Infection of the joint or bone can be a serious medical condition that often leads to joint replacement. Even a routine replacement of the joint that is not related to infection can result in infection due to the surgery. In the United States in 2006, roughly 800,000 joint replacements
were performed and it is estimated that by 2030, there will be 4 million hip and knee replacements annually. For patients having a joint replaced, there is an increased risk of infection – roughly 1-2% of prosthetic hip or knee replacements result in an infection.
Diagnosis of bone and joint infections (BJI) can often be delayed and is reliant on cultures of the disease materials. Despite more push for molecular methods, there has been pushback. A new study though sought to assess the value of utilizing polymerase chain reaction (PCR) to help improve diagnostics and etiological evaluation of BJI. Over the course of 4 years, investigators at the Lariboisiere University Hospital in Paris, France, conducted a prospective study assessing a range of joint infections including spondylodiscitis, septic arthritis, prosthetic joint infections, and respective non-infected groups. Their results were published in a report in Open Forum Infectious Diseases
Patients were evaluated through clinical and radiological data at their initial visit and during follow-up appointments. Samples were analyzed through both traditional culture methods and then 16s rDNA PCR. Furthermore, an independent analysis via expert committee review was performed to confirm if there was a joint infection in the case or control group. Sensitivity was measured by combining the culture and PCR to that of the culture alone.
The expert panel reviewed and confirmed 105 cases of BJI and 111 control cases, which were then analyzed. Of those BJIs, there were several common pathogens causing infection. According to the report, 30% were staphylococci, 19% were Mycobacterium tuberculosis, and 14% were streptococci. Integrating the PCR into the diagnostic process enhanced the sensitivity when compared to the culture alone. For non-staphylococci BJI, the sensitivity was 81.6% with the PCR, versus 71.3% without, which was statistically significant.
The same could be found for the diagnosis of M tuberculosis spondylodiscitis, where the diagnostic specificity went from 42.2% to 64.4% when the PCR was brought in. Moreover, when the 16s PCR was used, it helped detect those BJIs related to uncommon bacteria, which helped facilitate more accurate treatment.
Ultimately, joint infections are tricky to truly diagnose and as these investigators have shown, integrating PCR into this process can improve diagnostic sensitivity. Definitions for joint or bone infections can be seen in the US Centers for Disease Control (CDC)’s National Healthcare Safety Network
These definitions shed light on the multiple facets that go into diagnosis of BJI. The culture is a critical component to identifying BJIs but is inherently limited, which makes the increased sensitivity of the PCR much more important for patient safety and overall diagnostics.
Furthermore, use of PCR has the potential to provide antimicrobial sensitivities more quickly, which can help guide treatment and reduce the chance for resistance. Overall, this study reveals an optimistic future for use of PCR in the diagnosis of BJIs and should encourage more investment into this as a tool to enhance medicine and public health.