Fragestellung Differential diagnostics of periprosthetic joint infection (PJI) remains a major
clinical challenge in orthopedic surgery. Correct and fast pathogen detection is a
key factor for the targeted antibiotic therapy and successful treatment. Alongside
the standard procedures, including blood samples and joint aspiration for cytometrie
and microbiology, and the use of serum and aspirate biomarkers, nucleic acid amplification
techniques (NAT) have shown promising results to enhance the diagnostics. The Unyvero
ITI system offers a multiplex PCR analysis for pathogens commonly associated with
PJI, however the analysis is quite costly, and the additional costs are not covered
by the german DRG hospital reimbursement system. Sensitivity and specificity can match
those of other techniques, but it generates a result within a few hours. If this can
actually lead to a faster and more accurate antibiotic therapy or other consequences
in therapeutic treatment is not know, nor is there any guideline on which patients
might profit from the additional analysis in PCR.
Methodik We performed a retrospective analysis of over 300 cases of revision arthroplasty
where PCR was employed to find out which patients actually benefitted from the analysis,
to assess the medical advantage for those patients as well as the possible economic
benefit for the treating instituion. We focused on those cases whre only PCR detected
a pathogen and on cases where positive PCR gave faster results than conventional microbiology,
as well as changes in antibiotic treatment due to the results of the PCR, and possibly
faster targeted treatment.
Ergebnisse und Schlussfolgerung Medium sensitivity (67 %) and high specificity (95 %) of the multiplex PCR in our
analysis matched the rates already published in the literature. On average, the results
of PCR were available 2.7 days earlier than those of conventional culture, but adaptation
of the antibiotic treatment due to the PCR result from an empiric to a calculated
therapy was rare, therefore most of the positive PCR results and no direct therapeutic
consequence. 21 out of 131 positive cases were positive only in the PCR, with Cutibacterium acnes being the most frequently detected pathogen in these cases and some with previous
antibiotic treatment; In these cases, the PCR analysis added significantly to targeted
treatment. Still, the “Number needed to diagnose” remains high.
We found no significant difference in economic parameters, such as length of stay
or number of revision surgeries in patients with positive PCR results, as opposed
to those where the PCR did not detect the pathogen.
Nucleic acid testing systems certainly can add to the diagnostic portfolio in revision
arthroplasty, with no other risk but an economic one associated with their use. Their
true impact on therapeutic decisions in daily routine is limited, and use should be
restricted to critical cases only.
Stichwörter periprosthetic joint infection; PCR; molecular biology; NAT
