Ergonomic Diagnostic Tool based on Chip Mini RT-PCR for Diagnosis of Pulmonary and Extra Pulmonary Tuberculosis

Evaluation of truenat assays for the diagnosis of pulmonary and extrapulmonary tuberculosis: a systematic review and meta-analysis

BACKGROUND

Tuberculosis (TB) remains a significant global health concern, necessitating accurate and timely diagnostic methods. This study aimed to conduct a systematic review and meta-analysis to assess the diagnostic accuracy of Truenat assays for both pulmonary TB (PTB) and extrapulmonary TB (EPTB).

METHOD

PubMed, Scopus, and Web of Science were systematically searched for studies comparing Truenat assays to Mycobacterium tuberculosis confirmation methods.

RESULTS

Comparing Truenat MTB assay with the Lowenstein-Jensen (LJ) culture, the pooled sensitivity and specificity were 86% (95% CI: 79-91%) and 86% (95% CI: 82-90%), respectively. For Mycobacterial Growth Indicator Tube (MGIT) culture comparison, pooled sensitivity was 88% (95% CI: 82-92%) with a specificity of 79% (95% CI: 57-92%). Compared to smear microscopy, Truenat assays displayed pooled sensitivity and specificity of 92% (95% CI: 78-98%) and 86% (95% CI: 64-95%). In comparison to Xpert MTB/RIF, Truenat assays exhibited a pooled sensitivity of 92% (95% CI: 80-97%) and a pooled specificity of 92% (95% CI: 56-99%) for PTB detection, and a pooled sensitivity of 94% (95% CI: 81-98%) and a specificity of 77% (95% CI: 32-96%) for the diagnosis of EPTB.

CONCLUSION

This study underscores the potential of Truenat assays as valuable tools for diagnosing both PTB and EPTB.

PROSPERO ID

CRD42024526686.

Diagnosis of extrapulmonary tuberculosis by GeneXpert MTB/RIF Ultra assay

INTRODUCTION

Diagnosis of extrapulmonary tuberculosis (EPTB) is an arduous task owing to different anatomical locations, unusual clinical presentations, and sparse bacillary load in clinical specimens. Although GeneXpert® MTB/RIF is a windfall in TB diagnostics including EPTB, it yields low sensitivities but high specificities in many EPTB specimens. To further improve the sensitivity of GeneXpert®, GeneXpert® Ultra, a fully nested real-time PCR targeting IS6110, IS1081 and rpoB (Rv0664) has been endorsed by the WHO (2017), wherein melt curve analysis is utilized to detect rifampicin-resistance (RIF-R).

AREA COVERED

We described the assay chemistry/work design of Xpert Ultra and evaluated its performance in several EPTB types, that is, TB lymphadenitis, TB pleuritis, TB meningitis, and so on, against the microbiological reference standard or composite reference standard. Notably, Xpert Ultra exhibited better sensitivities than Xpert, but mostly at the compensation of specificity values. Moreover, Xpert Ultra exhibited low false-negative and false-positive RIF-R results, compared with Xpert. We also detailed other molecular tests, that is, Truenat MTBTM/TruPlus, commercial real-time PCR, line probe assay, and so on, for EPTB diagnosis.

EXPERT OPINION

A combination of clinical features, imaging, histopathological findings, and Xpert Ultra are adequate for definite EPTB diagnosis so as to initiate an early anti-tubercular therapy.

Insight into diagnosis of pleural tuberculosis with special focus on nucleic acid amplification tests

INTRODUCTION

Pleural tuberculosis (TB) is the archetype of extrapulmonary TB (EPTB), which mainly affects the pleural space and leads to exudative pleural effusion. Diagnosis of pleural TB is a difficult task predominantly due to atypical clinical presentations and sparse bacillary load in clinical specimens.

AREA COVERED

We reviewed the current literature on the globally existing conventional/latest modalities for diagnosing pleural TB. Bacteriological examination (smear/culture), tuberculin skin testing/interferon-γ release assays, biochemical testing, imaging and histopathological/cytological examination are the main modalities. Moreover, nucleic acid amplification tests (NAATs), i.e. loop-mediated isothermal amplification, PCR/multiplex-PCR, nested-PCR, real-time PCR and GeneXpert® MTB/RIF are being utilized. Currently, GeneXpert Ultra, Truenat MTB^TM, detection of circulating Mycobacterium tuberculosis (Mtb) cell-free DNA by NAATs, aptamer-linked immobilized sorbent assay and immuno-PCR (I-PCR) have also been exploited.

EXPERT OPINION

Routine tests are not adequate for effective pleural TB diagnosis. The latest molecular/immunological tests as discussed above, and the other tools, i.e. real-time I-PCR/nanoparticle-based I-PCR and identification of Mtb biomarkers within urinary/serum extracellular vesicles being utilized for pulmonary TB and other EPTB types may also be exploited to diagnose pleural TB. Reliable diagnosis and early therapy would reduce the serious complications associated with pleural TB, i.e. TB empyema, pleural fibrosis, etc.

