By 
Infection of the joint or bone can be a serious medical condition that often leads to joint replacement. Even routine joint replacement that is unrelated to infection can lead to infection due to surgery. In the United States in 2006, approximately 800,000 joint replacements were performed and it is estimated that by 2030 there will be 4 million hip and knee replacements per year. For patients with a replaced joint, there is an increased risk of infection – about 1-2% of hip or knee replacements result in infection.
The diagnosis of bone and joint infections (IBJ) can often be delayed and depends on cultures of the pathological material. Despite more pressure for molecular methods, there has been a setback. A new study, however, has sought to assess the value of using the polymerase chain reaction (PCR) to help improve the diagnosis and etiologic assessment of IBC. For 4 years, researchers at CHU Lariboisière in Paris, France, conducted a prospective study evaluating a range of joint infections, including spondylodiscitis, septic arthritis, prosthetic joint infections and the respective uninfected groups. Their findings were published in a report in Open Forum on Infectious Diseases.
Patients were assessed using clinical and radiological data at their initial visit and at follow-up appointments. The samples were analyzed by the two traditional culture methods, then by 16s rDNA PCR. In addition, an independent analysis via an expert committee was performed to confirm whether there was a joint infection in the case or control group. Sensitivity was measured by combining culture and PCR with that of culture alone.
The expert group reviewed and confirmed 105 cases of BJI and 111 control cases, which were then analyzed. Among these IJBs, there were several common pathogens causing infection. According to the report, 30% were staphylococci, 19% were Mycobacterium tuberculosis and 14% were streptococci. Incorporating PCR into the diagnostic process improved sensitivity compared to culture alone. For non-staphylococcal IJBs, the sensitivity was 81.6% with PCR, compared to 71.3% without, which was statistically significant.
The same was true for the diagnosis of M tuberculosis spondylodiscitis, where the diagnostic specificity increased from 42.2% to 64.4% when PCR was performed. which made it possible to facilitate a more precise treatment.
Ultimately, joint infections are difficult to truly diagnose, and as these researchers have shown, incorporating PCR into this process can improve diagnostic sensitivity. Definitions of joint or bone infections can be found in the National Healthcare Safety Network (NHSN) of the US Centers for Disease Control (CDC).
These definitions highlight the many facets that go into diagnosing IBC. Culture is an essential part of identifying IJBs, but is inherently limited, making the increased sensitivity of PCR much more important for patient safety and overall diagnosis.
Additionally, the use of PCR has the potential to deliver antimicrobial sensitivities more quickly, which can help guide treatment and reduce the risk of resistance. Overall, this study reveals an optimistic future for the use of PCR in the diagnosis of BMI and should encourage further investment in this area as a tool to improve medicine and public health.