LAUSR

A 67-year-old woman without any particular medical/social history or prescriptions consulted us with a week-long fever and right frontal chest pain, where we observed an erythematous change (Picture A). She had untreated diabetes (hemoglobin A1c, 14.1%) on consultation and computed tomography (CT) revealed massive mediastinal abscess formation around her right sternoclavicular joint (Picture B-D). No other infectious foci were detected by the CT scan. Blood culturing detected Streptococcus agalactiae, and the patient underwent complete debridement under general anesthesia. S. agalactiae was isolated from the drained abscess as well. Her condition was ameliorated with six weeks of penicillin therapy. CT showed typical findings of sternoclavicular septic arthritis and a secondary mediastinal abscess, which was caused by Group B Streptococcus (GBS) in this case. Cases involving the sternoclavicular joint account for less than 1% of all cases of systemic suppurative arthritis (1). One significant risk factor for this rare entity is diabetes, as was seen in the patient (2). Notably, another patient with poorly controlled diabetes mellitus was reported to have developed GBS-induced mediastinal abscess (3). As risk factors other than diabetes, several host factors, including mucosal immunity as well as complex bacterial factors are known to be associated with GBS infection (4). More attention should be paid to this potentially fatal pathogen.