Expander or Implant? Mycobacterium Fortuitum Infection After Breast Reconstruction: Case Report

Infections associated with breast implants represent an important postoperative complication. Although bacterial infections caused by Gram-positive cocci are the most frequent causes of surgical site infections (SSIs), rapidly growing mycobacteria such as Mycobacterium fortuitum have been increasingly identified. M. fortuitum is a rapidly growing mycobacterium capable of forming biofilm and is resistant to usual antimicrobial regimens, which makes clinical management difficult. Early suspicion and diagnosis are fundamental to avoid therapeutic failures and unfavorable outcomes. This work aims to report a case of SSI caused by Mycobacterium fortuitum in a breast implant, addressing clinical, diagnostic, and therapeutic aspects. This is a prospective and descriptive case report prepared through medical record review. A female patient, 63 years old, with a diagnosis of ductal carcinoma in situ in the right breast treated surgically in 2014. In 2024, she presented recurrence of the neoplastic condition and underwent right mastectomy with insertion of a tissue expander for subsequent insertion of an implant in a second stage. In 2025, the patient underwent delayed breast reconstruction with exchange of expander for definitive breast implant. Intraoperatively, it was described that the expander had leakage of the previously injected saline. After 26 days of the procedure, the patient developed local erythema at the surgical wound, pain, chills, and fever. Breast ultrasound showed collections with estimated volumes of 18.5 mL and 4.2 mL in the subcutaneous plane adjacent to the breast implant. Aspiration of the fluid was performed and the material sent for analysis; aerobic culture showed growth of Mycobacterium fortuitum after approximately three days. Treatment was started with clarithromycin, levofloxacin, and amikacin. During hospitalization, surgical removal of the implant with cavity cleaning was performed. The patient progressed well with improvement of the infectious condition and was discharged to complete the therapeutic regimen at home. Infections by M. fortuitum in breast implants are a rare but relevant condition that should be considered in infections with a protracted course or refractory to conventional treatment. Isolation of the agent and a combined approach with implant removal and prolonged antibiotic therapy are fundamental for therapeutic success.