Bilateral Prosthetic Knee Joint Infection Caused by Brucella melitensis: A Rare Case Report from Iran

Introduction: Brucella prosthetic joint infection is a rare condition. We report a case of bilateral prosthetic knee joint infection caused by Brucella melitensis, which was cured by prolonged antibiotic therapy without implant removal. Case Presentation: A 62-year-old woman was admitted to the Labbafinejad Hospital (Tehran, Iran), complaining of pain and swelling in her knee joints from two months ago. She was also suffering from intermittent fever and night sweats. She underwent bilateral total knee arthroplasty five years ago because of a severe degenerative joint disease. Agglutination tests (wright and 2-mercaptoethanol (2-ME)) were positive. Her knee joint fluid and blood cultures yielded B. melitensis. The polymerase chain reaction result from her knee joint fluid was positive for Brucella spp. The patient was cured after taking a combination of therapies with doxycycline, rifampin, and gentamicin. The prosthesis was retained due to the lack of loosening in radiography. Ten months after the treatment, the patient had no symptoms and could walk with no pain. Conclusions: Clinicians should consider brucellosis in the differential diagnosis of prosthetic joint infection in the endemic regions. They should also be aware that if patients have no sign of implant loosening, they can achieve favorable outcomes only by using antibiotics and with no need for implant removal.