An unusual case of prosthetic joint infection due to Arcanobacterium bernardiae

A 78-year-old man was admitted to the orthopaedic ward of the Centre Hospitalier Régional Universitaire for a haematoma of the left thigh which had appeared after a fall and 3 weeks of insidious pain. Medical history included a left total hip prosthesis because of a work accident 27 years previously. Examination revealed that his left hip prosthesis had worked loose, which was probably responsible for the fall. Laboratory data included a blood leukocyte count of 9.3610 l, with 73 % polymorphonuclear leukocytes, and a Creactive protein level of 18 mg l. The haematoma was drained surgically and the prosthesis was removed and replaced by a spacer. During the intervention, four biopsies (haematoma, muscle, femur and acetabulum) were performed. Gram stain of the haematoma and the femur biopsy smears showed Gram-positive bacilli. As the patient was apyretic, blood cultures were not performed. A combination of linezolid and cefotaxime was started until the microbiological results were available.