However, atypical features of cellulitis ultimately prompted further diagnostics to identify fungal cellulitis and allow initiation of appropriate antifungals. We discuss: (1) a 52-year-old male immunosuppressed hematopoietic cell transplant recipient with Fusarium solani cellulitis on his right lower extremity that was treated with amphotericin B and voriconazole with full resolution of the cellulitis; (2) a 70-year-old male lung transplant recipient with Fusarium solani cellulitis on his left lower extremity that ultimately progressed despite antifungals; and (3) a 68-year-old male with a history of kidney transplantation with suspected Purpureocillium lilacinum cellulitis on his left lower extremity ultimately treated with posaconazole with resolution of the skin lesions. CONCLUSIONS: Fusarium solani and Purpureocillium lilacinum are important pathogens causing opportunistic fungal cellulitis. These cases remind providers to be vigilant for fungal cellulitis when skin and soft tissue infection does not adequately respond to antibiotics and atypical features of cellulitis are present.