Miniaturized Rapid Electrochemical Immunosensor Based on Screen Printed Carbon Electrodes for Mycobacterium tuberculosis Detection.

In 2019, over 21% of an estimated 10 million new tuberculosis (TB) patients were either not diagnosed at all or diagnosed without being reported to public health authorities. It is therefore critical to develop newer and more rapid and effective point-of-care diagnostic tools to combat the global TB epidemic. PCR-based diagnostic methods such as Xpert MTB/RIF are quicker than conventional techniques, but their applicability is restricted by the need for specialized laboratory equipment and the substantial cost of scaling-up in low- and middle-income countries where the burden of TB is high. Meanwhile, loop-mediated isothermal amplification (LAMP) amplifies nucleic acids under isothermal conditions with a high efficiency, helps in the early detection and identification of infectious diseases, and can be performed without the need for sophisticated thermocycling equipment. In the present study, the LAMP assay was integrated with screen-printed carbon electrodes and a commercial potentiostat for real time cyclic voltammetry analysis (named as the LAMP-Electrochemical (EC) assay). The LAMP-EC assay was found to be highly specific to TB-causing bacteria and capable of detecting even a single copy of the Mycobacterium tuberculosis (Mtb) IS6110 DNA sequence. Overall, the LAMP-EC test developed and evaluated in the present study shows promise to become a cost-effective tool for rapid and effective diagnosis of TB.

Automated liquid handling robot for rapid lateral flow assay development.

The lateral flow assay (LFA) is one of the most popular technologies on the point-of-care diagnostics market due to its low cost and ease of use, with applications ranging from pregnancy to environmental toxins to infectious disease. While the use of these tests is relatively straightforward, significant development time and effort are required to create tests that are both sensitive and specific. Workflows to guide the LFA development process exist but moving from target selection to an LFA that is ready for field testing can be labor intensive, resource heavy, and time consuming. To reduce the cost and the duration of the LFA development process, we introduce a novel development platform centered on the flexibility, speed, and throughput of an automated robotic liquid handling system. The system comprises LFA-specific hardware and software that enable large optimization experiments with discrete and continuous variables such as antibody pair selection or reagent concentration. Initial validation of the platform was demonstrated during development of a malaria LFA but was readily expanded to encompass development of SARS-CoV-2 and Mycobacterium tuberculosis LFAs. The validity of the platform, where optimization experiments are run directly on LFAs rather than in solution, was based on a direct comparison between the robotic system and a more traditional ELISA-like method. By minimizing hands-on time, maximizing experiment size, and enabling improved reproducibility, the robotic system improved the quality and quantity of LFA assay development efforts.

Incidence and predictors of mortality among persons receiving second-line tuberculosis treatment in sub-Saharan Africa: A meta-analysis of 43 cohort studies.

BACKGROUND: Drug resistance remains from among the most feared public health threats that commonly challenges tuberculosis treatment success. Since 2010, there have been rapid evolution and advances to second-line anti-tuberculosis treatments (SLD). However, evidence on impacts of these advances on incidence of mortality are scarce and conflicting. Estimating the number of people died from any cause during the follow-up period of SLD as the incidence proportion of all-cause mortality is the most informative way of appraising the drug-resistant tuberculosis treatment outcome. We thus aimed to estimate the pooled incidence of mortality and its predictors among persons receiving the SLD in sub-Saharan Africa. METHODS: We systematically identified relevant studies published between January, 2010 and March, 2020, by searching PubMed/MEDLINE, EMBASE, SCOPUS, Cochrane library, Google scholar, and Health Technology Assessment. Eligible English-language publications reported on death and/or its predictors among persons receiving SLD, but those publications that reported death among persons treated for extensively drug-resistant tuberculosis were excluded. Study features, patients' clinical characteristics, and incidence and/or predictors of mortality were extracted and pooled for effect sizes employing a random-effects model. The pooled incidence of mortality was estimated as percentage rate while risks of the individual predictors were appraised based on their independent associations with the mortality outcome. RESULTS: A total of 43 studies were reviewed that revealed 31,525 patients and 4,976 deaths. The pooled incidence of mortality was 17% (95% CI: 15%-18%; I2 = 91.40; P = 0.00). The studies used varied models in identifying predictors of mortality. They found diagnoses of clinical conditions (RR: 2.36; 95% CI: 1.82-3.05); excessive substance use (RR: 2.56; 95% CI: 1.78-3.67); HIV and other comorbidities (RR: 1.96; 95% CI: 1.65-2.32); resistance to SLD (RR: 1.75; 95% CI: 1.37-2.23); and male sex (RR: 1.82; 95% CI: 1.35-2.44) as consistent predictors of the mortality. Few individual studies also reported an increased incidence of mortality among persons initiated with the SLD after a month delay (RR: 1.59; 95% CI: 0.98-2.60) and those persons with history of tuberculosis (RR: 1.21; 95% CI: 1.12-1.32). CONCLUSIONS: We found about one in six persons who received SLD in sub-Saharan Africa had died in the last decade. This incidence of mortality among the drug-resistant tuberculosis patients in the sub-Saharan Africa mirrors the global average. Nevertheless, it was considerably high among the patients who had comorbidities; who were diagnosed with other clinical conditions; who had resistance to SLD; who were males and substance users. Therefore, modified measures involving shorter SLD regimens fortified with newer or repurposed drugs, differentiated care approaches, and support of substance use rehabilitation programs can help improve the treatment outcome of persons with the drug-resistant tuberculosis. TRIAL REGISTRATION NUMBER: CRD42020160473; PROSPERO.