Fabrication of an Oscillating Thermocycler to Analyze the Canine Distemper Virus by Utilizing Reverse Transcription Polymerase Chain Reaction

The reverse transcription-polymerase chain reaction (RT-PCR) has been utilized as an effective tool to diagnose the infectious diseases of viruses. In the present work, the oscillating thermocycler is fabricated and performed to carry out the one-step RT-PCR process successfully. The ribonucleic acid (RNA) mixture is pipetted into the fixed sample volume inside an aluminum reaction block. The sample oscillates the pathway onto the linear motion control system and through the specific RT-PCR heating zones with individual homemade thermal control modules. The present oscillating thermocycler combines the merits of the chamber type and the CF type systems. Before PCR, the reaction chamber moves to the low-temperature zone to complete the RT stage and synthesize the complementary deoxyribonucleic acid (DNA). Next, the low-temperature zone is regulated to the annealing zone. Furthermore, the reactive sample is moved back and forth among three isothermal zones to complete PCR. No extra heating zone is required for the RT stage. The total length of the moving displacement of the chamber is within 100 mm. The miniaturization of the oscillating thermocycler can be expected. In our oscillatory device, the denaturation zone located between the annealing and extension zones is suggested as the appropriate arrangement of the heating blocks. Heat management without thermal cross-talk is easy. Finally, an improved oscillating device is demonstrated to execute the RT-PCR process directly, utilized to amplify the canine distemper virus templates successfully, which could be well applied to a low-cost DNA analysis system in the future.

A prospective multicentre diagnostic accuracy study for the Truenat tuberculosis assays

Background

Bringing reliable and accurate tuberculosis (TB) diagnosis closer to patients is a key priority for global TB control. Molbio Diagnostics have developed the Truenat point-of-care molecular assays for detection of TB and rifampicin (RIF) resistance.

Methods

We conducted a prospective multicentre diagnostic accuracy study at 19 primary healthcare centres and seven reference laboratories in Peru, India, Ethiopia and Papua New Guinea to estimate the diagnostic accuracy of the point-of-care Truenat MTB, MTB Plus and MTB-RIF Dx assays for pulmonary TB using culture and phenotypic drug susceptibility testing as the reference standard, compared with Xpert MTB/RIF or Ultra.

Results

Of 1807 enrolled participants with TB signs/symptoms, 24% were culture-positive for Mycobacterium tuberculosis, of which 15% were RIF-resistant. In microscopy centres, the pooled sensitivity of Truenat MTB and Truenat MTB Plus was 73% (95% CI 67–78%) and 80% (95% CI 75–84%), respectively. Among smear-negative specimens, sensitivities were 36% (95% CI 27–47%) and 47% (95% CI 37–58%), respectively. Sensitivity of Truenat MTB-RIF was 84% (95% CI 62–95%). Truenat assays showed high specificity. Head-to-head comparison in the central reference laboratories suggested that the Truenat assays have similar performance to Xpert MTB/RIF.

Conclusion

We found the performance of Molbio's Truenat MTB, MTB Plus and MTB-RIF Dx assays to be comparable to that of the Xpert MTB/RIF assay. Performing the Truenat tests in primary healthcare centres with very limited infrastructure was feasible. These data supported the development of a World Health Organization policy recommendation of the Molbio assays.

Diagnostic performance of point-of-care Truenat assays in primary healthcare centres is comparable to that of Xpert MTB/RIF placed in reference laboratories. The WHO now recommends Truenat as an initial test for detection of TB and RIF resistance.https://bit.ly/31Wj3S6

Point-of-care diagnostics for infectious diseases: From methods to devices

The current widespread of COVID-19 all over the world, which is caused by SARS-CoV-2 virus, has again emphasized the importance of development of point-of-care (POC) diagnostics for timely prevention and control of the pandemic. Compared with labor- and time-consuming traditional diagnostic methods, POC diagnostics exhibit several advantages such as faster diagnostic speed, better sensitivity and specificity, lower cost, higher efficiency and ability of on-site detection. To achieve POC diagnostics, developing POC detection methods and correlated POC devices is the key and should be given top priority. The fast development of microfluidics, micro electro-mechanical systems (MEMS) technology, nanotechnology and materials science, have benefited the production of a series of portable, miniaturized, low cost and highly integrated POC devices for POC diagnostics of various infectious diseases. In this review, various POC detection methods for the diagnosis of infectious diseases, including electrochemical biosensors, fluorescence biosensors, surface-enhanced Raman scattering (SERS)-based biosensors, colorimetric biosensors, chemiluminiscence biosensors, surface plasmon resonance (SPR)-based biosensors, and magnetic biosensors, were first summarized. Then, recent progresses in the development of POC devices including lab-on-a-chip (LOC) devices, lab-on-a-disc (LOAD) devices, microfluidic paper-based analytical devices (μPADs), lateral flow devices, miniaturized PCR devices, and isothermal nucleic acid amplification (INAA) devices, were systematically discussed. Finally, the challenges and future perspectives for the design and development of POC detection methods and correlated devices were presented. The ultimate goal of this review is to provide new insights and directions for the future development of POC diagnostics for the management of infectious diseases and contribute to the prevention and control of infectious pandemics like COVID-19.

Towards PCB-Based Miniaturized Thermocyclers for DNA Amplification

In recent years, printed circuit board (PCB)-based microfluidics have been explored as a means to achieve standardization, seamless integration, and large-scale manufacturing of microfluidics, thus paving the way for widespread commercialization of developed prototypes. In this work, static micro polymerase chain reaction (microPCR) devices comprising resistive microheaters integrated on PCBs are introduced as miniaturized thermocyclers for efficient DNA amplification. Their performance is compared to that of conventional thermocyclers, in terms of amplification efficiency, power consumption and duration. Exhibiting similar efficiency to conventional thermocyclers, PCB-based miniaturized thermocycling achieves faster DNA amplification, with significantly smaller power consumption. Simulations guide the design of such devices and propose means for further improvement of their performance.