Rapid molecular detection of tuberculosis and rifampin resistance

Accuracy of GenoQuick MTB test in detection of Mycobacterium tuberculosis in sputum from TB presumptive patients in Uganda

Objective:

The objective of the study was to determine the diagnostic performance of the GenoQuick MTB test on heated sputum against the conventional Lowenstein–Jensen Mycobacterium tuberculosis culture as the reference method for tuberculosis diagnosis.

Introduction:

Fast, reliable, and easy-to-use tests for tuberculosis diagnosis are essential to achieving the Sustainable Development Goal of diagnosing and treating 90% of tuberculosis patients by 2030. We evaluated the diagnostic performance of the GenoQuick MTB, a polymerase chain reaction–lateral flow test, in Uganda, a resource-constrained, high tuberculosis- and HIV-burden setting.

Methods:

Fresh sputum samples from presumptive tuberculosis patients at Mulago Hospital were tested for M. tuberculosis using smear microscopy, GenoQuick MTB test, and Lowenstein–Jensen culture. For the GenoQuick MTB test, mycobacterial DNA was extracted by heating sputum at 95°C for 30 min while DNA amplification and detection were done following the manufacturer’s protocol (Hain Lifescience, Nehren, Germany). Sensitivity, specificity, and kappa agreements were calculated against Lowenstein–Jensen M. tuberculosis culture as a reference test using STATA V12.

Results:

Of the 86 tested samples, 30.2% had culture-confirmed pulmonary tuberculosis. Overall, sensitivity was higher for GenoQuick MTB (81%, 95% confidence interval: 60%−93%) than for smear microscopy (69%, 95% confidence interval: 48%−86%). Among people living with HIV, sensitivity was identical for GenoQuick MTB and smear tests (75%, 95% confidence interval: 42%−95%). Contrastingly, smear had a higher overall specificity (98%, 95% confidence interval: 91%−100%) than for GenoQuick MTB (92%, 95% confidence interval: 81%−97%). A similar trend of specificity was observed among the people living with HIV for smear microscopy (100%, 95% CI: 87%−100%) and for GenoQuick MTB (96%, 95% confidence interval: 81%−100%).

Conclusion:

The GenoQuick MTB test could be a potential tuberculosis diagnostic test given its higher sensitivity. Evaluation of this test in larger studies is recommended.

A university-clustered tuberculosis outbreak during the COVID-19 pandemic in eastern China

During the COVID-19 pandemic in 2020, a tuberculosis outbreak occurred in a university in eastern China, with 4,488 students and 421 staff on the campus. A 19-year-old student was diagnosed in August 2019. Later, the first round of screening was initiated among close contacts, but no active cases were found. Till September 2020, four rounds of screening were performed. Four rounds of screening were conducted on September 9, November 8, November 22-25 in 2019 and September 2020, with 0, 5, 0 and 43 cases identified, respectively. A total of 66 active tuberculosis were found in the same university, including 4 sputum culture-positive and 7 sputum smear-positive. The total attack rate of active tuberculosis was 1.34% (66/4909). The whole-genome sequencing showed that the isolates belonged to the same L2 sub-specie and were sensitive to all tested antituberculosis drugs. Delay detection, diagnosis and report of cases were the major cause of this university tuberculosis epidemic. More attention should be paid to the asymptomatic students in the index class. After the occurrence of tuberculosis cases in schools, multiple rounds of screening should be carried out, and preventive therapy should be applied in a timely manner.

Cost-effectiveness of GeneXpert Omni compared with GeneXpert MTB/Rif for point-of-care diagnosis of tuberculosis in a low-resource, high-burden setting in Eastern Uganda: a cost-effectiveness analysis based on decision analytical modelling

OBJECTIVE

To determine the cost-effectiveness of Xpert Omni compared with Xpert MTB/Rif for point-of-care diagnosis of tuberculosis among presumptive cases in a low-resource, high burden facility.

DESIGN

Cost-effectiveness analysis from the provider's perspective.

SETTING

A low-resource, high tuberculosis burden district in Eastern Uganda.

PARTICIPANTS

A provider's perspective was used, and thus, data were collected from experts in the field of tuberculosis diagnosis purposively selected at the local, subnational and national levels.

METHODS

A decision analysis model was contracted from TreeAge comparing Xpert MTB/Rif and Xpert Omni. Cost estimation was done using the ingredients' approach. One-way deterministic sensitivity analyses were performed to identify the most influential model parameters.

OUTCOME MEASURE

The outcome measure was incremental cost per additional test diagnosed expressed as the incremental cost-effectiveness ratio.

RESULTS

The total cost per test for Xpert MTB/Rif was US$14.933. Cartridge and reagent kits contributed to 67% of Xpert MTB/Rif costs. Sample transport costs increased the cost per test of Xpert MTB/Rif by $1.28. The total cost per test for Xpert Omni was $16.153. Cartridge and reagent kits contributed to over 71.2% of Xpert Omni's cost per test. The incremental cost-effectiveness ratio for using Xpert Omni as a replacement for Xpert MTB/Rif was US$30.73 per additional case detected. There was no dominance noted in the cost-effectiveness analysis, meaning no strategy was dominant over the other.

CONCLUSION

The use of Xpert Omni at the point-of-care health facility was more effective but with an increased cost compared with Xpert MTB/Rif at the centralised referral testing facility.

Evaluation of GeneXpert and liquid culture for detection of Mycobacterium tuberculosis in pediatric patients

PURPOSE

Evaluation of GeneXpert in comparison to liquid culture using Mycobacteria Growth Indicator Tube (MGIT) as gold standard for detection of Mycobacterium tuberculosis (MTB) in children.

METHODS

A total of 8123 samples, both pulmonary (5830) and extra pulmonary (2293) received from pediatric patients were processed for Acid Fast Bacilli (AFB) smear, GeneXpert and MGIT culture simultaneously.

RESULTS

Out of 8123 samples, 493 (6.1%) samples were found positive by GeneXpert and 508 (6.2%) samples by MGIT culture, 371 (4.6%) were found positive by both GeneXpert and MGIT culture. MGIT detected 137 (1.7%) extra positive than GeneXpert while GeneXpert detected 122 (1.5%) extra samples more positive than by MGIT. Sensitivity of GeneXpert was 73% and concordance between both methods was 96.8%. Rifampicin resistance was found in 49 (9.9%) samples among MTB positive by GeneXpert. Turnaround time for GeneXpert was approx. 2 ​h and for MGIT, it was 12-28 days.

CONCLUSION

Good sensitivity (73%) and concordance (96.8%) were observed for GeneXpert against MGIT culture in this study. GeneXpert can simultaneously detect MTB and rifampicin resistance in less than 2 ​h while MGIT takes 12-28 days for MTB detection only.

Genome-wide association studies of global Mycobacterium tuberculosis resistance to 13 antimicrobials in 10,228 genomes identify new resistance mechanisms

The emergence of drug-resistant tuberculosis is a major global public health concern that threatens the ability to control the disease. Whole-genome sequencing as a tool to rapidly diagnose resistant infections can transform patient treatment and clinical practice. While resistance mechanisms are well understood for some drugs, there are likely many mechanisms yet to be uncovered, particularly for new and repurposed drugs. We sequenced 10,228 Mycobacterium tuberculosis (MTB) isolates worldwide and determined the minimum inhibitory concentration (MIC) on a grid of 2-fold concentration dilutions for 13 antimicrobials using quantitative microtiter plate assays. We performed oligopeptide- and oligonucleotide-based genome-wide association studies using linear mixed models to discover resistance-conferring mechanisms not currently catalogued. Use of MIC over binary resistance phenotypes increased sample heritability for the new and repurposed drugs by 26% to 37%, increasing our ability to detect novel associations. For all drugs, we discovered uncatalogued variants associated with MIC, including in the Rv1218c promoter binding site of the transcriptional repressor Rv1219c (isoniazid), upstream of the vapBC20 operon that cleaves 23S rRNA (linezolid) and in the region encoding an α-helix lining the active site of Cyp142 (clofazimine, all p < 10-7.7). We observed that artefactual signals of cross-resistance could be unravelled based on the relative effect size on MIC. Our study demonstrates the ability of very large-scale studies to substantially improve our knowledge of genetic variants associated with antimicrobial resistance in M. tuberculosis.

