Accuracy of the InnowaveDX MTB/RIF test for detection of Mycobacterium tuberculosis and rifampicin resistance: a prospective multicentre study

Mycobacterium tuberculosis: immune response, biomarkers, and therapeutic intervention

Although tuberculosis (TB) is an infectious disease, the progression of the disease following Mycobacterium tuberculosis (MTB) infection is closely associated with the host's immune response. In this review, a comprehensive analysis of TB prevention, diagnosis, and treatment was conducted from an immunological perspective. First, we delved into the host's immune response mechanisms against MTB infection as well as the immune evasion mechanisms of the bacteria. Addressing the challenges currently faced in TB diagnosis and treatment, we also emphasized the importance of protein, genetic, and immunological biomarkers, aiming to provide new insights for early and personalized diagnosis and treatment of TB. Building upon this foundation, we further discussed intervention strategies involving chemical and immunological treatments for the increasingly critical issue of drug-resistant TB and other forms of TB. Finally, we summarized TB prevention, diagnosis, and treatment challenges and put forward future perspectives. Overall, these findings provide valuable insights into the immunological aspects of TB and offer new directions toward achieving the WHO's goal of eradicating TB by 2035.

Association of lineage 4.2.2 of Mycobacterium tuberculosis with the 63-bp deletion variant of the mpt64 gene

IMPORTANCE

To date, rapid diagnostic methods based on the MPT64 antigen assay are increasingly utilized to differentiate between non-tuberculous mycobacteria and TB disease in clinical settings. Furthermore, numerous novel techniques based on the MPT64 release assay are continuously being developed and applied for the identification of both pulmonary and extrapulmonary TB. However, the diagnostic accuracy of the MPT64 antigen assay is influenced by the presence of 63 bp deletion variants within the mpt64 gene. To our knowledge, this is the first report on the association between the 63 bp deletion variant in mpt64 and Mycobacterium tuberculosis L4.2.2 globally, which highlights the need for the cautious utilization of MPT64-based testing in regions where L4.2.2 isolates are prevalent, such as China and Vietnam, and MPT64 negative results should be confirmed with another assay. In addition, further studies on vaccine development and immunology based on MPT64 should consider these isolates with 63 bp deletion variant.

Real-time recombinase-aided amplification assay for rapid amplification of the IS1081 gene of Mycobacterium tuberculosis

Mycobacterium tuberculosis (MTB), the etiological agent of tuberculosis (TB), is the leading cause of death due to a single infectious agent worldwide. Rapid and accurate diagnosis of MTB is critical for controlling TB especially in resource-limited countries, since any diagnosis delay increases the chances of transmission. Here, a real-time recombinase-aided amplification (RAA) assay targeting conserved positions in IS1081 gene of MTB, is successfully established to detect MTB. The intact workflow was completed within 30 min at 42 °C with no cross-reactivity observed for non-tuberculous mycobacteria and other clinical bacteria, and the detection limit for recombinant plasmid of MTB IS1081 was 163 copies/reaction at 95% probability, which was approximately 1.5-fold increase in analytical sensitivity for the detection of MTB, compared to conventional quantitative real-time PCR (qPCR; 244 copies/reaction). Furthermore, the result of clinical performance evaluation revealed an increased sensitivity of RAA assay relative to qPCR was majorly noted in the specimens with low bacteria loads. Our results demonstrate that the developed real-time RAA assay is a convenient, sensitive, and low-cost diagnostic tool for the rapid detection of MTB.

Evaluation of the performances of InnowaveDx MTB-RIF assay in the diagnosis of pulmonary tuberculosis using bronchoalveolar lavage fluid

OBJECTIVE

To evaluate the tuberculosis diagnostic performance of the InnowaveDx MTB-RIF assay (InnowaveDx test) in bronchoalveolar lavage fluid (BALF).

METHODS

A total of 213 BALF samples from suspected PTB patients were analyzed. AFB smear, culture, Xpert, Innowavedx test, CapitalBio test and simultaneous amplification and testing (SAT) were performed.

RESULTS

Of the 213 patients included in the study, 163 were diagnosed with PTB, and 50 were TB negative. Using the final clinical diagnosis as the reference, the sensitivity of InnowaveDx assay was 70.6%, which was significantly higher than the values achieved using the other methods (P < 0.05), and the specificity was 88.0%, which was comparable with other methods (P > 0.05). Among the 83 PTB cases with negative culture results, the detection rate of InnowaveDx assay was significantly higher than those of AFB smear, Xpert, CapitalBio test and SAT (P < 0.05). Kappa analysis was used to compare the agreement of InnowaveDx and Xpert in detecting RIF sensitivity, and the result showed the Kappa value was 0.78.

CONCLUSIONS

The InnowaveDx test is a sensitive, rapid and cost-effective tool for PTB diagnosis. In addition, the sensitivity of InnowaveDx to RIF in samples with low TB load should be interpreted with caution in light of other clinical data.