A Rapid Drug Resistance Genotyping Workflow for Mycobacterium tuberculosis, Using Targeted Isothermal Amplification and Nanopore Sequencing.

Phenotypic drug susceptibility testing (DST) for tuberculosis (TB) requires weeks to yield results. Although molecular tests rapidly detect drug resistance-associated mutations (DRMs), they are not scalable to cover the full genome and the many DRMs that can predict resistance. Whole-genome sequencing (WGS) methods are scalable, but if conducted directly on sputum, typically require a target enrichment step, such as nucleic acid amplification. We developed a targeted isothermal amplification-nanopore sequencing workflow for rapid prediction of drug resistance of TB isolates. We used recombinase polymerase amplification (RPA) to perform targeted isothermal amplification (37°C for 90 min) of three regions within the Mycobacterium tuberculosis genome, followed by nanopore sequencing on the MinION. We tested 29 mycobacterial genomic DNA extracts from patients with drug-resistant (DR) TB and compared our results to those of WGS by Illumina and phenotypic DST to evaluate the accuracy of prediction of resistance to rifampin and isoniazid. Amplification by RPA showed fidelity equivalent to that of high-fidelity PCR (100% concordance). Nanopore sequencing generated DRM predictions identical to those of WGS, with considerably faster sequencing run times of minutes rather than days. The sensitivity and specificity of rifampin resistance prediction for our workflow were 96.3% (95% confidence interval [CI], 81.0 to 99.9%) and 100.0% (95% CI, 15.8 to 100.0%), respectively. For isoniazid resistance prediction, the sensitivity and specificity were 100.0% (95% CI, 86.3 to 100.0%) and 100.0% (95% CI, 39.8 to 100.0%), respectively. The workflow consumable costs per sample are less than £100. Our rapid and low-cost drug resistance genotyping workflow provides accurate prediction of rifampin and isoniazid resistance, making it appropriate for use in resource-limited settings. IMPORTANCE Current methods for diagnosing drug-resistant tuberculosis are time consuming, resulting in delays in patients receiving treatment and in transmission onwards. They also require a high level of laboratory infrastructure, which is often only available at centralized facilities, resulting in further delays to diagnosis and additional barriers to deployment in resource-limited settings. This article describes a new workflow that can diagnose drug-resistant TB in a shorter time, with less equipment, and for a lower price than current methods. The amount of TB DNA is first increased without the need for bulky and costly thermocycling equipment. The DNA is then read using a portable sequencer called a MinION, which indicates whether there are tell-tale changes in the DNA that indicate whether the TB strain is drug resistant. Our workflow could play an important role in the future in the fight against the public health challenge that is TB drug resistance.

Costs and cost-effectiveness of Gene Xpert compared to smear microscopy for the diagnosis of pulmonary tuberculosis using real-world data from Arsi zone, Ethiopia.