A Global Bibliometric Analysis on Antibiotic-Resistant Active Pulmonary Tuberculosis over the Last 25 Years (1996–2020)

Background: Tuberculosis (TB) is still a leading global cause of mortality and an increasingly crucial problem in fighting TB is antibiotic resistance. We aimed to conduct a bibliometric analysis on the articles of the past 25 years on antibiotic-resistant active pulmonary TB. Methods: Appropriate keywords were combined using the Boolean and wildcard operators and searched in Scopus database for articles published between 1996 and 2020 in English language. For all the bibliometric analyses, the Bibliometrix package in RStudio and Biblioshiny web apps were used. We identified the publication and citation trends, topmost cited documents, most productive authors, countries and institutions and most influential journals and funding agencies. We constructed collaborative networks of countries and co-citations. In addition, we developed a Three-Fields plot and a Thematic Map to explore different publication themes. Results: We included 7024 articles (88.9% research articles) and a persistently increasing publication and citation trends were evident throughout the past 25 years. Boehme 2010 was the most cited paper (1609 times cited), Stefan Niemann was the most productive author (86 papers), and ‘International Journal of Tuberculosis and Lung Disease’ was the leading journal. Centers for Disease Control and Prevention was the top contributing institution (3.7% papers) and both US- and UK-based funders were leading. The most productive countries were the USA, India, the UK, South Africa, and China and most of the collaborations took place between the USA, the UK, and South Africa. Conclusion: Undoubtedly, researchers and funders from the USA dominated followed by the UK in most of the fields in antibiotic-resistant TB research. The outcomes of antibiotic-resistant TB research would be more productive and translational if researchers from low- or middle-income countries (especially from Africa, South America and Asia) with high research productivity and TB burden could be in collaboration with high-income countries exhibiting low TB burden.

Treatment with a three-drug regimen for pulmonary tuberculosis based on rapid molecular detection of isoniazid resistance: a non-inferiority randomized trial (FAST-TB)

Background

The rationale behind the use of ethambutol in the standard tuberculosis treatment is to prevent the emergence of resistance to rifampicin in case of primary resistance to isoniazid. We evaluated whether early detection of isoniazid resistance using molecular testing allows the use an ethambutol-free regimen.

Methods

FAST-TB, a phase 4, French, multicenter, open-label, non-inferiority trial, compared 2 strategies: (1) polymerase chain reaction (PCR)-based detection of isoniazid and rifampicin resistance at baseline using Genotype MTBDRplus version 2.0 followed by ethambutol discontinuation if no resistance was detected (PCR arm) and (2) a standard 4-drug combination, pending phenotypic drug-susceptibility results (C arm). Adult patients with smear-positive pulmonary tuberculosis were enrolled. The primary endpoint was the proportion of patients with treatment success defined as bacteriological or clinical cure at the end of treatment. A non-inferiority margin of 10% was used.

Results

Two hundred three patients were randomized, 104 in the PCR arm and 99 in the C arm: 26.6% were female, median age was 37 (interquartile range, 28–51) years, 72.4% were born in Africa, and 5.4% were infected with human immunodeficiency virus. Chest x-ray showed cavities in 64.5% of the cases. Overall, 169 patients met criteria of treatment success: 87 of 104 (83.7%) in the PCR arm and 82 of 99 (82.8%) in the C arm with a difference of +0.8% (90% confidence interval, −7.9 to 9.6), meeting the noninferiority criteria in the intention-to-treat population (P = .02).

Conclusions

In a setting with low prevalence of primary isoniazid resistance, a 3-drug combination with isoniazid, rifampicin, and pyrazinamide, based on rapid detection of isoniazid resistance using molecular testing, was noninferior to starting the recommended 4-drug regimen.

Accuracy of Tongue Swab Testing Using Xpert MTB-RIF Ultra for Tuberculosis Diagnosis

Tongue dorsum swabs have shown promise as alternatives to sputum for detecting Mycobacterium tuberculosis (MTB) in patients with pulmonary tuberculosis (TB). Some of the most encouraging results have come from studies that used manual quantitative PCR (qPCR) to analyze swabs. Studies using the automated Cepheid Xpert MTB/RIF Ultra qPCR test (Xpert Ultra) have exhibited less sensitivity with tongue swabs, possibly because Xpert Ultra is optimized for testing sputum, not tongue swab samples. Using two new sample preprocessing methods that demonstrated good sensitivity in preliminary experiments, we assessed diagnostic accuracy and semi-quantitative signals of Xpert Ultra performed on tongue swabs collected from 183 adults with presumed TB in Kampala, Uganda. Relative to a sputum Xpert Ultra reference standard, the sensitivity of tongue swab Xpert Ultra was 77.8% (95% confidence interval [CI] 64.4-88.0) and specificity was 100.0% (95% CI, 97.2-100.0). When compared to a microbiological reference standard (MRS) incorporating both sputum Xpert Ultra and sputum mycobacterial culture, sensitivity was 72.4% (95% CI, 59.1-83.3) and specificity remained the same. Semi-quantitative Xpert Ultra results were generally lower with tongue swabs than with sputum, and cycle threshold values were higher. None of the eight sputum Xpert Ultra "trace" or "very low" results were detected using tongue swabs. Tongue swabs should be considered when sputum cannot be collected for Xpert Ultra testing, or in certain mass-screening settings. Further optimization of tongue swab analysis is needed to achieve parity with sputum-based molecular testing for TB.

Stabilization of Tuberculosis Reporter Enzyme Fluorescence (REFtb) Diagnostic Reagents for Use at the Point of Care

Tuberculosis is one of the most frequent causes of death in humans worldwide. One of the primary reasons tuberculosis remains a public health threat is that diagnosis can take weeks to months, is often not very sensitive and cannot be accomplished in many remote environments. A rapid, sensitive and inexpensive point-of-care (POC) diagnostic would have a major impact on tuberculosis eradication efforts. The tuberculosis diagnostic system REFtb is based on specific detection of the constitutively expressed β-lactamase (BlaC) in Mycobacterium tuberculosis using a custom fluorogenic substrate designated as CDG-3. REFtb has potential as a diagnostic for tuberculosis that could be very inexpensive (<USD 2.00/test), used at the POC and could provide definitive diagnosis within 10 min. However, the reagents for REFtb are currently in liquid form, making them more susceptible to degradation and difficult to transport. We evaluated the improvement in the stability of REFtb reagents by lyophilization under a variety of conditions through their effects on the performance of REFtb. We found that lyophilization of REFtb components produces an easily reconstituted powder that displays similar performance to the liquid system and that lactose represents one of the most promising excipients for use in a final POC REFtb diagnostic system. These studies provide the foundation for the production of a stable POC REFtb system that could be easily distributed worldwide with minimal or no requirement for refrigeration.

Nucleic acid amplification tests reduce delayed diagnosis and misdiagnosis of pulmonary tuberculosis

The clinical impact of nucleic acid amplification (NAA) tests on reducing delayed diagnosis and misdiagnosis of pulmonary TB (PTB) has rarely been investigated. PTB patients were classified into a frontline NAA group, an add-on NAA group, and a no NAA group. The outcomes of interest were the proportion of PTB case died before anti-TB treatment, the interval between sputum examination and initiation of treatment, and misdiagnosis of PTB. A total of 2192 PTB patients were enrolled, including 282 with frontline NAA, 717 with add-on NAA, and 1193 with no NAA tests. Patients with NAA tests had a lower death rate before treatment initiation compared to those without NAA tests (1.6% vs. 4.4%, p < 0.001) in all cases. Patients with frontline NAA compared to those with add-on NAA and those without NAA, had a shorter interval between sputum examination and treatment initiation in all cases (3 days vs. 6 days (p < 0.001), vs 18 days (p < 0.001)), and less misdiagnosis in smear-positive cases (1.8% vs. 5.6% (p = 0.039), vs 6.5% (p = 0.026)). In conclusion, NAA tests help prevent death before treatment initiation. Frontline NAA tests perform better than add-on NAA and no NAA in avoiding treatment delay in all cases, and misdiagnosis of PTB in smear-positive cases.

Progression of LAMP as a Result of the COVID-19 Pandemic: Is PCR Finally Rivaled?

