Management of Finegoldia magna-associated non-puerperal breast abscess in an adolescent: Integration of surgical source control and targeted antimicrobial therapy.

Finegoldia magna is an opportunistic anaerobic pathogen rarely causing non-puerperal breast abscess (NPBA) in adolescents. Its biofilm-forming capacity often complicates standard treatments. We report a 17-year-old female who presented with NPBA following influenza A and the rupture of an epidermal cyst. Anaerobic culture identified F. magna alongside Staphylococcus simulans. Guided by the patient's penicillin allergy and anaerobic resistance trends, systemic cefmetazole was administered. Concurrently, ultrasound-guided mechanical cavity debridement was performed, followed by percutaneous indwelling catheter placement for continuous intralesional metronidazole irrigation. This integrated approach achieved rapid infection eradication, normalized inflammatory markers, and preserved breast aesthetics without recurrence. For adolescent NPBA associated with biofilm-forming anaerobes, integrating minimally invasive, catheter-based surgical source control with targeted antimicrobial therapy ensures optimal clinical and cosmetic outcomes.