BACKGROUND: Early diagnosis and treatment are one of the key strategies of tuberculosis control globally, and there are strong efforts in detecting and treating tuberculosis cases in Ethiopia. Smear microscopy examination has been a routine diagnostic test for pulmonary tuberculosis diagnosis in resource-constrained settings for decades. Recently, many countries, including Ethiopia, are scaling up the use of Gene Xpert without the evaluation of the cost and cost-effectiveness implications of this strategy. Therefore, this study evaluated the cost and cost-effectiveness of Gene Xpert (MTB/RIF) and smear microscopy tests to diagnosis tuberculosis patients in Ethiopia. METHODS: We compared the costs and cost-effectiveness of tuberculosis diagnosis using smear microscopy and Gene Xpert among 1332 patients per intervention in the Arsi zone. We applied combinations of top-down and bottom-up costing approaches. The costs were estimated from the health providers' perspective within one year (2017-2018). We employed "cases detected" as an effectiveness measure, and the incremental cost-effectiveness ratio was calculated by dividing the changes in cost and change in effectiveness. All costs and incremental cost-effectiveness ratio were reported in 2018 US$. RESULTS: The unit cost per test for Gene Xpert was $12.9 whereas it is $3.1 for AFB smear microscopy testing. The cost per TB case detected was $77.9 for Gene Xpert while it was $55.8 for the smear microscopy method. The cartridge kit cost accounted for 42% of the overall Gene Xpert's costs and the cost of the reagents and consumables accounted for 41.3% ($1.3) of the unit cost for the smear microscopy method. The ICER for the Gene Xpert strategy was $20.0 per tuberculosis case detected. CONCLUSION: Using Gene Xpert as a routine test instead of standard care (smear microscopy) can be potentially cost-effective. In the cost scenario analysis, the price of the cartridge, the number of tests performed per day, and the life span of the capital equipment were the drivers of the unit cost of the Gene Xpert method. Therefore, Gene Xpert can be a part of the routine TB diagnostic testing strategy in Ethiopia.

EasyNAT MTC assay: A simple, rapid, and low-cost cross-priming amplification method for the detection of mycobacterium tuberculosis suitable for point-of-care testing.

More sensitive, rapid, and affordable diagnostic tools for pulmonary tuberculosis (PTB) are urgently needed. This study aimed to assess the performance of EasyNAT MTC (abbreviation: EasyNAT) (Ustar Biotechnologies, China), a novel isothermal amplification method with a turnaround time of less than two hours that requires a few manual steps to process the sputum. Sputum samples from 249 patients with suspected PTB were subjected to smear, culture, Xpert MTB/RIF (Cepheid, USA) and EasyNAT assay testing. Of the 169 PTB patients, EasyNAT detected more PTB patients than Xpert (72.19% vs. 61.54%, P < 0.05, χ2 = 4.326). Both the Xpert assay and EasyNAT assay detected almost all the culture-positive sputa successfully, but EasyNAT yielded more positive results among the smear-negative and culture-negative PTB cases (44.59% (33/74) vs. 22.97% (17/74), P < 0.01, χ2 = 7.732). Although the specificity of EasyNAT was lower in contrast to Xpert [95.00% (76/80) vs. 98.75% (79/80)], the difference was not significant (P = 0.363, χ2 = 0.826). EasyNAT could be used as an initial test for PTB diagnosis due to its simplicity, rapid turnaround time, high sensitivity, and low cost.

Pathways to diagnosis of pediatric TB patients: A mixed methods study from India.

BACKGROUND: A significant proportion of pediatric tuberculosis (TB) patients go unnotified due to the challenges in diagnosis of TB among children. The experiences of this vulnerable group while going through the TB care cascade remain largely undocumented. The aim of this study was to explore the experiences of pediatric TB patients and families along the pathway to TB diagnosis and appropriate treatment in four cities of India. METHODS: The study used a mixed methods, single phased, embedded design. The primary qualitative and secondary quantitative data were collected simultaneously by interviewing families of 100 randomly selected Xpert MTB/RIF positive pediatric TB patients, under the pediatric TB project, in 4 Indian cities using a semi-structured questionnaire. The qualitative component was analyzed to deduce patterns and themes on the patient and family experiences. Descriptive statistics were used to quantify various events along the TB care pathway including various delays (patient, diagnosis and total) and number of providers visited by patients during the diagnostic process. RESULTS: The median patient, diagnostic and total delays were 3 (IQR: 2,5), 39 (IQR: 23, 91) and 43 days (IQR: 28.5, 98.5), respectively. Patients visited a median of 3 (IQR: 2,4) providers before accessing Xpert MTB/RIF testing. On an average, 68.4% of physicians ordered any test most of them being irrelevant for TB diagnosis. Qualitative data showed considerable suffering for children and their families before and after TB diagnosis including serious concerns of stigma, disruption in education and social life and recurrence of the disease. CONCLUSION: Our study highlights the significant physical and social distress that the children with TB and their families undergo along the TB care pathway. It also shows diagnostic delay in excess of a month during which multiple providers were met and the patients underwent several diagnostic tests, most of them being inappropriate. Efforts to make Xpert MTB/RIF testing more accessible and part of physicians' toolkit will be of considerable value to ease the complexity of TB diagnosis in children. In addition, communication strategy needs to be developed and implemented to generate awareness among general population around pediatric TB and its management.

