Recurrent Breast Abscesses due to Corynebacterium kroppenstedtii, a Human Pathogen Uncommon in Caucasian Women

Background. Corynebacterium kroppenstedtii (Ck) was first described in 1998 from human sputum. Contrary to what is observed in ethnic groups such as Maori, Ck is rarely isolated from breast abscesses and granulomatous mastitis in Caucasian women. Case Presentation. We herein report a case of recurrent breast abscesses in a 46-year-old Caucasian woman. Conclusion. In the case of recurrent breast abscesses, even in Caucasian women, the possible involvement of Ck should be investigated. The current lack of such investigations, probably due to the difficulty to detect Ck, may cause the underestimation of such an aetiology. 1. Background The majority of corynebacteria are normal skin flora. It usually is difficult to distinguish between infection, colonization, and contamination by isolated bacteria. By contrast, our Corynebacterium kroppenstedtii (Ck) strain was isolated as monomicrobial culture. Ck is a lipophilic Corynebacterium. Its first isolation was described in 1998 from human sputum [1]. It has also been found in association with inflammatory breast diseases [2]. In 2003, Taylor et al. observed that the incidence of corynebacteria-associated inflammatory breast diseases was much higher in Maori women than women of European descent in whom this type of infection is rare [2]. This species of Corynebacterium does not contain mycolic acids and needs lipids for its growth. This is why, the mammary areas, rich in lipids, are favourable to its development and its proliferation. This physiological feature explains the uncommon tissue tropism of this rare bacterium and its ability to efficiently grow in breasts. 2. Case Presentation A 46-year-old Caucasian woman presented recurrent breast abscesses. The patient’s medical history revealed that she was a nonsmoker and did not take any kind of medication and she did not have a recent history of breast-feeding. Before symptoms began, there was no sign of breast lesion. Seven months earlier, the first symptom (Month 0 = M0) was a brutal onset of pain in the left breast, with no fever and no other symptom. One month later (M1), the first echography and mammography showed a left external para-areolar mass measuring 24？mm × 16？mm. This hyperechoic mass was surrounded with an hypoechoic and hypervascular halo. At that time, the patient was treated with oral amoxicillin-clavulanic acid 3？g–0.375？g three times a day for 8 days. The patient showed neither clinical nor radiological improvement. After the first course of treatment, the patient was sampled. Cytological and histological analyses of the fine needle