Case Report Brucella Periprosthetic Joint Infection Involving Bilateral Knees with Negative Synovial Fluid Alpha-Defensin Abdullah Balkhair , 1 Sultan Al Maskari, 2 Shadin Ibrahim, 1 Ibrahim Al Busaidi , 1 Mohammed Al Amin, 1 and Hashim Ba Taher 1 1 Department of Medicine, Infectious Diseases Unit, Sultan Qaboos University Hospital, P.O. Box. 35, Al koudh. 123, Muscat, Oman 2 Department of Surgery, Orthopaedics Unit, Sultan Qaboos University Hospital, P.O. Box. 35, Al koudh. 123, Muscat, Oman Correspondence should be addressed to Abdullah Balkhair; balkhair2020@gmail.com Received 3 May 2019; Accepted 17 June 2019; Published 14 July 2019 Academic Editor: Gloria Taliani Copyright © 2019 Abdullah Balkhair et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Periprosthetic joint infection (PJI) due to Brucella is uncommon despite relatively high endemicity of human brucellosis and its osteoarticular predilection. We report a case of a 57-year-old woman with bacteraemic brucellosis complicated by Brucella periprosthetic infection of both knee joints occurring a decade after bilateral knee arthroplasty and associated with a negative synovial fluid alpha-defensin test. e patient was successfully treated with anti-Brucella therapy alone and without surgical revision, resulting in clinical and microbiological cure. We propose that Brucella should be considered as a possible cause of prosthetic joint infection in the appropriate clinical and epidemiological settings. A negative synovial fluid alpha-defensin (Synovasure AD test) should not be used as a rule-out test for Brucella PJI. Brucella PJI without radiological loosening may be treated conservatively and solely with antimicrobial therapy. 1. Introduction Brucellosis is a zoonotic infection with approximately 500,000 cases reported annually in disease-endemic regions [1]. Brucellosis is caused by any of the four pathogenic species to humans, namely, Brucellaabortus, B.melitensis, B. suis, and B. canis. Although brucellosis is believed to be a significant livestock infection in Oman, it has not been studied extensively [2, 3]. Ingestion of unpasteurized milk or milk products is believed to be the commonest route of transmission in Oman [4]. A retrospective analysis of human brucellosis in Oman between 1995 and 2012 identified 2737 human cases of brucellosis with 96.7% of these in the southern part of Oman (Dhofar) [4]. Brucellosis is char- acterized by its myriad presentations and multisystemic nature with osteoarticular involvement being one of the most frequent manifestations of this disease [5]. Total knee arthroplasty is one of the most common procedures in orthopaedic surgery including in areas where brucellosis is endemic [6] with periprosthetic joint infection (PJI), one of the most serious complications of prosthetic joint implantation [7]. Periprosthetic joint infections may account for up to 25% of revision total knee arthroplasties [8]. Periprosthetic joint infection due to Brucella is in- frequent. In a recent review of published literature of Brucella PJIs, thirty cases were identified of which nineteen cases were prosthetic knee infections including four cases with Brucella infection of bilateral knee prostheses [9]. e median time from implantation of the prosthesis to the diagnosis of PJI was two years in this same cohort [9]. e pathogenesis of Brucella PJI is believed to be due to he- matogenous seeding of the arthroplasty components com- plicating bacteraemic brucellosis [10]. Diagnosis of periprosthetic joint infection—albeit Bru- cella PJI—can be challenging. However, several publications exist to guide diagnosis of PJI in general, and these include guidelines by the Musculoskeletal Infection Society [11], the Hindawi Case Reports in Infectious Diseases Volume 2019, Article ID 9423946, 3 pages https://doi.org/10.1155/2019/9423946