A study to assess the clinico-radiological presentation and outcome predictors in cases of tubercular meningitis.

INTRODUCTION: Tubercular bacterial meningitis continues to be an important cause of morbidity (especially neurologic handicap) in children from resource-poor countries. The present study was planned to assess the clinical and radiological presentation in cases of tubercular meningitis as well as to study the factors associated with mortality. METHODOLOGY: This study was done over a period of 12 months on children between 5 years and 13 years with suspected TBM. Staging of tubercular meningitis was done according to RNTCP Pediatric TB guideline 2019. RESULT: The study was conducted on a total of 47 pediatric patients with TBM. Mean age of children in present study was 8.77 ± 2.5 years. Our study documented male preponderance for TBM. Severe thinness was observed in 38.3% patients with TBM. Only 59.6% patients were immunized against tuberculosis and history of contact was documented in 40.5% patients. Maximum children belonged to stage I of TBM (59.6%) followed by stage III and stage II in 34% and 6.4% patients respectively. Montoux test positivity was observed in 14.9% patients only. CSF CBNAAT was positive in 6.4% patients. The most common finding was meningeal enhancement seen in 27.7% of patients followed by tuberculomas in 10.6%.Chest X ray was abnormal in 44.7% patients. In present study mortality was observed in 11 (23.4%) cases. Out of various risk factors, mortality was significantly associated with nutritional status and stage of TBM (p < 0.01). CONCLUSION: TBM is associated with high morbidity and mortality in children especially in India where Burden of TB is high. Our study emphasized on the risk factors associated with mortality in children with TBM and need for early diagnosis and appropriate treatment.

Testes comerciais de sondas em linha para detecção do complexo Mycobacterium tuberculosis (MTB), de mutações nas regiões determinantes de resistência a rifampicina e isoniazida (1ª linha) e a fluoroquinolonas e aminoglicosídeos (2ª linha) / Commercial on-line probe tests for detection of Mycobacterium tuberculosis complex (MTB), mutations in rifampicin and isoniazid-resistance-determining regions (1st line) and fluoroquinolones and aminoglycosides (2nd line)

INTRODUÇÃO: Os testes de sonda em linha (LPA) são ensaios qualitativos que utilizam membranas de nitrocelulose com sondas de regiões parciais de genes de resistência. O GenoType MTBDRplus® , a partir de amostras de escarro positivo ou de culturas positivas, identifica o complexo M. tuberculosis e as principais mutações que conferem resistência à rifampicina e isoniazida a partir de sondas das regiões parciais de resistência de determinados genes. O GenoType MTBDRsl® possibilita a identificação de resistência também aos medicamentos injetáveis e de segunda linha, por meio de sondas de genes de resistência conhecidos. A população alvo desse abarca indivíduos com comorbidades ou não, de ambos os sexos, todas as idades, provenientes de qualquer país independentemente da incidência e prevalência regionais da doença, com suspeita de tuberculose pulmonar ou extrapulmonar ou indivíduos diagnosticados com tuberculose, independentemente da baciloscopia, tratados previamente ou não, e suspeita de resistência a drogas de primeira ou segunda linha utilizadas no tratamento das formas resistentes da doença. EQUIPAMENTO: Testes comerciais de sondas em linha para detecção do complexo Mycobacterium tuberculosis (MTB), de mutações nas regiões determinan

Distribution of molecular strains of Mycobacterium tuberculosis in an intermediate burden Asia Pacific city.

Hong Kong is an intermediate tuberculosis (TB) burden city in Asia Pacific with slow decline of case notification in the last decade. By 24-loci mycobacterial interspersed repetitive units - variable number of tandem repeats genotyping, we examined 534 Mycobacterium tuberculosis isolates collected from culture-positive hospitalised TB patients in a 1.7 million population geographic region in the city. Overall, 286 (75%) were classified as Beijing genotype, of which 216 (76%) and 59 (21%) belonged to modern and ancient sub-lineage, respectively. Only two cases were genetically clustered while spatial clustering was absent. Male gender, permanent residency in Hong Kong and born in Hong Kong or Mainland China were associated with Beijing genotype. The high prevalence of Beijing modern lineage was similar to that in East Asia, which reflected the pattern resulting from population migration. The paucity of clustering suggested that reactivation accounted for most of the TB disease cases, which was and echoed by observation that half were 60 years old or above, and the presence of co-morbid medical conditions. The predominance of reactivation TB cases in intermediate burden localities implies that the detection and control of latent TB infection would be the major challenge in achieving TB elimination.