Reflecting on the past three years and the coronavirus disease 19 (COVID-19) pandemic, varying global tactics offer insights into the most effective public-health responses. In the US, specifically, rapid and widespread testing was quickly prioritized to lower restrictions sooner. Essentially, only two types of COVID-19 diagnostic tests were publicly employed during the peak pandemic: the rapid antigen test and reverse transcription polymerase chain reaction (RT-PCR). However, neither test ideally suited the situation, as rapid antigen tests are far too inaccurate, and RT-PCR tests require skilled personnel and sophisticated equipment, leading to long wait times. Loop-mediated isothermal amplification (LAMP) is another exceptionally accurate nucleic acid amplification test (NAAT) that offers far quicker time to results. However, RT-LAMP COVID-19 tests have not been embraced as extensively as rapid antigen tests or RT-PCR. This review will investigate the performance of current RT-LAMP-based COVID-19 tests and summarize the reasons behind the hesitancy to embrace RT-LAMP instead of RT-PCR. We will also look at other LAMP platforms to explore possible improvements in the accuracy and portability of LAMP, which could be applied to COVID-19 diagnostics and future public-health outbreaks.

Gene-Based Diagnosis of Tuberculosis from Oral Swabs with a New Generation Pathogen Enrichment Technique

A rapid and sensitive diagnosis is crucial for the management of tuberculosis (TB). A simple and label-free approach via homobifunctional imidoesters with a microfluidic platform (SLIM) assay showed a higher sensitivity than the Xpert MTB/RIF assay in the diagnosis of pulmonary TB (PTB). Here, we evaluated the efficacy of the SLIM assay for oral swab samples from cases of suspected PTB. Patients with clinically suspected PTB were prospectively enrolled and oral swab samples were processed using the SLIM assay and the attending physicians were blinded to the results of the SLIM assay. TB cases were defined as those treated with anti-TB chemotherapy for at least 6 months at the discretion of the specialists based on their clinical features and conventional laboratory results, including the Xpert assay. A total of 272 patients (with TB, n = 128 [47.1%]; without TB, n = 144 [52.9%]; mean age, 59.8 years) were enrolled. Overall, the sensitivity of the oral swab-based SLIM assay (65.6%) was higher than that of the sputum-based Xpert assay (43.4%; P = 0.001). Specifically, the SLIM oral swab assay showed a notably higher sensitivity in culture-negative TB cases compared with the Xpert assay (69.0% [95% CI: 49.2 to 84.7%] versus 7.4% [95% CI: 0.9 to 24.3%]; P = 0.001). The specificity of the SLIM and the Xpert assays was 86.1% (95% CI: 79.3 to 91.3%) and 100% (95% CI: 97.2 to 100%), respectively. When only culture-confirmed cases were analyzed, the SLIM oral swab was comparable to sputum Xpert in sensitivity (64.7% versus 54.3%, P = 0.26). The oral swab-based SLIM assay showed a superior sensitivity for TB diagnosis over the sputum-based Xpert assay, especially for culture-negative cases. IMPORTANCE The development of a rapid, accessible, and highly sensitive diagnostic tool is a major challenge in the control and management of tuberculosis. Gene-based diagnostics is recommended for the rapid diagnosis of pulmonary tuberculosis (PTB), but its sensitivity, such as Xpert MTB/RIF assay (Xpert), drops in cases with a low bacterial load. It can only be applied to sputum samples, and it is quite difficult for some patients to produce an adequate amount of sputum. We evaluated the clinical validity of an oral swab-based microfluidic system, i.e., the SLIM assay. The SLIM assay showed a significantly higher sensitivity than the Xpert assay, especially in smear-negative TB cases. This non-sputum-based SLIM assay can be a useful diagnostic test by overcoming the limitations of conventional sputum-based tests in pulmonary TB.

Nucleic Acids Detection for Mycobacterium tuberculosis Based on Gold Nanoparticles Counting and Rolling-Circle Amplification

Tuberculosis (TB) is a common infectious disease caused by Mycobacterium tuberculosis, which usually disturbs the lungs, and remains the second leading cause of death from an infectious disease worldwide after the human immunodeficiency virus. Herein, we constructed a simple and sensitive method for Mycobacterium tuberculosis-specific DNA detection with the dark-field microscopic imaging of gold nanoparticles (AuNPs) counting strategy and rolling-circle amplification (RCA). Taking advantage of RCA amplification, one target molecule produced hundreds of general oligonucleotides, which could form the sandwich structure with capture-strand-modified magnetic beads and AuNPs. After magnetic separation, AuNPs were released and detected by dark-field imaging; about 10 fM Mycobacterium tuberculosis-specific DNA target can still be differentiated from the blank. No significant change of the absorbance signals was observed when the target DNA to genomic DNA ratio (in mass) was from 1:0 to 1:10⁶. The spike recovery results in genomic DNA from human and Klebsiella pneumoniae suggested that the proposed method has the feasibility for application with biological samples. This proposed method is performed on an entry-level dark-field microscope setup with only a 6 μL detection volume, which creates a new, simple, sensitive, and valuable tool for pathogen detection.

Impact of on-site Xpert on TB diagnosis and mortality trends in Uganda

SETTING

Since 2012, Uganda expanded the Xpert® MTB/RIF network for diagnosis of TB.

OBJECTIVES

We compared TB care cascades at health facilities with on-site Xpert vs. facilities that accessed the assay through specimen referral.

DESIGN

We analysed secondary aggregate data of the National TB and Leprosy Program (NTLP) from 2016 to 2019. We computed the proportions of notified TB cases and mortality ratios in relation to the estimated TB burden.

RESULTS

TB case notifications per annum increased from 24,287 in 2016 to 30,739 in 2019, and the proportion of cases diagnosed at facilities with on-site Xpert testing increased from 62% (15,070/24,287) to 81% (24,829/30,739) (P < 0.001). TB mortality at facilities with on-site Xpert decreased from 8.6% (1,302/15,070) to 7.8% (1,938/24,829) (P = 0.41), while it increased at facilities without on-site Xpert from 6.9% (638/9,217) to 8.8% (521/5,910) (P = 0.23). Furthermore, mortality among TB-HIV co-infected patients at facilities with on-site Xpert dropped from 5.0% (760/15,070) in 2016 to 4.8% (1,187/24,826) in 2019 (P = 0.84) compared to 4.4% (407/9,217) in 2016 to 5.3% (315/5,910) in 2019 (P = 0.57).

CONCLUSION

Wider installation and decentralisation of Xpert leads to increased case-finding. However, the impact on reduction in mortality remains limited. Interventions to address TB-related mortality in addition to Xpert roll-out are required.

Exploring the role of Microbiome in Susceptibility, Treatment Response and Outcome among Tuberculosis Patients from Pakistan: study protocol for a prospective cohort study (Micro-STOP)

INTRODUCTION

Tuberculosis (TB) caused by Mycobacterium tuberculosis is a common infectious disease associated with significant morbidity and mortality, especially in low-income and middle-income countries. Successful treatment of the disease requires prolonged intake (6-8 months) of multiple antibiotics with potentially detrimental consequences on the composition and functional potential of the human microbiome. The protocol described in the current study aims to identify microbiome (oral and gut) signatures associated with TB pathogenesis, treatment response and outcome in humans.

METHODS AND ANALYSIS

Four hundred and fifty, newly diagnosed patients with TB from three district levels (Peshawar, Mardan and Swat) TB diagnosis and treatment centres, will be recruited in this non-interventional, prospective cohort study and will be followed and monitored until treatment completion. Demographic and dietary intake data, anthropometric measurement and blood, stool and salivary rinse samples will be collected at baseline, day 15, month-2 and end of the treatment. Additionally, we will recruit age (±3 years) and sex-matched healthy controls (n=30). Blood sampling will allow monitoring of the immune response during the treatment, while salivary rinse and faecal samples will allow monitoring of dynamic changes in oral and gut microbiome diversity. Within this prospective cohort study, a nested case-control study design will be conducted to assess perturbations in oral and gut microbiome diversity (microbial dysbiosis) and immune response and compare between the patients groups (treatment success vs failure).

ETHICS AND DISSEMINATION

The study has received ethics approval from the Ethic Board of Khyber Medical University Peshawar, and administrative approval from Provincial TB Control Programme of Khyber Pakhtunkhwa, Pakistan. The study results will be presented in national and international conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04985994.

Rapid Molecular Diagnosis of Extra-Pulmonary Tuberculosis by Xpert/RIF Ultra

Rapid detection of Mycobacterium tuberculosis complex and determination of drug resistance are essential for early diagnosis and treatment of tuberculosis (TB). Xpert MTB/RIF Ultra (Xpert Ultra), a molecular test that can simultaneously identify M. tuberculosis complex and resistance to rifampicin directly on clinical samples, is currently used. Xpert Ultra represents a helpful tool for rapid pulmonary TB diagnosis, especially in patients with paucibacillary infection. The aim of this review is to provide an overview of the diagnostic performance of Xpert Ultra in detection of extra-pulmonary tuberculosis.

