A Case of a Young Patient With Necrotizing Soft Tissue Infection Caused by Community-Acquired Methicillin-Resistant Staphylococcus aureus

Necrotizing soft tissue infections (NSTIs) are rare but life-threatening conditions characterized by rapidly progressive tissue destruction. Although methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) is a well-known pathogen, community-acquired MRSA (CA-MRSA) is an uncommon cause of NSTI, especially in otherwise healthy pediatric patients. We report the case of a previously healthy 13-year-old boy who developed NSTI of the lower extremity after sustaining a trivial insect bite. On admission, he presented with rapidly progressive swelling, erythema, and severe pain out of proportion to physical findings. Computed tomography revealed fat stranding and thickening of the superficial fascia, and the finger test was positive. Emergency debridement revealed a necrotic area of subcutaneous fat and fascia measuring approximately 15 × 8 cm, and MRSA was identified in swab cultures. The patient required re-debridement, followed by negative pressure wound therapy (NPWT). A split-thickness skin graft was performed on day 21, after confirming negative wound cultures, with no graft-related complications. The patient was discharged in good condition after 62 days of hospitalization. This case illustrates that CA-MRSA, though rarely causing NSTI, can lead to severe, rapidly progressive infections even in healthy children. Clinicians should maintain vigilance, as even minor injuries may serve as portals of entry. Early recognition, timely surgical debridement, and empiric MRSA coverage are critical to optimizing outcomes, and this case contributes to the limited literature on pediatric CA-MRSA NSTI in Japan.