Strengthening health systems to improve the value of tuberculosis diagnostics in South Africa: A cost and cost-effectiveness analysis.

BACKGROUND: In South Africa, replacing smear microscopy with Xpert-MTB/RIF (Xpert) for tuberculosis diagnosis did not reduce mortality and was cost-neutral. The unchanged mortality has been attributed to suboptimal Xpert implementation. We developed a mathematical model to explore how complementary investments may improve cost-effectiveness of the tuberculosis diagnostic algorithm. METHODS: Complementary investments in the tuberculosis diagnostic pathway were compared to the status quo. Investment scenarios following an initial Xpert test included actions to reduce pre-treatment loss-to-follow-up; supporting same-day clinical diagnosis of tuberculosis after a negative result; and improving access to further tuberculosis diagnostic tests following a negative result. We estimated costs, deaths and disability-adjusted-life-years (DALYs) averted from provider and societal perspectives. Sensitivity analyses explored the mediating influence of behavioural, disease- and organisational characteristics on investment effectiveness. FINDINGS: Among a cohort of symptomatic patients tested for tuberculosis, with an estimated active tuberculosis prevalence of 13%, reducing pre-treatment loss-to-follow-up from ~20% to ~0% led to a 4% (uncertainty interval [UI] 3; 4%) reduction in mortality compared to the Xpert scenario. Improving access to further tuberculosis diagnostic tests from ~4% to 90% among those with an initial negative Xpert result reduced overall mortality by 28% (UI 27; 28) at $39.70/ DALY averted. Effectiveness of investment scenarios to improve access to further diagnostic tests was dependent on a high return rate for follow-up visits. INTERPRETATION: Investing in direct and indirect costs to support the TB diagnostic pathway is potentially highly cost-effective.

Performance Assessment of Xpert MTB/RIF Assay for Detecting Pulmonary Tuberculosis and Rifampin Resistance in a Tertiary Care Hospital in Korea.

In this study, we aimed to assess the performance of the Xpert MTB/RIF assay for the detection of pulmonary tuberculosis compared to the acid-fast bacilli (AFB) smear and culture analysis, and the incidence of rifampin resistance using the drug susceptibility test. The specimens referred for AFB smear and culture analysis and Xpert MTB/RIF assay from April 2015 to March 2018 were retrospectively reviewed. The sensitivity, specificity, and mean cycle threshold (Ct) values obtained in Xpert MTB/RIF assay and for rifampin resistance were analyzed. The results of Xpert MTB/RIF assay for pulmonary tuberculosis were evaluated based on the AFB smear grade. Among 3,840 specimens, 491 were positive in Xpert MTB/RIF assay and 626 in culture analysis. The sensitivity and specificity of Xpert MTB/RIF assay were 75.6% and 99.4%, respectively. The sensitivity of Xpert MTB/RIF assay for smear-positive/culture-positive specimens was 98.6% and that of smear-negative and -trace/culture-positive specimens was 63.1%. The positivity of Xpert MTB/RIF assay for culture-positive specimens was 89.9%, 98.6%, 95.7%, 100.0%, and 100.0% for the smear grades trace, 1+, 2+, 3+, 4+, respectively. The Ct values of 491 specimens significantly decreased as the AFB smear grade increased (P < 0.0001). The Ct values of smear-positive, -trace, and -negative specimens were 21.7 ± 4.2, 26.5 ± 3.9, and 27.4 ± 3.6, respectively. Rifampin resistance evaluated using Xpert MTB/RIF assay and culture analysis exhibited a correlation of 98.3%. The region covered by probe E was the most frequently mutated region (50.0%). Xpert MTB/RIF assay demonstrated reliable performance in detecting pulmonary tuberculosis from smear-positive and culture-positive specimens; however, further improvements are still required to detect smear-negative and culture-positive specimens.

Development of a two-step nucleic acid amplification test for accurate diagnosis of the Mycobacterium tuberculosis complex.

