Abstract
Aim
Periprosthetic joint infections (PJI) are a rare, but devastating complication. Diagnostic approaches to PJI vary greatly between different centers. Most commonly tissue biopsies and synovial fluid sampling are recommended for identification pathogens causing PJI. However, sensitivity and specificity of those techniques have been shown to be highly dependent on preanalytical factors like time and conditions of transportation, location of sampling, as well as analytical approaches and prolonged incubation for up to 14days. Sonication of explanted orthopedic devices has been shown to be more than only an addition in the diagnosis of PJI. The goal of this study was to evaluate the diagnostic value of sonication in PJI.
Method
Retrospective cohort analysis of orthopedic samples sent for sonication from 29 surgical centers between 06/2014–04/2017. Until 07/2015 samples were plated on Columbia-, MacConkey-, Chocolate- and Schaedler agar*, incubated aerobically and anaerobically for up to 14 days.
In 07/2015 an additional enrichment of 10ml per aerobic and anaerobic blood culture bottles* was introduced. The bottles were also incubated up to 14days and plated immediately if growth was detected.
Results
We evaluated 698 orthopedic samples sent for sonication, of which resulted in growth of one (n=355) or several (n=15) relevant pathogens. Coagulase negative staphylococci were isolated in 162 cases; Staphylococcus aureus was isolated in 67 cases, Propionibacterium spp. In 23 cases, Streptococcus spp. in 14 cases, Gram negative in 44 cases, Enterococcus spp. also in 14 cases and Candida spp. in 3 cases. The necessary time of incubation to growth was further decreased to 1.8 days (range: 0–13) days after introduction of additional incubation of sonicate fluid in blood-culture bottles. 92.7% of all positive samples showed growth before the 8th day of incubation.
Conclusions
Sonication of explanted orthopedic devices and culturing of the sonicate fluid provides a fast reliable tool for diagnosing pathogens of PJI/ODAI potentially without the need for prolonged incubation for up to 14 days. The additional incubation of the sonicate fluid in automated blood-culturing systems further improves the limit of detection and the time to growth.
*BioMerieux, Marcy étoile
