Usefulness of a Multiplex PCR Assay for the Diagnosis of Prosthetic Joint Infections in the Routine Setting

OBJECTIVE: To evaluate the usefulness of a multiplex polymerase chain reaction (PCR) assay as a complementary tool in the diagnosis of prosthetic joint infections in the routine setting of a clinical microbiology laboratory, with a special focus on patients at high risk of culture‐negative infections and high suspicion of infection. METHODS: The results obtained in the routine care setting with the use of the commercial multiplex PCR (Unyvero i60©, Curetis AG, Holzgerlingen, Germany) were retrospectively reviewed. The test was performed in samples of patients with suspected prosthetic joint infection, which were also processed for conventional diagnostic methods, including sonication of the implant when possible. Patients selected for the test were those with negative cultures after a 24‐h incubation period. RESULTS: Ninety‐nine PCRs were performed, 57 of which were diagnostic of infection according to 2018 MSIS criteria. Nine patients received antibiotics within the 15 days prior to the diagnostic procedure. Tested samples included synovial fluid (33), sonication fluid (56) and tissue biopsies (10). The PCR test detected microorganisms in 26 samples: including two cases of polymicrobial infection. Eleven patients were diagnosed by using PCR only. The most frequently detected microorganism in PCR was Coagulase‐Negative Staphylococcus in 11 samples, followed by Staphylococcus aureus in five. One sample was positive for the bacteria universal primer, included in the 2.0 version of the kit. Only one discrepancy was detected between a negative PCR and a positive culture. One sample was also positive for a resistance marker (detection of mecA gene in a case of methicillin‐resistant S. aureus infection). CONCLUSION: The incorporation of the Unyvero ITI multiple PCR technique in patients selected by clinical experts is a useful tool for the diagnosis of bone and joint infections in a routine care setting. A close clinical‐microbiological collaboration improves the usefulness of this kit for the management of patients with these infections.