Diagnosis of periprosthetic joint bacterial infections by culture of sonication fluid from infected implants.

Purpose: This study compared the results of a culture method using sonication with those yielded by the conventional culture method, for patients with infected total knee arthroplasty (TKA). We also evaluated the usefulness of sonication for the identification of pathogens in infected TKA cases.

Methods: Isolates were cultured from 13 implants that had been removed from 13 patients with infected TKA. Preoperative culture was performed on aspirated joint fluid, and during the operation, infected tissue was collected for culture. The removed prosthetic implants were cultured before and after sonication. Next, we identified the cultured bacteria using API biochemical kits and 16 S rRNA sequencing.

Results: The cultures from preoperative joint fluid and intraoperative tissue were positive in 9 of 13 cases (69.2%). For the removed implants, 10 cases were positive before sonication. After sonication, 12 cases (92.3%) had positive cultures. The pathogen most commonly isolated from the cultures was Staphylococcus aureus.

Conclusions: This study found that a culturing workflow incorporating sonication diagnosed pathogens in patients with infected TKA with higher sensitivity than did the conventional culturing method.