Evaluation of Musculoskeletal and Pulmonary Bacterial Infections With [124I]FIAU PET/CT.

PURPOSE: Imaging is limited in the evaluation of bacterial infection. Direct imaging of in situ bacteria holds promise for noninvasive diagnosis. We investigated the ability of a bacterial thymidine kinase inhibitor ([124I]FIAU) to image pulmonary and musculoskeletal infections. METHODS: Thirty-three patients were prospectively accrued: 16 with suspected musculoskeletal infection, 14 with suspected pulmonary infection, and 3 with known rheumatoid arthritis without infection. Thirty-one patients were imaged with [124I]FIAU PET/CT and 28 with [18F]FDG PET/CT. Patient histories were reviewed by an experienced clinician with subspecialty training in infectious diseases and were determined to be positive, equivocal, or negative for infection. RESULTS: Sensitivity, specificity, positive-predictive value, negative-predictive value, and accuracy of [124I]FIAU PET/CT for diagnosing infection were estimated as 7.7% to 25.0%, 0.0%, 50%, 0.0%, and 20.0% to 71.4% for musculoskeletal infections and incalculable-100.0%, 51.7% to 72.7%, 0.0% to 50.0%, 100.0%, and 57.1% to 78.6% for pulmonary infections, respectively. The parameters for [18F]FDG PET/CT were 75.0% to 92.3%, 0.0%, 23.1% to 92.3%, 0.0%, and 21.4% to 85.7%, respectively, for musculoskeletal infections and incalculable to 100.0%, 0.0%, 0.0% to 18.2%, incalculable, and 0.0% to 18.2% for pulmonary infections, respectively. CONCLUSIONS: The high number of patients with equivocal clinical findings prevented definitive conclusions from being made regarding the diagnostic efficacy of [124I]FIAU. Future studies using microbiology to rigorously define infection in patients and PET radiotracers optimized for image quality are needed.

Reinfected revised TKA resolves with an aggressive protocol and antibiotic infusion.

BACKGROUND: Revision of failed two-stage revision TKA for infection is challenging, and amputation often is the only alternative. QUESTIONS/PURPOSES: We asked whether reinfection after two-stage revision for infection could be controlled with an aggressive revision protocol and intraarticular antibiotic infusion. METHODS: We retrospectively reviewed 18 patients (12 women, six men) who underwent revision for failed reimplantation between January 1999 and January 2008. Mean time from revision for infection to rerevision for reinfection was 5 months (range, 1-18 months). All knees were treated with an individualized protocol that included aggressive exposure, extensive débridement, uncemented components, closure with muscle flaps (seven knees) and other plastic surgery procedures (three knees), and direct antibiotic infusion through Hickman catheters for 6 weeks. Ten knees had one-stage revision; five had débridement, cement spacer, and revision surgery 3 to 4 months later; and three had extensive soft tissue reconstruction before revision surgery. The minimum followup was 2.3 years (mean, 6.1 years; range, 2.3-12.0 years). RESULTS: The mean Knee Society scores improved from 33 preoperatively to 76. Seventeen of the 18 had control of infection and achieved durable fixation and a closed wound. One patient had recurrent infection 13 months after one-stage revision, was revised, and remained asymptomatic 28 months postoperatively after redébridement and vancomycin infusion for 6 weeks. In one patient, soft tissue closure was not obtained and the patient required amputation. CONCLUSIONS: Extensile exposure, débridement, and soft tissue flaps for closure combined with uncemented fixation of revision implants and antibiotic infusion into the knee controlled reinfection after revision TKA.

Methicillin-resistant Staphylococcus aureus in TKA treated with revision and direct intra-articular antibiotic infusion.

BACKGROUND: Resistant organisms are difficult to eradicate in infected total knee arthroplasty. While most surgeons use antibiotic-impregnated cement in these revisions, the delivery of the drug in adequate doses is limited in penetration and duration. Direct infusion is an alternate technique. QUESTIONS/PURPOSES: We asked whether single-stage revision and direct antibiotic infusion for infected TKA would control infection in patients with methicillin-resistant Staphylococcus aureus (MRSA) infections. METHODS: We retrospectively reviewed 18 patients (18 knees) with MRSA with one-stage revision protocol that included débridement, uncemented revision of total knee components, and intraarticular infusion of 500 mg vancomycin via Hickman catheter once or twice daily for 6 weeks; we used no intravenous antibiotics after the first 24 hours. We monitored serum vancomycin levels to maintain levels between 3 and 10 microg/mL. Minimum followup was 27 months (range, 27­75 months). Mean followup was 62 months, (range, 27­96 months). RESULTS: Infection was controlled at last followup in all but one patient with a recurrence of the MRSA. The patient was reoperated at 5 months; a necrotic bone fragment was removed, the knee was débrided and revised, and the antibiotic infusion protocol readministered. The patient remained free of infection 42 months postoperatively. At 2-year followup, the mean Knee Society score was 83. We observed no radiographic evidence of implant migration. CONCLUSIONS: One-stage revision and 6 weeks of intraarticular vancomycin administration controlled infection in MRSA infected TKA with no apparent complications. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.