Molecular techniques for diagnosing prosthetic joint infections

Prosthetic joint infections (PJI) can be broadly classed into two groups: those where there is a strong clinical suspicion of infection and those with clinical uncertainty, including 'aseptic loosening'. Confirmation of infection and identification of the causative organism along with provision of antibiotic susceptibility data are important stages in the management of PJI. Conventional microbiological culture and susceptibility testing is usually sufficient to provide this. However, it may fail due to prior antimicrobial treatment or the presence of unusual and fastidious organisms. Molecular techniques, in particular specific real-time and broad-range PCR, are available for diagnostic use in suspected PJI. In this review, we describe the techniques available, their current strengths, limitations and future development. Real-time pathogen-specific and broad-range PCR (with single sequence determination) are suitable for use as part of the routine diagnostic algorithm for clinically suspected PJI. Further development of broad-range PCR with high-throughput (next-generation) sequencing is necessary to understand the microbiome of the prosthetic joint further before this technique can be used for routine diagnostics in clinically unsuspected PJI, including aseptic loosening.