The Mycobacterium tuberculosis complex (MTBC) remains one of the top 10 leading causes of death globally. The early diagnosis of MTBC can reduce mortality and mitigate disease transmission. However, current nucleic acid amplification diagnostic test methods are generally time-consuming and show suboptimal diagnostic performance, especially in extrapulmonary MTBC samples or acid-fast stain (AFS)-negative cases. Thus, development of an accurate assay for the diagnosis of MTBC is necessary, particularly under the above mentioned conditions. In this study, a single-tube nested real-time PCR assay (N-RTP) was developed and compared with a newly in-house-developed high-sensitivity real-time PCR assay (HS-RTP) using 134 clinical specimens (including 73 pulmonary and 61 extrapulmonary specimens). The amplification efficiency of HS-RTP and N-RTP was 99.8% and 100.7%, respectively. The sensitivity and specificity of HS-RTP and N-RTP for the diagnosis of MTBC in these specimens were 97.5% (77/79) versus 94.9% (75/79) and 80.0% (44/55) versus 89.1% (49/55), respectively. The sensitivity and specificity of HS-RTP and N-RTP for the diagnosis of MTBC in pulmonary specimens were 96.3% (52/54) versus 96.3% (52/54) and 73.7.0% (14/19) versus 89.5% (17/19), respectively; in extrapulmonary specimens, the sensitivity and specificity of HS-RTP and N-RTP were 100% (25/25) versus 92% (23/25) and 83.3% (30/36) versus 88.9% (32/36), respectively. Among the AFS-negative cases, the sensitivity and specificity of HS-RTP and N-RTP were 97.0% (32/33) versus 90.9% (30/33) and 88.0% (44/50) versus 92.0% (46/50), respectively. Overall, the sensitivity of HS-RTP was higher than that of N-RTP, and the performance was not compromised in extrapulmonary specimens and under AFS-negative conditions. In contrast, the specificity of the N-RTP assay was higher than that of the HS-RTP assay in all types of specimens. In conclusion, the HS-RTP assay would be useful for screening patients suspected of exhibiting an MTBC infection due to its higher sensitivity, while the N-RTP assay could be used for confirmation because of its higher specificity. Our results provide a two-step method (screen to confirm) that simultaneously achieves high sensitivity and specificity in the diagnosis of MTBC.

Systematic Review of Pooling Sputum as an Efficient Method for Xpert MTB/RIF Tuberculosis Testing during the COVID-19 Pandemic.

GeneXpert-based testing with Xpert MTB/RIF or Ultra assays is essential for tuberculosis diagnosis. However, testing may be affected by cartridge and staff shortages. More efficient testing strategies could help, especially during the coronavirus disease pandemic. We searched the literature to systematically review whether GeneXpert-based testing of pooled sputum samples achieves sensitivity and specificity similar to testing individual samples; this method could potentially save time and preserve the limited supply of cartridges. From 6 publications, we found 2-sample pools using Xpert MTB/RIF had 87.5% and 96.0% sensitivity (average sensitivity 94%; 95% CI 89.0%-98.0%) (2 studies). Four-sample pools averaged 91% sensitivity with Xpert MTB/RIF (2 studies) and 98% with Ultra (2 studies); combining >4 samples resulted in lower sensitivity. Two studies reported that pooling achieved 99%-100% specificity and 27%-31% in cartridge savings. Our results show that pooling may improve efficiency of GeneXpert-based testing.

Modelling the global burden of drug-resistant tuberculosis avertable by a post-exposure vaccine.

There have been notable advances in the development of vaccines against active tuberculosis (TB) disease for adults and adolescents. Using mathematical models, we seek to estimate the potential impact of a post-exposure TB vaccine, having 50% efficacy in reducing active disease, on global rifampicin-resistant (RR-) TB burden. In 30 countries that together accounted for 90% of global RR-TB incidence in 2018, a future TB vaccine could avert 10% (95% credible interval: 9.7-11%) of RR-TB cases and 7.3% (6.6-8.1%) of deaths over 2020-2035, with India, China, Indonesia, Pakistan, and the Russian Federation having the greatest contribution. This impact would increase to 14% (12-16%) and 31% (29-33%) respectively, when combined with improvements in RR-TB diagnosis and treatment relative to a scenario of no vaccine and no such improvements. A future TB vaccine could have important implications for the global control of RR-TB, especially if implemented alongside enhancements in management of drug resistance.

Capacity building for whole genome sequencing of Mycobacterium tuberculosis and bioinformatics in high TB burden countries.