Prevalence of rifampicin resistant tuberculosis among pulmonary tuberculosis patients In Enugu, Nigeria

OBJECTIVE

We determined the prevalence of rifampicin resistance in pulmonary tuberculosis patients in Enugu Nigeria.

METHODS

A prospective hospital-based study involving 1300 presumptive multidrug-resistant tuberculosis patients was conducted in Enugu between April 2017 and 31st March, 2019.Participants age ranged from 15 years and older and each submitted one sputum specimens Sputum specimens were analyzed using the Gene Xpert MTB/RIF assay to detect resistance to rifampicin according to manufacturer's protocol.

RESULTS

The prevalence of rifampicin resistant tuberculosis was 6.8% (95% CI: 5.5- 8.3). Rifampicin resistance was significantly higher in males (9.0%) than females (4.2%) (P = 0.036< 0.05). Most of the cases were seen in the age group 35-44 years (28.4%). Prevalence of rifampicin resistant tuberculosis was 2.7% in treatment naive (new) patients and 4.1% in patients on anti-tuberculosis therapy (previously treated).

CONCLUSION

The prevalence of rifampicin resistant tuberculosis in Enugu was high. Rifampicin resistance in treatment naive (new) patients was also high. This study therefore highlights that active transmission of Multidrug-resistant tuberculosis among young males could be on-going.

Rapid Detection of MCR-Mediated Colistin Resistance in Escherichia coli

Colistin is one of the last-resort antibiotics for infections caused by multidrug-resistant Gram-negative bacteria. However, the wide spread of novel plasmid-carrying colistin resistance genes mcr-1 and its variants substantially compromise colistin's therapeutic effectiveness and pose a severe danger to public health. To detect colistin-resistant microorganisms induced by mcr genes, rapid and reliable antibiotic susceptibility testing (AST) is imminently needed. In this study, we identified an RNA-based AST (RBAST) to discriminate between colistin-susceptible and mcr-1-mediated colistin-resistant bacteria. After short-time colistin treatment, RBAST can detect differentially expressed RNA biomarkers in bacteria. Those candidate mRNA biomarkers were successfully verified within colistin exposure temporal shifts, concentration shifts, and other mcr-1 variants. Furthermore, a group of clinical strains were effectively distinguished by using the RBAST approach during the 3-h test duration with over 93% accuracy. Taken together, our findings imply that certain mRNA transcripts produced in response to colistin treatment might be useful indicators for the development of fast AST for mcr-positive bacteria.

IMPORTANCE The emergence and prevalence of mcr-1 and its variants in humans, animals, and the environment pose a global public health threat. There is a pressing urgency to develop rapid and accurate methods to identify MCR-positive colistin-resistant bacteria in the clinical samples, providing a basis for subsequent effective antibiotic treatment. Using the specific mRNA signatures, we develop an RNA-based antibiotic susceptibility testing (RBAST) for effectively distinguishing colistin-susceptible and mcr-1-mediated colistin-resistant strains. Meanwhile, the detection efficiency of these RNA biomarkers was evidenced in other mcr variants-carrying strains. By comparing with the traditional AST method, the RBAST method was verified to successfully characterize a set of clinical isolates during 3 h assay time with over 93% accuracy. Our study provides a feasible method for the rapid detection of colistin-resistant strains in clinical practice.

Application of core needle biopsy in the diagnosis of epididymal tuberculosis: a retrospective analysis of 41 cases

OBJECTIVE

We aimed to investigate the use of core needle biopsy (CNB) in epididymal tuberculosis (TB) diagnosis.

METHODS

We analyzed 41 samples collected between January 1, 2018, and January 31, 2021, from patients who underwent CNB for suspected epididymal TB. All specimens were examined using histopathological examination and the Xpert Mycobacterium tuberculosis bacilli/rifampicin (MTB/RIF) assay. We analyzed the examination results to determine the application value of CNB in epididymal TB diagnosis and evaluate its safety.

RESULTS

According to the comprehensive reference standard established in this study, 37 of the 41 patients had epididymal TB and four patients had chronic epididymitis. The sensitivity, specificity, positive predictive value, negative predictive value, and area under the curve of histopathological examination were 86.49% (71.23-95.46%), 100.00% (39.76-100.00%), 100.00% (89.11-100.00%), 44.44% (13.70-78.80%), and 0.93 (0.81-0.99), respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and area under the curve of the Xpert MTB/RIF assay were 62.16% (44.76-77.54%), 100.00% (39.76-100.00%), 100.00% (85.18-100.00%), 22.22% (6.41-47.76%), and 0.81 (0.66-0.92), respectively. No postoperative complication attained a Clavien-Dindo classification grade of >2.

CONCLUSION

CNB was useful in diagnosing epididymal TB. Therefore, we recommend using CNB as a sample collection tool for diagnosing epididymal TB.

Diagnosis of Mycobacterium tuberculosis using GeneXpert MTB / RIF and TB-LAMP techniques from pulmonary and extra-pulmonary TB patients in Iraq

Tuberculosis is considered one globally public health problem, particularly in unindustrialized countries. The disease has an increasing threat to public health, causing high morbidity and mortality rates. So, rapid diagnosis is critical to diminish the death and interfere with transmission. In this study, GeneXpert MTB/RIF and Loop-Mediated Isothermal Amplification (TB-LAMP) assays were utilized for the rapid molecular diagnosis of Mycobacterium tuberculosis bacteria and compared sensitivity and specificity of Mycobacterium tuberculosis bacteria; these tests with acid-fast bacilli staining in pulmonary and extra-pulmonary clinical specimens from Iraqi patients in Baghdad capital. 141 pulmonary and extra-pulmonary samples were collected and tested for tuberculosis detection. Acid-fast bacilli, TB-LAMP and GeneXpert MTB/RIF methods were used to diagnose tuberculosis. Of 141 tuberculosis specimens, 58 were acid-fast bacilli smear-positive, while 90 samples were positive for Mycobacterium tuberculosis by GeneXpert MTB/RIF assay and 78 by TB-LAMP assay. The results reported a high sensitivity rate of GeneXpert MTB/RIF assay compared to the TB-LAMP and bacilli staining method. The sensitivity of GeneXpert was 63.83%, specificity 50%; positive and negative predictive values were 58.36% to 68.96% and 42.73% to 57.27%, respectively. TB-LAMP sensitivity was 55.32%, specificity 50%; positive and negative predictive values were 49.61% to 60.89% and 43.70% to 56.30%, respectively, while the sensitivity of bacilli staining was 41.13%, specificity 50%; positive and negative predictive values were 35.26% to 47.27% and 44.88% to 55.12%, respectively, these values are dependent on disease prevalence. We concluded that the GeneXpert MTB/RIF test is more sensitive and specific than the TB-LAMP and both techniques are more sensitive and specific than the conventional acid-fast staining method for both pulmonary and extra-pulmonary specimens. Despite culture remaining the gold standard for laboratory confirmation of TB, GeneXpert MTB/RIF and TB-LAMP should become standard practice for patients with suspected TB, and all clinicians and public health programs for TB control should have access to molecular testing for TB to shorten diagnosis time. Keywords. Mycobacterium tuberculosis; Pulmonary TB; Extrapulmonary TB; GeneXpert MTB/RIF; TB-LAMP; A.F.B

Drug-resistant tuberculosis: advances in diagnosis and management

PURPOSE OF REVIEW

Diagnosis and treatment of drug-resistant tuberculosis (DR-TB) is undergoing substantial changes, owing availability of new diagnostic tools and drugs, coupled with global underdiagnosis and undertreatment. Recent developments are reviewed.

RECENT FINDINGS

Molecular diagnostics, for Mycobacterium tuberculosis complex detection and prediction of drug resistance, implemented in the last decade, accelerated TB diagnosis with improved case detection. Nevertheless, access and coverage of drug-resistance testing remain insufficient. Genome sequencing-technologies, based on targeted next-generation sequencing show early potential to mitigate some of the challenges in the future. The recommendation to use an all oral, bedaquiline based regimen for treatment of multidrug-resistant/rifampicin-resistant TB is major advancement in DR-TB care. TB regimen using new and repurposed TB drugs demonstrate in recent clinical trials like, NIX-TB, ZeNIX and TB PRACTECAL considerable treatment success, shorten treatment duration and reduce toxicity. Their optimal use is threatened by the rapid occurrence and spread of strains, resistant to new drugs. Children benefit only very slowly from the progress.

