Polymerase Chain Reaction as an Adjunct to Conventional Culture for Periprosthetic Joint Infection Diagnosis

Periprosthetic joint infection (PJI) remains one of the most challenging complications after total joint arthroplasty. While conventional culture remains the standard for identification of causative pathogens in PJI, rapid identification techniques such as polymerase chain reaction (PCR) are becoming increasingly popular, with little comparative data.

A retrospective review was performed on a database of consecutive patients who underwent workup for PJI at a tertiary referral center from January 1, 2023, to May 31, 2025. Patients who underwent both standard synovial fluid culture and a PCR panel on the same day were included. Synovial fluid culture was used as the reference standard, and test result concordance and turnaround time were assessed.

Results from the PCR panel showed strong agreement with synovial fluid culture in the 225 cases analyzed, with 88% culture-positive agreement. The PCR false negatives were due to organisms not included in the PCR panel (n = 6), a false-positive culture from contamination (n = 1), and a patient who had a PJI due to Candida parapsilosis (n = 2). When only considering true positives with organisms included in the panel, the PCR displayed a 97.1% culture-positive agreement. The panel also detected organisms in eight culture-negative cases (94.7% culture-negative agreement). Those cases each met the 2018 International Consensus Meeting definition of PJI, were treated as PJIs, and their negative-culture results were hypothesized to be due to antibiotic use before culture. The panel's turnaround time (median 8.4 hours) is significantly faster than both culture-positive (P < 0.001) (69.2 hours) and culture-negative (P < 0.001) (139.5 hours) results from synovial fluid culture.

The high concordance between the panel and conventional culture techniques suggests that PCR may be added as an adjunctive diagnostic tool for PJI workup after total joint arthroplasty. Our results also suggest that PCR may be more accurate than fluid culture in patients who have current antibiotic usage. The PCR's advantage of rapid turnaround time is particularly helpful in the timely optimization of antibiotic therapy.

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