Metagenomic next-generation sequencing of osteoarticular tissue for the diagnosis of suspected osteoarticular tuberculosis.

The objective of the study is to determine the accuracy of metagenomic next-generation sequencing (mNGS) in diagnosing osteoarticular tuberculosis (TB) infection and to compare it with mycobacteria growth indicator tube (MGIT) and Xpert assays. We retrospectively analyzed 162 patients admitted with suspected osteoarticular TB. Osteoarticular tissue (66.67%) and abscess specimens (33.33%) from patients were tested for MGIT, GeneXpert/RIF, and mNGS. mNGS assay detected 76 cases (46.9%) with bacterial, 63 cases (38.9%) with mycobacterial, 22 cases (13.6%) with fungal, and 1 case (0.6%) with actinomycetal organisms. These 162 pathogens were classified into 21 species. The most frequent species detected was Mycobacterium tuberculosis complex (29.0%), followed by Staphylococcus aureus (20.4%), Mycobacterium abscessus (5.6%), and Candida albicans (5.6%). Taking the "gold standard" TB diagnosis as the standard, the positive predictive values of mNGS, Xpert, and MGIT culture were both 100.00%. The negative predictive values of mNGS, Xpert, and MGIT culture and assays were 94.26%, 98.29%, and 88.46%, respectively. The sensitivity of mNGS detection (85.11%) was similar to that of Xpert (95.74%) and higher than that of MGIT culture (68.08%). The specificities of mNGS detection, Xpert, and MGIT culture were both 100.00%. The area under the curve value of the mNGS assay was 0.895 (95% CI: 0.830, 0.960), which was greater than that of the MGIT culture-based assay of 0.840 (95% CI: 0.757, 0.924), which was similar to 0.979 (95% CI: 0.945, 1.000) for Xpert assay. The pathogen detection rate of mNGS in diagnosing suspected osteoarticular TB exceeded that of conventional methods.

Importance: In the detection of unknown infectious disease pathogens, the overall efficacy of traditional detection methods, such as culture, is low, and traditional PCR testing is also limited to the gene sequences of known pathogenic microorganisms. Metagenomic next-generation sequencing (mNGS) performs DNA sequencing by studying the entire microbial community genome in a given sample, without the need for isolation and culture. Previous studies have shown that mNGS performs better on pulmonary and extrapulmonary samples when compared with Xpert, traditional pathogenetic tests, and even parallel diagnostics. However, it should be emphasized that only a few studies have explored the performance of mNGS in detecting Mycobacterium tuberculosis in clinical samples associated with bone and joint infections. We conducted this retrospective study to provide additional data to support the use of mNGS in the clinical setting to identify pathogens within abscesses or tissue samples associated with bone and joint infections.