SUMMARY

There is notable progress in improved diagnosis and treatment of drug-resistant TB, but complicated by the COVID-19 pandemic the majority of TB patients worldwide don't have (yet) access to the advances.

Predicting the risk of active pulmonary tuberculosis in people living with HIV: development and validation of a nomogram

BACKGROUND

Diagnosis of pulmonary tuberculosis (PTB) among people living with HIV (PLHIV) was challenging. The study aimed to develop and validated a simple, convenient screening model for prioritizing TB among PLHIV.

METHODS

The study included eligible adult PLHIV participants who attended health care in Yunnan, China, from January 2016 to July 2019. Participants included before June 2018 were in the primary set; others were in the independent validation set. The research applied the least absolute shrinkage and selection operator regression to identify predictors associated with bacteriological confirmed PTB. The TB nomogram was developed by multivariate logistic regression. The C-index, receiver operating characteristic curve (ROC), the Hosmer-Lemeshow goodness of fit test (H-L), and the calibration curves were applied to evaluate and calibrate the nomogram. The developed nomogram was validated in the validation set. The clinical usefulness was assessed by cutoff analysis and decision curve analysis in the primary set.

RESULT

The study enrolled 766 PLHIV, of which 507 were in the primary set and 259 in the validation set, 21.5% and 14.3% individuals were confirmed PTB in two sets, respectively. The final nomogram included 5 predictors: current CD 4 cell count, the number of WHO screen tool, previous TB history, pulmonary cavity, and smoking status (p < 0.05). The C-statistic was 0.72 (95% CI 0.66-0.77) in primary set and 0.68 (95% CI 0.58-0.75) in validation set, ROC performed better than other models. The nomogram calibration was good (H-L χ² = 8.14, p = 0.15). The area under the decision curve (0.025) outperformed the existing models. The optimal cutoff for screening TB among PLHIV was the score of 100 (sensitivity = 0.93, specificity = 0.35).

CONCLUSION

The study developed and validated a discriminative TB nomogram among PLHIV in the moderate prevalence of TB and HIV. The easy-to-use and straightforward nomogram would be beneficial for clinical practice and rapid risk screening in resource-limited settings.

Drug resistant tuberculosis: Current scenario and impending challenges

Tuberculosis is still one of the ten leading causes for death worldwide. In spite of the latest medical and health advance gained over a period of time, tuberculosis effectively evades the successful targeting by drugs. The persistence abilities demonstrated by the mycobacteria had surprised the global community, since its discovery and pathogenesis in humans. Emergence and detection of drug resistant mycobacteria (MDR-TB, XDR-TB) had further complicated the treatment regime. Under the aegis of WHO, there is a concerted understanding and effort by the global community to eradicate TB. Towards this goal, novel drug molecules, new vaccine and treatment regime are being developed. Here, our current understanding pertaining to mode of action, molecular mechanisms of novel as well as traditional drug molecules and possible drug resistance mechanism in M. Tuberculosis is reviewed. Recent advances on new vaccination regime are also reviewed as it demonstrated huge potential in containing TB. This knowledge is essential for the development of more effective drug molecules, vaccines and may help in devising new strategy for containing and eradicating TB.

Establishment and evaluation of an overlap extension polymerase chain reaction technique for rapid and efficient detection of drug-resistance in Mycobacterium tuberculosis

BACKGROUND

Rapid and accurate detection of drug resistance in Mycobacterium tuberculosis is critical for effective control of tuberculosis (TB). Herein, we established a novel, low cost strategy having high accuracy and speed for the detection of M. tuberculosis drug resistance, using gene splicing by overlap extension PCR (SOE PCR).

METHODS

The SOE PCR assay and Sanger sequencing are designed and constructed to detect mutations of rpoB, embB, katG, and inhA promoter, which have been considered as the major contributors to rifampicin (RFP), isoniazid (INH), and ethambutol (EMB) resistance in M. tuberculosis. One hundred and eight M. tuberculosis isolates came from mycobacterial cultures of TB cases at Chongqing Public Health Medical Center in China from December 2018 to April 2019, of which 56 isolates were tested with the GeneXpert MTB/RIF assay. Performance evaluation of the SOE PCR technique was compared with traditional mycobacterial culture and drug susceptibility testing (DST) or GeneXpert MTB/RIF among these isolates. Kappa identity test was used to analyze the consistency of the different diagnostic methods.

RESULTS

We found that the mutations of S531L, S315T and M306V were most prevalent for RFP, INH and EMB resistance, respectively, in the 108 M. tuberculosis isolates. Compared with phenotypic DST, the sensitivity and specificity of the SOE PCR assay for resistance detection were 100.00% and 88.00% for RFP, 94.64% and 94.23% for INH, and 68.97% and 79.75% for EMB, respectively. Compared with the GeneXpert MTB/RIF, the SOE PCR method was completely consistent with results of the GeneXpert MTB/RIF, with a concordance of 100% for resistance to RFP.

CONCLUSIONS

In present study, a novel SOE PCR diagnostic method was successfully developed for the accurate detection of M. tuberculosis drug resistance. Our results using this method have a high consistency with that of traditional phenotypic DST or GeneXpert MTB/RIF, and SOE PCR testing in clinical isolates can also be conducted rapidly and simultaneously for detection of drug resistance to RFP, EMB, and INH.

Diagnostic Advances in Childhood Tuberculosis—Improving Specimen Collection and Yield of Microbiological Diagnosis for Intrathoracic Tuberculosis

There is no microbiological gold standard for childhood tuberculosis (TB) diagnosis. The paucibacillary nature of the disease, challenges in sample collection in young children, and the limitations of currently available microbiological tests restrict microbiological confirmation of intrathoracic TB to the minority of children. Recent WHO guidelines recommend the use of novel rapid molecular assays as initial diagnostic tests for TB and endorse alternative sample collection methods for children. However, the uptake of these tools in high-endemic settings remains low. In this review, we appraise historic and new microbiological tests and sample collection techniques that can be used for the diagnosis of intrathoracic TB in children. We explore challenges and possible ways to improve diagnostic yield despite limitations, and identify research gaps to address in order to improve the microbiological diagnosis of intrathoracic TB in children.

GeneXpert: A Rapid and Supplementary Diagnostic Tool for Tuberculous Meningitis, Experience from Tertiary Neurocenter

Background  Tuberculous meningitis (TBM) is a highly lethal form of central nervous system tuberculosis (CNS TB) that causes high mortality and morbidity in children and adults. Nonspecific clinical presentation and fewer TB bacilli challenge clinicians resulting in delays in diagnosis and treatment.

Aim  This study aimed to evaluate the utility of GeneXpert alone and in combination with culture using 1 mL of cerebrospinal fluid (CSF) in a volume constraint situation.

Methods  A total of 125 clinically confirmed TBM and 110 non-TBM cases, comprised of both infectious and noninfectious diseases. were included in the study. Patient details including clinical signs and symptoms, CSF, and imaging data were collected from the case records. CSF samples were obtained from all the patients and were tested by the mycobacterial culture method and GeneXpert test. The performance of both the tests was statistically calculated and reported in the form of sensitivity and specificity.

Results  Out of 125 TBM cases, 40 were detected positive by culture and 26 by GeneXpert. All 110 non-TBM cases were identified negative by both methods. The sensitivity and specificity of GeneXpert in comparison with culture were 27 and 100%, respectively. The culture was found to be more sensitive (32%) than GeneXpert. But the assay was able to detect a considerable number of clinically confirmed culture-negative TBM cases.

Conclusion  GeneXpert is a rapid test and including this as an adjunctive test along with the culture in routine clinical practice can improve the diagnosis of TBM in volume constraint scenario.