BACKGROUND: Whole genome sequencing (WGS) is increasingly used for Mycobacterium tuberculosis (Mtb) research. Countries with the highest tuberculosis (TB) burden face important challenges to integrate WGS into surveillance and research. METHODS: We assessed the global status of Mtb WGS and developed a 3-week training course coupled with long-term mentoring and WGS infrastructure building. Training focused on genome sequencing, bioinformatics and development of a locally relevant WGS research project. The aim of the long-term mentoring was to support trainees in project implementation and funding acquisition. The focus of WGS infrastructure building was on the DNA extraction process and bioinformatics. FINDINGS: Compared to their TB burden, Asia and Africa are grossly underrepresented in Mtb WGS research. Challenges faced resulted in adaptations to the training, mentoring and infrastructure building. Out-of-date laptop hardware and operating systems were overcome by using online tools and a Galaxy WGS analysis pipeline. A case studies approach created a safe atmosphere for students to formulate and defend opinions. Because quality DNA extraction is paramount for WGS, a biosafety level 3 and general laboratory skill training session were added, use of commercial DNA extraction kits was introduced and a 2-week training in a highly equipped laboratory was combined with a 1-week training in the local setting. INTERPRETATION: By developing and sharing the components of and experiences with a sequencing and bioinformatics training program, we hope to stimulate capacity building programs for Mtb WGS and empower high-burden countries to play an important role in WGS-based TB surveillance and research.

Addressing the drug-resistant tuberculosis challenge through implementing a mixed model of care in Uganda.

Worldwide, Drug-resistant Tuberculosis (DR-TB) remains a big problem; the diagnostic capacity has superseded the clinical management capacity thereby causing ethical challenges. In Sub-Saharan Africa, treatment is either inadequate or lacking and some diagnosed patients are on treatment waiting lists. In Uganda, various health system challenges impeded scale-up of DR-TB care in 2012; only three treatment initiation facilities existed, with only 41 of the estimated 1010 RR-TB/MDR-TB cases enrolled on treatment yet 300 were on the waiting list and there was no DR-TB treatment scale-up plan. To scale up care, the National TB and leprosy Program (NTLP) with partners rolled out a DR-TB mixed model of care. In this paper, we share achievements and outcomes resulting from the implementation of this mixed Model of DR-TB care. Routine NTLP DR-TB program data on treatment initiation site, number of patients enrolled, their demographic characteristics, patient category, disease classification (based on disease site and human immunodeficiency virus (HIV) status), on co-trimoxazole preventive therapy (CPT) and antiretroviral therapy (ART) statuses, culture results, smear results and treatment outcomes (6, 12, and 24 months) from 2012 to 2017 RR-TB/MDR-TB cohorts were collected from all the 15 DR-TB treatment initiation sites and descriptive analysis was done using STATA version 14.2. We presented outcomes as the number of patient backlog cleared, DR-TB initiation sites, RR-TB/DR-TB cumulative patients enrolled, percentage of co-infected patients on the six, twelve interim and 24 months treatment outcomes as per the Uganda NTLP 2016 Programmatic Management of drug-resistant Tuberculosis (PMDT) guidelines (NTLP, 2016). Over the period 2013-2015, the RR-TB/MDR-TB Treatment success rate (TSR) was sustained between 70.1% and 74.1%, a performance that is well above the global TSR average rate of 50%. Additionally, the cure rate increased from 48.8% to 66.8% (P = 0.03). The Uganda DR-TB mixed model of care coupled with early application of continuous improvement approaches, enhanced cohort reviews and use of multi-disciplinary teams allowed for rapid DR-TB program expansion, rapid clearance of patient backlog, attainment of high cumulative enrollment and high treatment success rates. Sustainability of these achievements is needed to further reduce the DR-TB burden in the country. We highly recommend this mixed model of care in settings with similar challenges.

Demonstration of a fast and easy sample-to-answer protocol for tuberculosis screening in point-of-care settings: A proof of concept study.

