Diagnostic performance of non- and microbiologic tests
PJIs
The positivity rates of all non-microbiological and microbiological diagnostic tests are shown in Positivity rates of non- and microbiologic tests.The results are shown as numbers of cases (percentages). CRP, C-reactive protein; ESR, Erythrocyte sedimentation rate; PMN, Polymorphonuclear neutrophil. SF, Synovial fluid; DT, Deep tissue. mNGS, Metagenomic next-generation sequencing.Of the 131 cases, 66 (50.4%) had positive synovial fluid cultures, 59 (45.0%) had two or more positive deep tissue cultures, 81 (61.8%) had one or more positive deep tissue cultures, and 22 (16.8%) had a single positive deep tissue culture. In addition, of the 22 cases with single positive deep tissue cultures, 17 (77.3%) were found to have identical pathogens in synovial fluid culture and/or mNGS testing. In the remaining 5 cases, the pathogen detected in the single positive tissue culture did not correlate with the pathogen detected in the synovial fluid cultures or mNGS tests, suggesting the possibility of contamination. When combining positive synovial fluid cultures and positive deep tissue cultures, the overall positivity rate was 69.5% (91 of 131 cases), which was a significantly lower percentage compared to the positivity rate of mNGS (115 of 131 cases [87.8%], p < 0.001). When compared with all cultures from all sources (deep tissue and synovial fluid), mNGS was able to identify identical pathogens in 90.1% (82/91) of culture-positive PJIs, with additional potential pathogens detected in 15.4% (14/91). Potential pathogens were detected in 70.0% (28/40) of culture-negative PJIs.