Authors: A. TRAMPUZ, A.D. HANSSEN, D.R. OSMON, K.E. PIPER, M.S. ROUSE, J.M. STECKELBERG, R. PATEL.
Title: The Role of Preoperative Antimicrobial Therapy on Culture Sensitivity of Joint Fluid, Periprosthetic Tissue and Explant Sonicate in the Diagnosis of Prosthetic Joint Infection
Addresses: Mayo Clinic, Rochester, MN
Purpose: Treatment with antimicrobial agents for suspected prosthetic joint infection (PJI ) prior to specimen collection may reduce their culture sensitivity. We analysed the possible role of preoperative antimicrobial therapy for PJI on the sensitivity of joint fluid, periprosthetic tissue and explant sonicate cultures from patients undergoing hip or knee replacement.
Methods: PJI was defined by purulence of the joint fluid, purulence surrounding the prosthesis and/or acute inflammation seen on histopathology in periprosthetic tissue. Joint fluid and periprosthetic tissue cultures were performed by our routine Clinical Microbiology Laboratory. In addition, explanted joint components were sonicated for 5 min at 40 kHz and then aliquots of sonicate were plated onto 10 blood agar plates. Any antimicrobial therapy in the month before specimen collection (joint aspiration or arthroplasty surgery) was recorded.
Results: To date, 17 patients with PJI have been studied (15 knee and 2 hip prostheses). In 16 patients the causative microorganism was recovered: coagulase-negative staphylococci (11), Staphylococcus aureus (3), Corynebacterium spp. (1), and viridans group streptococcus (1). 10 patients had received an oral or intravenous antimicrobial agent in the month prior to specimen collection: levofloxacin (3), ceftriaxone (2), cephalexin (2), vancomycin (1), penicillin V (1), cotrimoxazole (1). In 9 patients the antimicrobial agent was discontinued 2 weeks prior surgery. 1 patient received levofloxacin until the time of surgery and S. aureus was isolated in all clinical specimens. Culture sensitivity relative to the above definition of PJI in patient with and without prior antimicrobial treatment is shown in Table:
| Prior Antimicrobial Treatment | No | Yes |
| Joint Fluid | 6/7 = 86% | 4/7 = 57% |
| Periprosthetic Tissue | 5/7 = 71% | 6/10 = 60% |
| Explant Sonicate | 7/7 = 100% | 7/10 = 70% |
Discussion: The explant sonicate showed the highest culture sensitivity. Regardless of the type of the clinical specimen, culture sensitivity was reduced in patients who had received prior antimicrobial therapy, despite discontinuation of this therapy 2 weeks prior specimen collection.
Significance: Explanted prosthesis sonicate as compared to synovial fluid or periprosthetic tissue improved culture sensitivity for diagnosis of PJI. Discontinuation of antimicrobial therapy > 2 weeks prior to surgery may further improve culture sensitivity.
