An Unusual Case of Septic Arthritis: Prevotella oralis and Calcium Pyrophosphate DiseaseRuisi, Phillip DO; Ruisi, Michael MD; Zohrabian, Vahe Michael MD; Epstein, Marcia MDInfectious Diseases in Clinical Practice: January 2012 - Volume 20 - Issue 1 - p 77–78 doi: 10.1097/IPC.0b013e3182152b91 Case Reports Abstract Author Information We present the case of a 91-year-old woman who developed septic arthritis of her knee after undergoing a dental extraction without antibiotic prophylaxis. Arthrocentesis of the left knee resulted in the drainage of purulent fluid and a few calcium pyrophosphate crystals. Synovial culture revealed Prevotella oralis. The relationship between septic arthritis and crystalloid arthropathy is not entirely certain, and in our case, it becomes difficult to assess which was present initially. Crystal arthritis may be a predisposition to a joint space infection, and in recent studies, an unprecedented high rate of gouty arthritis has been reported among a series of patients with septic arthritis of the ankle. This case report underscores the importance of routine synovial fluid analysis and culture in diagnosing joint pathology and supports a role for antibiotic prophylaxis in patients with possible nidi of infection, that is, crystal arthropathies, undergoing invasive procedures. From the North Shore University Hospital, Manhasset, NY. Correspondence to: Phillip Ruisi, DO, 2925 200th St, Bayside, NY 11360. E-mail: email@example.com. All authors participated in the writing of this article. The authors have no funding or conflicts of interest to disclose. © 2012 Lippincott Williams & Wilkins, Inc.