Development and validation of a multiplex real-time qPCR assay using GMP-grade reagents for leprosy diagnosis

Leprosy is a chronic dermato-neurological disease caused by Mycobacterium leprae, an obligate intracellular bacterium. Timely detection is a challenge in leprosy diagnosis, relying on clinical examination and trained health professionals. Furthermore, adequate care and transmission control depend on early and reliable pathogen detection. Here, we describe a qPCR test for routine diagnosis of leprosy-suspected patients. The reaction simultaneously amplifies two specific Mycobacterium leprae targets (16S rRNA and RLEP), and the human 18S rRNA gene as internal control. The limit of detection was estimated to be 2.29 copies of the M. leprae genome. Analytical specificity was evaluated using a panel of 20 other skin pathogenic microorganisms and Mycobacteria, showing no cross-reactivity. Intra- and inter-operator C_p variation was evaluated using dilution curves of M. leprae DNA or a synthetic gene, and no significant difference was observed between three operators in two different laboratories. The multiplex assay was evaluated using 97 patient samples with clinical and histopathological leprosy confirmation, displaying high diagnostic sensitivity (91%) and specificity (100%). Validation tests in an independent panel of 50 samples confirmed sensitivity and specificity of 97% and 98%, respectively. Importantly, assay performance remained stable for at least five months. Our results show that the newly developed multiplex qPCR effectively and specifically detects M. leprae DNA in skin samples, contributing to an efficient diagnosis that expedites the appropriate treatment.

Leprosy is a chronic dermato-neurological disease caused by Mycobacterium leprae, an obligate intracellular bacterium. Diagnosis of leprosy often relies on skin examinations for clinical signs, bacilli staining from skin smears and invasive skin biopsies. However, the spectrum of clinical manifestations and, often, low bacilli numbers can hinder accurate diagnosis. Timely detection is a challenge in leprosy diagnosis, relying on clinical examination and requiring trained health professionals. Proper intervention for adequate care and transmission control depends on early and reliable pathogen detection. Quantitative PCR methods for detecting bacterial DNA are more sensitive and could aid in differentially diagnosing leprosy from other dermatological conditions. In this work, we present a new multiplex PCR that was assessed for quality control standards, and the data indicate that the assay is stable and reproducible. The results presented here are the basis of a novel and robust tool with potential to increase the accuracy of leprosy diagnosis in routine or reference laboratories.

Culture-Free Enumeration of Mycobacterium tuberculosis in Mouse Tissues Using the Molecular Bacterial Load Assay for Preclinical Drug Development

Background: The turnaround times for phenotypic tests used to monitor the bacterial load of Mycobacterium tuberculosis, in both clinical and preclinical studies, are delayed by the organism’s slow growth in culture media. The existence of differentially culturable populations of M.tuberculosis may result in an underestimate of the true number. Moreover, culture methods are susceptible to contamination resulting in loss of critical data points. Objectives: We report the adaptation of our robust, culture-free assay utilising 16S ribosomal RNA, developed for sputum, to enumerate the number of bacteria present in animal tissues as a tool to improve the read-outs in preclinical drug efficacy studies. Methods: Initial assay adaptation was performed using naïve mouse lungs spiked with known quantities of M. tuberculosis and an internal RNA control. Tissues were homogenised, total RNA extracted, and enumeration performed using RT-qPCR. We then evaluated the utility of the assay, in comparison to bacterial counts estimated using growth assays on solid and liquid media, to accurately inform bacterial load in tissues from M. tuberculosis-infected mice before and during treatment with a panel of drug combinations. Results: When tested on lung tissues derived from infected mice, the MBL assay produced comparable results to the bacterial counts in solid culture (colony forming units: CFU). Notably, under specific drug treatments, the MBL assay was able to detect a significantly higher number of M. tuberculosis compared to CFU, likely indicating the presence of bacteria that were unable to produce colonies in solid-based culture. Additionally, growth recovery in liquid media using the most probable number (MPN) assay was able to account for the discrepancy between the MBL assay and CFU number, suggesting that the MBL assay detects differentially culturable sub-populations of M. tuberculosis. Conclusions: The MBL assay can enumerate the bacterial load in animal tissues in real time without the need to wait for extended periods for cultures to grow. The readout correlates well with CFUs. Importantly, we have shown that the MBL is able to measure specific populations of bacteria not cultured on solid agar. The adaptation of this assay for preclinical studies has the potential to decrease the readout time of data acquisition from animal experiments and could represent a valuable tool for tuberculosis drug discovery and development.

Performance of WHO-Endorsed Rapid Tests for Detection of Susceptibility to First-Line Drugs in Patients with Pulmonary Tuberculosis in Bangladesh

The fast and accurate detection of susceptibility in drugs is a major challenge for a successful tuberculosis (TB) control programme. This study evaluated the performance of WHO-endorsed rapid diagnostic tools, such as BACTEC MGIT 960 SIRE (MGIT SIRE), GenoType MTBDRplus (MTBDRplus) and Xpert MTB/RIF (Xpert), for detecting susceptibility to first-line anti-TB drugs among pulmonary TB patients in Bangladesh. A total of 825 sputum samples with results from drug susceptibility testing (DST) against first-line anti-TB drugs in the MGIT SIRE, MTBDRplus and Xpert assays were evaluated and compared with the gold standard proportion susceptibility method of the Lowenstein–Jensen (LJ) medium. The overall sensitivities of MGIT SIRE were 97.6%, 90.0%, 61.3% and 44.9%, while specificities were 89.9%, 94.5%, 91.3% and 92.2% for detection of susceptibility to isoniazid (INH), rifampicin (RIF), streptomycin (STR) and ethambutol (EMB), respectively. For MTBDRplus, the sensitivities were 88.0% and 88.7%, and the specificities were 97.4% and 97.8% for the detection of susceptibility to INH and RIF, respectively. Xpert demonstrated a sensitivity and specificity of 94.8% and 99.5%, respectively, for the detection of RIF susceptibility. All tests performed significantly better in retreated TB patients compared with primary TB cases. For detection of RIF and INH susceptibility, all three assays showed almost perfect agreement with the LJ method, although MGIT SIRE exhibited low agreement for STR and EMB. Considering the high performance, shorter turnaround time and ease of use, molecular-based approaches Xpert and MTBDRplus can be widely implemented throughout the country for the rapid detection of drug-resistant TB.

The Structural Basis of Mycobacterium tuberculosis RpoB Drug-Resistant Clinical Mutations on Rifampicin Drug Binding

Tuberculosis (TB), caused by the Mycobacterium tuberculosis infection, continues to be a leading cause of morbidity and mortality in developing countries. Resistance to the first-line anti-TB drugs, isoniazid (INH) and rifampicin (RIF), is a major drawback to effective TB treatment. Genetic mutations in the β-subunit of the DNA-directed RNA polymerase (rpoB) are reported to be a major reason of RIF resistance. However, the structural basis and mechanisms of these resistant mutations are insufficiently understood. In the present study, thirty drug-resistant mutants of rpoB were initially modeled and screened against RIF via a comparative molecular docking analysis with the wild-type (WT) model. These analyses prioritized six mutants (Asp441Val, Ser456Trp, Ser456Gln, Arg454Gln, His451Gly, and His451Pro) that showed adverse binding affinities, molecular interactions, and RIF binding hinderance properties, with respect to the WT. These mutant models were subsequently analyzed by molecular dynamics (MD) simulations. One-hundred nanosecond all-atom MD simulations, binding free energy calculations, and a dynamic residue network analysis (DRN) were employed to exhaustively assess the impact of mutations on RIF binding dynamics. Considering the global structural motions and protein-ligand binding affinities, the Asp441Val, Ser456Gln, and His454Pro mutations generally yielded detrimental effects on RIF binding. Locally, we found that the electrostatic contributions to binding, particularly by Arg454 and Glu487, might be adjusted to counteract resistance. The DRN analysis revealed that all mutations mostly distorted the communication values of the critical hubs and may, therefore, confer conformational changes in rpoB to perturb RIF binding. In principle, the approach combined fundamental molecular modeling tools for robust "global" and "local" level analyses of structural dynamics, making it well suited for investigating other similar drug resistance cases.

Precision Medicine in Low- and Middle-Income Countries

Most cancer cases occur in low- and middle-income countries (LMICs). The sophisticated technical and human infrastructure needed for optimal diagnosis, treatment, and monitoring of cancers is difficult enough in affluent countries; it is especially challenging in LMICs. In Western, educated, industrial, rich, democratic countries, there is a growing emphasis on and success with precision medicine, whereby targeted therapy is directed at cancers based on the specific genetic lesions in the cancer. Can such precision approaches be delivered in LMICs? We offer some examples of novel partnerships and creative solutions that suggest that precision medicine may be possible in LMICs given heavy doses of will, creativity, and persistence and a little luck.