We sought to develop a smooth and low cost sample preparation and DNA extraction protocol, streamlined with a ready-to-use qPCR in a portable instrument to overcome some of the existing hurdles. Several solutions were evaluated as to their ability to liquefy a mucin-based matrix. Each liquefied matrix, supplemented with either Mycobacterium tuberculosis (MTB) H37Rv strain DNA or intact cells, was aliquoted onto a filter paper embedded with solubilizing agents, and was subsequently dried up. Most of the nucleic acids, including genomic DNA from the bacilli and the host, binds to the filter paper. Next, several protocols were evaluated to elute the DNA from the paper, using qPCR to detect the insertion sequence IS6110, a M. tuberculosis complex genomic marker. The limit of detection (LOD) of the best protocol was then evaluated using parallel seeding and colony counting. The protocol was also evaluated using seventeen sputum samples, previously characterized by the GeneXpert or culture. Two instruments (the ABI7500 Standard and the Q3-Plus system) and two reagents storage formats (frozen or ready-to-use) were evaluated. Solutions containing guanidine isothiocyanate exerted the best liquefying effect on the mucin-based matrix extracted from one 6-mm punches, followed by a brief incubation at 95°C. The resulting DNA contained impurities, but a simple 1:10 dilution elicited the detection of MTB and human genomic targets. The described protocol presented an apparent LOD of 02 CFU/mL of MTB. Challenging the protocol with previously characterized samples showed substantial agreement with GeneXpert MTB/RIF results (sensitivity of 90%, agreement of 88.9%, kappa coefficient of 0.77), and moderate agreement with culture results (sensitivity of 100%, agreement of 78.9%, kappa coefficient of 0.58). This work presents a sensitive proof-of-concept protocol for sputum liquefaction and decontamination followed by a simple DNA extraction procedure, in which the extraction steps are streamlined with a ready-to-use qPCR in a portable instrument that can be employed in low infrastructure settings.

Coverage and fidelity of the Xpert MTB/RIF™ implementation in a high-burden area for pulmonary tuberculosis in Colombia / [Cobertura y fidelidad de la prueba Xpert MTB/RIF™ en un área de alta carga de tuberculosis pulmonar en Colombia].

Introduction: The Xpert MTB/RIF™ is a rapid molecular test that diagnoses tuberculosis and rifampin resistance. Since 2010, it is recommended by the World Health Organization (WHO) and although it was introduced in Colombia since 2012, the results of its implementation are unknown. Objective: To describe the coverage and fidelity in the implementation of the Xpert MTB/RIF™ in patients with pulmonary tuberculosis in a city with a high burden for the disease in Colombia. Materials and methods: We conducted a retrospective, descriptive study of cases from a tuberculosis program in Cali between 2013 and 2019. We estimated the coverage as the total number of tests used compared to the cases registered in the program and the fidelity based on international Xpert MTB/RIF™ implementation protocols. We performed a multivariate analysis of multiple correspondences between the test and the sociodemographic variables. Results: We included 6,328 patients with pulmonary tuberculosis of whom 181 were drugresistant. The Xpert MTB/RIF™ coverage was 10,3% (n=655) with an annual variation between 0.2% and 23%. Loyalty among the highest risk groups of MDR-TB was 46.8%. The use of the test was related to being an Afro-Colombian man between 41 and 60 years of age. Conclusions: The coverage of the Xpert MTB/RIF in Cali is low and its use does not follow the recommended prioritization for its implementation. Implementation strategies are required for its proper use to contribute to the goal of ending tuberculosis.

Introducción. La prueba Xpert MTB/RIF™ es una prueba molecular rápida para el diagnóstico de la tuberculosis y la resistencia a la rifampicina. Desde el 2010 es la recomendada por la Organización Mundial de la Salud (OMS) y, aunque fue introducida en Colombia en el 2012, se desconocen los resultados de su uso. Objetivo. Describir la cobertura y la fidelidad en el uso de la prueba Xpert MTB/RIF™ en pacientes con tuberculosis pulmonar en una ciudad con alta carga de la enfermedad en Colombia. Materiales y métodos. Se hizo un estudio retrospectivo descriptivo de casos del programa de tuberculosis en Cali entre el 2013 y el 2019. La cobertura se estimó como el total de pruebas empleadas en los casos registrados en el programa. La fidelidad se midió con base en los protocolos internacionales de uso de la Xpert MTB/RIF™. Además, se hizo un análisis de correspondencias múltiples entre la prueba y las variables sociodemográficas. Resultados. Se incluyeron 6.328 pacientes con tuberculosis pulmonar, de los cuales 181 eran resistentes a los fármacos. La cobertura total de la Xpert MTB/RIF™ durante el periodo de estudio fue de 10,3 % (n=655), con una variación anual entre 0,2 y 23 %. La fidelidad fue de 46,8 % para los grupos de mayor riesgo de tuberculosis multirresistente (TB-MDR). El uso de la prueba se relacionó con la condición de ser hombre, afrocolombiano, y tener entre 41 y 60 años de edad. Conclusiones. La cobertura de la prueba Xpert MTB/RIF™ en Cali es baja y su uso no responde a la priorización recomendada para su implementación. Se requieren estrategias para promover su uso adecuado, de manera que contribuya a la meta de poner fin a la tuberculosis.