Mycobacterium fortuitum (M. fortuitum), a rapidly growing nontuberculous mycobacterium (NTM), is an emerging pathogen in trauma-associated skin and soft tissue infections (SSTIs). Pediatric NTM infections are rare and often misdiagnosed due to nonspecific clinical manifestations mimicking those of pyogenic bacterial infections. We report the first pediatric case of refractory M. fortuitum SSTIs following a dog bite in an 8-year-old child, highlighting diagnostic and management challenges. An 8-year-old child presented with SSTIs on the anteromedial right thigh following a dog bite, which remained refractory to a 2-week course of empiric β-lactam therapy. Histopathology revealed nodular granulomatous inflammation with epithelioid cells and purulent necrosis, and acid-fast bacilli were identified via Ziehl-Neelsen staining. Targeted next-generation sequencing (tNGS) rapidly identified M. fortuitum within 48 h, with confirmation by automated liquid culture (7-day growth) and targeted PCR. A multidisciplinary approach integrating broth microdilution-guided combination therapy (amikacin 15 mg/kg IV q48h, linezolid 10 mg/kg PO q12h, and doxycycline 3 mg/kg PO q12h) with weekly or biweekly surgical debridement achieved complete resolution of the cutaneous lesions. No relapse was noted during 6 months of follow-up, with regular clinical and laboratory evaluations. This case underscores three critical findings: (1) NTM infections warrant inclusion in the differential diagnosis of animal bite wounds refractory to β-lactams; (2) tNGS facilitates rapid rare pathogen identification, enabling target-directed therapy within 48 h; (3) The multidisciplinary team is imperative to coordinate combined antimicrobial and surgical interventions. Enhanced awareness of the zoonotic potential of NTM is recommended for bite wound management, particularly in pediatric patients.
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