MRSA in the bursa: an unusual complication of MRSA bacteremia causing bilateral acromioclavicular septic arthritis

Background. Bacteraemia is known to cause serious complications including metastatic infections such as infective endocarditis, vertebral osteomyelitis, iliopsosas abscesses and septic arthritis. Bilateral septic arthritis, however, is a rare medical emergency with limited previous reports. Staphylococcus species are the most common organisms identified as a result of suspected haematogenous spread from bacteraemia, direct inoculation or translocation from adjacent tissues. While unilateral septic arthritis due to intravenous drug use is a common phenomenon warranting prompt treatment to preserve mobility, function and quality of life, cases of bilateral infections are exceedingly rare. Furthermore, infections involving the acromioclavicular joint are not commonly documented in the literature. Case Presentation. We present a case of a 41-year-old female with a history of intravenous drug use who presented with low back pain and was found to have methicillin-resistant Staphylococcus aureus bacteraemia that was complicated with metastatic infections causing bilateral acromioclavicular joint septic arthritis. Conclusions. Metastatic infections from bacteraemia are serious complications that can lead to septic arthritis. Though septic arthritis is best known in previous case reports to present as a unilateral infection, rare cases of bilateral involvement warrant further consideration. A thorough history and physical examination evaluating all joints can identify such atypical presentations. Septic arthritis remains a medical emergency, and it is imperative that clinicians recognize unusual presentations to avoid delays in treatment that can lead to detrimental impacts to quality of life.