Abstract
Aim
Bone and joint infections (BJIs) are serious infections requiring early optimized antimicrobial therapy. BJIs can be polymicrobial or caused by fastidious bacteria, and the patient may have received antibiotics prior to sampling, which may decrease the sensitivity of culture-based diagnosis. Furthermore, culture-based diagnosis can take up to 14 days. Molecular approaches can be useful to overcome these concerns. The BioFire® system performs syndromic multiplex PCR in 1 hour, with only a few minutes of sample preparation. The BioFire® Joint Infection (JI) panel (BF-JI), recently FDA-cleared, detects both Gram-positive (n=15) and Gram-negative bacteria (n=14), Candida, and eight antibiotic resistance genes directly from synovial fluids. The aim of this study was to evaluate its performance in acute JIs in real-life conditions.
Method
BF-JI was performed on synovial fluid from patients with clinical suspicion of acute JI, either septic arthritis or periprosthetic JI, in 6 French centers. The results of BF-JI were compared with the results of culture of synovial fluid and other concomitantly collected osteoarticular samples obtained in routine testing in the clinical microbiology laboratory.
Results
From July 2021 to May 2022, 319 patients (including 10 children < 5y and 136 periprosthetic infections) had been included in the study. The BF-JI test was invalid for one patient (not retested). Among the 318 remaining patients, overall concordance with comparative microbiology methods was 88% (280/318): 131 samples were negative with both BF-JI and culture, and 149 samples were positive with the same microorganisms using complementary techniques. In 33 cases (10.4%), BF-JI was negative while culture was positive: 18 microorganisms were not targeted by BF-JI (including Staphylococcus epidermidis, n=10, and Cutibacterium acnes, n=2); 15 microorganisms targeted by BF-JI were obtained in culture but not by the molecular test (false-negative 4.7%). In 20 cases, BF-JI was positive while culture was not: 12 patients had received antibiotics before sampling, and 7 cases involved fragile and fastidious bacteria (Kingella kingae, n=5; Neisseria gonorrhoeae, n=2). In 6 cases, both BF-JI and culture were positive, but no yielding the same bacteria (polymicrobial specimens).
Conclusions
In acute JIs, the BF-JI panel shows a good concordance with culture for the microorganisms targeted by the panel. Therefore, this molecular tool may have a place in microbiological diagnosis of acute JIs in order to confirm JI faster than culture. Moreover, it allows easy detection of difficult-to-culture bacteria.
Acknowledgements
study was supported by bioMérieux, who provided all reagents.