Multiple Cross Displacement Amplification Combined With Real-Time Polymerase Chain Reaction Platform: A Rapid, Sensitive Method to Detect Mycobacterium tuberculosis

In this study, we evaluated the diagnostic accuracy of multiple cross displacement amplification (MCDA) combined with real-time PCR platform in pulmonary tuberculosis (PTB) patients. Total 228 PTB patients and 141 non-TB cases were enrolled. Based on the analysis of the first available sample of all participants, MCDA assay showed a higher overall sensitivity (64.0%), with a difference of more than 10% compared with Xpert MTB/RIF (Xpert) assay (51.8%, P < 0.05) and combined liquid and solid culture (47.8%, P < 0.001) for PTB diagnosis. In particular, MCDA assay detected 31 probable TB patients, which notably increased the percentage of confirmed TB from 57.9% (132/228) to 71.5% (163/228). The specificities of microscopy, culture, Xpert and MCDA assay were 100% (141/141), 100% (141/141), 100% (141/141), and 98.6% (139/141), respectively. Among the patients with multiple samples, per patient sensitivity of MCDA assay was 60.5% (52/86) when only the first available sputum sample was taken into account, and the sensitivity increased to 75.6% (65/86) when all samples tested by MCDA assay were included into the analysis. Therefore, MCDA assay established in this study is rapid, accurate and affordable, which has the potential in assisting the accurate and rapid diagnosis of PTB and speed up initiation of TB treatment in settings equipped with real-time PCR platform.

Clinical Validation of the Xpert MTB/RIF test for Identification of the MTB Complex in AFB Smear-Positive MGIT broth cultures

The identification of the M. tuberculosis complex (MTBC) from smear positive broth cultures can be achieved using several methods including both lab-developed and commercially available molecular assays. In the United States, a commercially available probe-based assay has been used for over a decade by many laboratories for identification of MTBC directly from AFB smear positive broth cultures, including those recovered from the MGIT 960 system. However, recent difficulties in obtaining probe kits for identification resulted in mycobacteriology laboratories looking for alternative platforms to provide for rapid identification of MTBC and detection of rifampicin resistance. The Xpert® MTB/RIF test (Cepheid, Sunnyvale, Ca) has shown high sensitivity for the diagnosis of MTBC from pulmonary specimens but is not often used for identification directly from smear positive, MGIT 960 broth cultures (Becton Dickinson, Sparks, Md). We sought to validate the Xpert MTB/RIF test for use with AFB smear positive MGIT 960 cultures in a clinical hospital setting. Overall, the assay showed a categorical agreement of 100% for identification of MTBC and detection of rifampin resistance. No false positive results or cross-reactivity were noted. Findings indicate that the Xpert MTB/RIF test may be suitable as a rapid replacement for identification of MTBC and detection of rifampicin resistance from AFB smear positive MGIT 960 broth cultures.

Interaction of Host Pattern Recognition Receptors (PRRs) with Mycobacterium Tuberculosis and Ayurvedic Management of Tuberculosis: A Systemic Approach

Tuberculosis (TB), an infectious disease caused by Mycobacterium tuberculosis (Mtb), infects the lungs' alveolar surfaces through aerosol droplets. At this stage, the disease progression may have many consequences, determined primarily by the reactions of the human immune system. However, one approach will be to more actively integrate the immune system, especially the pattern recognition receptor (PRR) systems of the host, which notices pathogen-associated molecular patterns (PAMPs) of Mtb. Several types of PRRs are involved in the detection of Mtb, including Toll-like receptors (TLRs), C-type lectin receptors (CLRs), Dendritic cell (DC) -specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN), Mannose receptor (MR), and NOD-like receptors (NLRs) related to inflammasome activation. In this study, we focus on reviewing the Mtb pathophysiology and interaction of host PPRs with Mtb as well as adverse drug effects of anti-tuberculosis drugs (ATDs) and systematic TB treatment via Ayurvedic medicine.

Role of GeneXpertMTB/RIF in the diagnosis of cutaneous tuberculosis

BACKGROUND

cutaneous involevemtn is an important extrapulmonary manifestation of tuberculosis. It is a paucibacillary condition and has diverse clinical presentations. Sufficient data is not available regarding role of GeneXpertMTB/RIF in cutanoues tuberculosis.

METHODS

in this study, BacT/Alert3D and response to antitubercular therapy were taken as gold standard and performance of GeneXpertMTB/RIF was evaluated against it in clinically and histopathologically suspected cases of cutaneous tuberculosis.

RESULTS

forty seven patients were included in the study of which commonest presentation was scrofuloderma (42.6%) followed by lupus vulgaris (40.4%). Granulomatous inflammation on histopathology was seen in 75.5% patients on skin biopsy. Sic patients had extracutaneous focus of tuberculosis. In 14 (29.79%), culture of skin biopsy was positive for M. tuberculosis and all showed complete response to ATT in 6 months. GeneXpertMTB/RIF detected M. tuberculsois in 4 samples.

CONCLUSION

GeneXpertMTB/RIF is not a reliable tool for diagnosis of cutaneous tuberculosis. Clinic-histopathological correlation along with response to ATT is needed for confirmation of diagnosis of cutaneous tuberculosis.

Tuberculosis in Cirrhosis - A Diagnostic and Management Conundrum

Background

Diagnosis and management of tuberculosis (TB) in patients with cirrhosis remains challenging. We studied the clinical spectrum, diagnosis, and management of TB along with the assessment of the diagnostic utility of various laboratory investigations in this cohort.

Methods

A retrospective review of records of patients with cirrhosis (July 2017 and December 2019) was done. Out of 30 patients with cirrhosis and TB, 20 patients with pleural/peritoneal TB (cases) were compared with 20 consecutively selected spontaneous bacterial peritonitis (SBP) controls. Composite of clinical, laboratory, radiologic features and response to antituberculosis therapy (ATT) was taken as the gold standard to diagnose TB.

Results

Extrapulmonary TB (EPTB) (n = 23, 76.7%) was more common. Overall, 9 (30%) patients presented with ATT-induced hepatitis. Patients with pleural/peritoneal TB had less severe hepatic dysfunction as compared to SBP group with significantly lower CTP [8 ± 1.5 vs. 9 ± 1.7 (P = 0.01)], MELD [16.3 ± 5.8 vs. 20.2 ± 6.6 (P = 0.02)] and MELD-Na [18.8 ± 5.9 vs. 22.5 ± 7.1 (P = 0.03)] scores. Median ascitic/pleural fluid total protein [2.7 (2.4-3.1) vs. 1.1 (0.9-1.2); P < 0.0001] and adenosine deaminase (ADA) levels [34.5 (30.3-42.7) vs. 15 (13-16); P < 0.0001] were significantly higher in the TB group. Total protein levels had a sensitivity and specificity 81% and 93.3%, respectively, at cut off value of >2 g/dl with an AUROC of 0.89 [(0.79-0.96); P < 0.001] whereas ADA levels at cutoff >26 IU/L showed 80% sensitivity and 90% specificity to diagnose pleural/peritoneal TB with an AUROC of 0.93 [(0.82-0.97); P < 0.001]. Only 11 (36.7%), and 8 (26.6%) patients showed positivity on GeneXpert and mTB-PCR, respectively. Patients with Child-Turcotte-Pugh scores of ≤7 and 8-10 tolerated well two and one hepatotoxic drugs, respectively.

Conclusions

EPTB is more frequent in patients with cirrhosis. Relatively lower cutoffs of ascitic/pleural fluid total protein and ADA may be useful to diagnose EPTB in patients with high pretest probability. Individualized ATT with close monitoring and dynamic modifications is effective and well-tolerated.

Status of drug resistant tuberculosis among patients attending a tuberculosis unit of West Bengal: A record based cross-sectional study

Context

Tuberculosis (TB) is one of the main causes of death due to infectious diseases worldwide. Multidrug resistance/rifampicin resistance (MDR/RR) TB remains a public health crisis. India has the highest burden of tuberculosis and multidrug resistant TB (MDR TB) in the world. There is wide geographical variation in the epidemic and its trends that can be updated by regular reporting and sound surveillance systems. The current study tries to fill this gap by analyzing the data of TB patients from a Tuberculosis Unit, studying socio-demographic and clinical profile from December 2017 to November 2019 in Nadia district of West Bengal.

Aims

The aims of this work were to study socio-demographic and clinical profile of TB patients attending Tuberculosis Unit of West Bengal, and to find out factors associated with drug-resistant TB.

Settings and Design

Record-based study from Tuberculosis Unit.

