Trichosporon asahii subcutaneous soft tissue infection after trauma surgery in an immunocompetent patient: a case report.

Trichosporon asahii (T. asahii) is a rare non-Candida basidiomycetous yeast. It commonly causes invasive infections in immunocompromised individuals, while severe subcutaneous soft tissue infections in immunocompetent patients are extremely uncommon.Here, we report a 67-year-old immunocompetent female who developed secondary T. asahii infection after debridement and suturing for left lower leg trauma, presenting with local skin necrosis, purulent exudation and undermining abscesses, with normal systemic inflammatory markers. The pathogen was confirmed as T. asahii via Vitek Compact system, MALDI-TOF mass spectrometry and next-generation sequencing (NGS). Antifungal susceptibility testing verified susceptibility to voriconazole. The patient achieved marked improvement after 3 weeks of treatment with surgical debridement, vacuum sealing drainage (VSD) and voriconazole. Local infection was controlled and the wound began to heal, and antifungal drugs were then withdrawn. This case highlights that T. asahii infection should be suspected in refractory post-traumatic soft tissue infections in immunocompetent patients. The discordance between severe local lesions and minimal systemic inflammation serves as a key clinical clue. Early etiological diagnosis, surgical intervention combined with susceptible antifungal agents are critical for improving prognosis.