We present the first published case of Coxiella burnetii prosthetic joint infection. Diagnosis was established with PCR and culture of periprosthetic tissue and synovial fluid (and serology). A novel PCR assay is described herein. Q fever should be considered in patients with prosthetic joint infection without an identified pathogen. J oint replacement is a life-enhancing procedure performed on hundreds of thousands of patients in the United States each year. While prosthetic joint infection (PJI) occurs in only approximately 2% of patients following knee arthroplasty (1), it is a devastating complication. Accurate microbiologic diagnosis of PJI is important for directing appropriate management. There is no identified pathogen in approximately 7% of PJI cases, frequently as a result of antecedent antimicrobial therapy, but occasionally due to an inability to detect a pathogen by standard laboratory methods (2). Coxiella burnetii is not an organism that would traditionally be considered in a case of culture-negative PJI. We describe here the first published case of PJI caused by C. burnetii.The causative agent of the zoonosis Q fever, C. burnetii, is a small, obligate intracellular Gram-negative bacterium. Acute and chronic types of Q fever are classically diagnosed based on compatible clinical illnesses, supported by serologic results (3). Isolation of C. burnetii in cell culture is laborious, requires specially trained staff, and poses a safety risk to staff (4, 5), confining C. burnetii culture to a small number of research and public health laboratories and limiting medical practitioners' access to this technique for diagnostics.Q fever PCR offers a safe alternative to culture for direct detection of C. burnetii in clinical specimens. The majority of PCR assays for C. burnetii have targeted the insertion sequence element IS1111 (6-10). As a mobile genetic element, there is the potential for IS1111 to move from one organism type to another, theoretically resulting in loss of specificity (11). The diagnosis of C. burnetii PJI in the case reported here was made using a novel real-time PCR assay (described below) targeting the single-copy housekeeping gene target, shikimate dehydrogenase (aroE) of C. burnetii.
CASE REPORTA 56-year-old male presented to our institution with new increasing right knee pain and swelling around a previously revised total knee arthroplasty (TKA).He first developed right knee pain after patellectomy for a comminuted patellar fracture at 27 years of age. He underwent repeated arthroscopies without improvement; right TKA was performed at age 44. This was complicated by early postoperative deep vein thrombosis (DVT). He developed increasing right knee pain, swelling, and stiffness approximately 12 weeks after arthroplasty. Subcutaneous corticosteroid and lidocaine injections were administered around the branches of the saphenous nerve on a monthly basis for presumed neuropathic pain.At the age of 53, he presented to our facility with a 5-day history of general malaise, mild nonproductive c...