The Performance of the Abbott Real Time MTB RIF/INH Compared to the MTBDRplus V2 for the Identification of MDR-TB Among Isolates

Rapid Diagnosis of Drug-Resistant Tuberculosis-Opportunities and Challenges

Global tuberculosis (TB) eradication is undermined by increasing prevalence of emerging resistance to available drugs, fuelling ongoing demand for more complex diagnostic and treatment strategies. Early detection of TB drug resistance coupled with therapeutic decision making guided by rapid characterisation of pre-treatment and treatment emergent resistance remains the most effective strategy for averting Drug-Resistant TB (DR-TB) transmission, reducing DR-TB associated mortality, and improving patient outcomes. Solid- and liquid-based mycobacterial culture methods remain the gold standard for Mycobacterium tuberculosis (MTB) detection and drug susceptibility testing (DST). Unfortunately, delays to result return, and associated technical challenges from requirements for specialised resource and capacity, have limited DST use and availability in many high TB burden resource-limited countries. There is increasing availability of a variety of rapid nucleic acid-based diagnostic assays with adequate sensitivity and specificity to detect gene mutations associated with resistance to one or more drugs. While a few of these assays produce comprehensive calls for resistance to several first- and second-line drugs, there is still no endorsed genotypic drug susceptibility test assay for bedaquiline, pretomanid, and delamanid. The global implementation of regimens comprising these novel drugs in the absence of rapid phenotypic drug resistance profiling has generated a new set of diagnostic challenges and heralded a return to culture-based phenotypic DST. In this review, we describe the available tools for rapid diagnosis of drug-resistant tuberculosis and discuss the associated opportunities and challenges.

Pyrosequencing for diagnosis of multidrug and extensively drug-resistant tuberculosis: A systemic review and meta-analysis

Background

Multidrug and extensively drug-resistant tuberculosis (M/XDR-TB) pose major threats to global health. Diagnosis accuracy and delay have been the major drivers for the upsurge of M/XDR-TB. Pyrosequencing (PSQ) is a novel, real-time DNA sequencing for rapid detection of mutations associated with M/XDR-TB. We aimed to systematically synthesize the evidence on the diagnostic accuracy of PSQ for M/XDR-TB.

Methods

We conducted an electronic search of PubMed, Embase, Biosis, Web of Science, and Google Scholar up to March 2020. We used the QUADAS‐2 (Quality Assessment of Diagnostic Accuracy Studies) tool to assess the quality of studies, the BRMA (bivariate random‐effects meta-analysis) model to synthesize diagnostic accuracies, and the Rev-Man 5.4 software to perform the meta-analyses. We analyzed dichotomous data using the risk ratio (RR) with a 95% confidence interval. PROSPERO Registration ID: CRD42020200817.

Results

The analysis included seven studies, with a total sample of 3,165. At 95% confidence interval, the pooled sensitivity and specificity of PSQ were 89.7 (CI: 83.5–93.8) and 97.8 (CI: 94.9–99.1) for Isoniazid, 94.6 (CI: 90.9–96.8) and 98.5 (CI: 96.5–99.3) for Rifampicin, 87.9 (CI: 81.2–92.4) and 98.8 (CI: 97.2–99.5) for Fluoroquinolone, 83.5 (CI: 72.8–90.5) and 99.4 (CI: 98.3–99.8) for Amikacin, 79 (CI: 67–8-87) and 97.9 (CI: 95.5–99) for Capreomycin, and 69.6 (CI: 57–79.8) and 98.2 (CI: 95.9–99.2) for Kanamycin. The overall pooled sensitivity and specificity were 85.8 (CI: 76.7–91.7) and 98.5 (CI: 96.5–99.3), respectively.

Conclusion

According to the pooled data, PSQ is highly sensitive and specific for detecting M/XDR-TB, both from clinical specimens and culture isolates, and within a shorter turnaround time. We suggest a continued synthesis of the evidence on the cost-effectiveness and technical feasibilities of PSQ in low-income countries context, including sub-Saharan Africa.