Sonication of explanted prosthesis combined with incubation in BD bactec bottles for pathogen-based diagnosis of prosthetic joint infection.

Prosthetic joint infection (PJI) is a rare but refractory complication of arthroplasty. Accurate identification of pathogens is a key step for successful treatment of PJI, which remains a challenge for clinicians and laboratory workers. We designed a combined culture method with sonication of implants and incubation in a BD Bactec system to improve the effectiveness of pathogen diagnosis in PJI. The aims of this study were to investigate the diagnostic accuracy of sonicate fluid cultures in the BD Bactec system and to compare the results with those of synovial fluid cultures in the BD Bactec system. The prosthetic components removed were sonicated in Ringer's solution, and then sonicate fluid was incubated in Bactec bottles for 5 days. Synovial fluid was incubated in Bactec bottles for 5 days as a control. Synovial fluid cultures with Bactec bottles and sonicate fluid cultures with Bactec bottles showed sensitivities of 64% and 88%, respectively (P = 0.009), with specificities of 98% and 87% (P = 0.032), respectively. Sonicate fluid cultures with Bactec bottles were more sensitive than synovial fluid cultures with Bactec bottles regardless of whether antimicrobial agents were used within 14 days before surgery (81% versus 52%; P = 0.031) or not (93% versus 72%; P = 0.031). Sonication of explanted prostheses followed by incubation of the resulting sonicate fluid in Bactec bottles detected many more pathogens than did synovial fluid cultures with Bactec bottles. This method is also effective in cases with antibiotic treatment before surgery.