Detection of Finegoldia magna in Cyst Secretions from a Non-Lutating Female Breast: A Case Report

Abstract: Finegoldia magna is a Gram-positive, obligately anaerobic coccus, often colonizing the skin and mucous membranes, capable of causing multi-site and mixed infections. This study retrospectively analyzed the clinical data and microbiological examination results of a case where F. magna was cultured from purulent secretions of a breast cyst in a non-lactating female, combined with a review of relevant domestic and international literature. In vitro drug susceptibility testing showed that the strain was susceptible to penicillin, ampicillin, ceftriaxone, and imipenem, but resistant to clindamycin. The empyema cavity was irrigated with gentamicin saline, and local dressing changes were performed, leading to good wound healing and discharge. This case suggests that clinicians should pay attention to the possibility of anaerobic bacterial infections after breast surgery, especially when routine bacterial cultures are negative, necessitating timely anaerobic culture. Combined with mass spectrometry identification and drug susceptibility test results, this approach guides precise treatment. Keywords: non-lactating female, breast cyst, Finegoldia magna , anaerobic bacteria, antibiotic susceptibility testing