Methods

Records of all patients who undergo CBNAAT in TU are stored as monthly unit. We randomly selected 10 months from a period of December 2017 to November 2019 by using lot method. Data of all patients undergoing CBNAAT at Kalyani - Gayeshpur Tuberculosis Unit during randomly selected 10 months were accessed.

Statistical Analysis Used

Monthly data was entered in Microsoft Excel and descriptive tests of significance, proportions and Chi-square were applied.

Results

There was male preponderance for testing of tuberculosis. Seven percent of the TB suspects were HIV positive. The positivity rate of MTB by CBNAAT was 23%. Four percent of the samples were Rifampicin resistance. Tobacco consumption, contact with TB case and Diabetes were common risk factors of TB. Most of the information was missing in the records.

Conclusions

Most of Rifampicin Resistant cases showed very low Ct value in CBNAAT. Previous history of TB treatment and positive HIV status was significantly associated with RR TB. There is a need to capture complete information on the records of presumptive TB cases.

Diagnostic accuracy of Truenat Tuberculosis and Rifampicin-Resistance assays in Addis Ababa, Ethiopia

BACKGROUND

Rapid and sensitive Tuberculosis (TB) diagnosis closer to patients is a key global TB control priority. Truenat assays (MTB, MTB Plus, and MTB-RIF Dx) are new TB molecular diagnostic tools for the detection of TB and Rifampicin (RIF)-resistance from sputum samples. The diagnostic accuracy of the assays is needed prior to implementation in clinical use in Ethiopia. This study aimed to determine the sensitivity and specificity of Truenat assays; and aimed to compare the assays to the Xpert MTB/RIF assay.

METHODS

A prospective evaluation study was conducted among 200 presumptive TB patients in microscopy centers in Addis Ababa, Ethiopia from May 2019 to December 2020. Culture (Solid and Liquid methods) and phenotypic (liquid method) drug susceptibility testing (DST) were used as a reference standard.

RESULTS

Of 200 adult participants, culture confirmed TB cases were 25 (12.5%), and only one isolate was resistant to RIF by phenotypic DST. The sensitivity of Truenat MTB was 88.0% [95% CI 70.1, 95.8], while 91.7 [95% CI 74.2, 97.7] for Truenat MTB Plus at the microscopy centers. The specificity of Truenat MTB was 97.2% [95% CI 93.1, 98.9], while for Truenat MTB Plus was 97.2% [95% CI 93.0, 99.0]. The sensitivity of Truenat MTB was 90.5% while for MTB Plus, 100% compared to the Xpert MTB/RIF assay.

CONCLUSION

Truenat assays were found to have high diagnostic accuracy. The assays have the potential to be used as a point of care (POC) TB diagnostic tests.

Clinical Features, Histopathology and Differential Diagnosis of Sarcoidosis

Sarcoidosis is a chameleon disease of unknown etiology, characterized by the growth of non-necrotizing and non-caseating granulomas and manifesting with clinical pictures that vary on the basis of the organs that are mainly affected. Lungs and intrathoracic lymph nodes are the sites that are most often involved, but virtually no organ is spared from this disease. Histopathology is distinctive but not pathognomonic, since the findings can be found also in other granulomatous disorders. The knowledge of these findings is important because it could be helpful to differentiate sarcoidosis from the other granulomatous-related diseases. This review aims at illustrating the main clinical and histopathological findings that could help clinicians in their routine clinical practice.

Effectiveness of GeneXpert® in the diagnosis of tuberculosis in people living with HIV/AIDS

OBJECTIVE

To identify and synthesize the scientific knowledge produced regarding the effectiveness of the GeneXpert test in the diagnosis of pulmonary tuberculosis (TB) in people living with HIV/AIDS.

METHODS

Integrative literature review, which was searched on Embase, Scopus, PubMed, Cinahl, Academic Search Premier, Socindex, and LILACS platforms, in December 2019. The studies surveyed went through two stages of selection: reading of titles and abstracts by two reviewers independently; using the Rayyan platform and reading. Nineteen primary studies in English, Portuguese, and Spanish that answered the study's guiding question were included: How effective is the GeneXpert test in the diagnosis of pulmonary TB in people living with HIV/AIDS?

RESULTS

The use of GeneXpert substantially increased the detection of TB cases among the population co-infected with HIV/AIDS, with sensitivity ranging from 68% to 100%, superior to sputum smear microscopy. Specificity ranged from 91.7% to 100%; the positive predictive value from 79.2% to 96.1%; and the negative predictive value from 84.6% to 99.3%. These values were considered similar to sputum smear microscopy by most studies. We also compared these results with different ways of performing culture and other molecular tests, being considered inferior only to the Xpert Ultra.

CONCLUSION

It is possible to affirm that places with a high incidence of HIV/AIDS would benefit from the implementation of the GeneXpert test, entailing effectiveness in diagnosing pulmonary TB in this population when compared to sputum smear microscopy, a widely used test for detection of cases.

Epidemiological profile of multidrug-resistant and extensively drug-resistant Mycobacterium Tubrculosis among Congolese patients

BACKGROUND

There is paucity of data on the prevalence and distribution of multidrug- Resistant-Tuberculosis (MDR-TB) in the Republic of Congo. Among the challenges resides the implementation of a robust TB resistance diagnostic program using molecular tools. In resource limited settings there is a need to gather data to enable prioritization of actions. The objective of this study was is to implement molecular tools as a best of diagnosing MDR and XDR-TB among presumptive tuberculosis patients referred to reference hospital of Makelekele in Brazzaville, Republic of the Congo.

METHODS

We have conducted a cross-sectional study, including a total of 92 presumptive pulmonary tuberculosis patients and who had never received treatment recruited at the reference hospital of Makelekele from October 2018 to October 2019. The socio-demographic and clinical data were collected as well as sputum samples. Rifampicin resistance was investigated using Xpert (Cepheid) and second-line TB drugs Susceptibility testing were performed by the Brucker HAIN Line Probe Assay (GenoType MTBDRsl VER 2.0 assay) method.

RESULTS

From the 92 recruited patients, 57 (62%) were found positive for the Mycobacterium tuberculosis complex. The prevalence of rifampicin-resistant tuberculosis (RR-TB) was 9.8% (9/92) and importantly 2.2% were pre-XDR/XDR.

CONCLUSION

This study showed a high rate of rifampicin resistance and the presence of extensively drug-resistant tuberculosis in the study area in new patients. This study highlights the need for further studies of TB drug resistance in the country.

Temporal trend of tuberculosis incidence and its spatial distribution in Macapá - Amapá

OBJECTIVE

To evaluate the temporal trend of tuberculosis incidence after the implementation of the rapid molecular test (RMT-TB), to identify whether tuberculosis presents seasonal variation and to classify the territory according to case density and risk areas in Macapá, Amapá.

METHODS

Ecological study of tuberculosis cases registered in the Sistema de Informação de Agravos de Notificação (SINAN - Information System for Notifiable Diseases) between 2001 and 2017. We used the Prais-Winsten test to classify the temporal trend of incidence and the interrupted time series to identify changes in the temporal trend before and after the implementation of the rapid molecular test, and to verify seasonality in the municipality. The Kernel estimator was used to classify case density and scan statistics to identify areas of tuberculosis risk.

RESULTS

A total of 1,730 cases were identified, with a decreasing temporal trend of tuberculosis incidence (-0.27% per month, 95%CI -0.13 to -0.41). The time series showed no change in level after the implementation of the GeneXpert®MTB/RIF molecular test; however, the incidence increased in the post-test period (+2.09% per month, 95%CI 0.92 to 3.27). Regarding the seasonal variation, it showed growth (+13.7%/month, 95%CI 4.71 to 23.87) from December to June, the rainy season - called amazon winter season -, and decrease (-9.21% per month, CI95% -1.37 to -16.63) in the other periods. We classified areas with high density of cases in the Central and Northern districts using Kernel and identified three protection clusters, SC1 (RR = 0.07), SC2 (RR = 0.23) and SC3 (RR = 0.36), and a high-risk cluster, SC4 (RR = 1.47), with the scan statistics.

CONCLUSION

The temporal trend of tuberculosis incidence was decreasing in the time series; however, detection increased after the introduction of RMT-TB, and tuberculosis showed seasonal behavior. The case distribution was heterogeneous, with a tendency to concentrate in vulnerable and risk territories, evidencing a pattern of disease inequality in the territory.