Corynebacterium kroppenstedtii and granulomatous mastitis: The importance of recognizing when normal flora matters

Corynebacterium kroppenstedtii is a gram-positive, non-spore-forming, non-motile, lipophilic bacillus that belongs to the normal human skin flora. Granulomatous mastitis is a benign inflammatory breast condition with a complex diagnosis and treatment. Numerous studies have linked C. kroppenstedtii to granulomatous mastitis.

We conducted a clinical review on three patients with granulomatous mastitis caused by C. kroppenstedtii, identified by MALDI-TOF MS. We tested antibiotic susceptibility combining both disk diffusion and gradient diffusion assays, following EUCAST and CLSI guidelines.

In all three cases, C. kroppenstedtii was isolated in pure culture. Antibiotic susceptibility results were similar for most antibiotics, with variable susceptibility to clindamycin and tetracycline.

These three cases support the role of C. kroppenstedtii in the etiopathogenesis of granulomatous mastitis highlighting the importance of evaluating is isolation in patients with this disease.