BACKGROUND: Multidrug-resistant (MDR) Mycobacterium tuberculosis complex strains not detected by commercial molecular drug susceptibility testing (mDST) assays due to the RpoB I491F resistance mutation are threatening the control of MDR tuberculosis (MDR-TB) in Eswatini. METHODS: We investigate the evolution and spread of MDR strains in Eswatini with a focus on bedaquiline (BDQ) and clofazimine (CFZ) resistance using whole-genome sequencing in two collections ((1) national drug resistance survey, 2009–2010; (2) MDR strains from the Nhlangano region, 2014–2017). RESULTS: MDR strains in collection 1 had a high cluster rate (95%, 117/123 MDR strains) with 55% grouped into the two largest clusters (gCL3, n = 28; gCL10, n = 40). All gCL10 isolates, which likely emerged around 1993 (95% highest posterior density 1987–1998), carried the mutation RpoB I491F that is missed by commercial mDST assays. In addition, 21 (53%) gCL10 isolates shared a Rv0678 M146T mutation that correlated with elevated minimum inhibitory concentrations (MICs) to BDQ and CFZ compared to wild type isolates. gCL10 isolates with the Rv0678 M146T mutation were also detected in collection 2. CONCLUSION: The high clustering rate suggests that transmission has been driving the MDR-TB epidemic in Eswatini for three decades. The presence of MDR strains in Eswatini that are not detected by commercial mDST assays and have elevated MICs to BDQ and CFZ potentially jeopardizes the successful implementation of new MDR-TB treatment guidelines. Measures to limit the spread of these outbreak isolates need to be implemented urgently. ; The European Union TB-PAN-NET (FP7-223681) project, by Médecins Sans Frontières-Switzerland, and by German Center for Infection Research, Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germanys Excellence Strategy – EXC 2167, and Leibniz Science Campus Evolutionary Medicine of the LUNG (EvoLUNG). ; http://genomemedicine.com ; pm2021 ; Medical Microbiology
10 Pages, 1 Figure, 3 Tables. Supplementary information: http://dx.doi.org/10.1038/s41598-018-33731-1 ; Drug-resistant tuberculosis poses a persistent public health threat. The ReSeqTB platform is a collaborative, curated knowledgebase, designed to standardize and aggregate global Mycobacterium tuberculosis complex (MTBC) variant data from whole genome sequencing (WGS) with phenotypic drug susceptibility testing (DST) and clinical data. We developed a unified analysis variant pipeline (UVP) ( https://github.com/CPTR-ReSeqTB/UVP ) to identify variants and assign lineage from MTBC sequence data. Stringent thresholds and quality control measures were incorporated in this open source tool. The pipeline was validated using a well-characterized dataset of 90 diverse MTBC isolates with conventional DST and DNA Sanger sequencing data. The UVP exhibited 98.9% agreement with the variants identified using Sanger sequencing and was 100% concordant with conventional methods of assigning lineage. We analyzed 4636 publicly available MTBC isolates in the ReSeqTB platform representing all seven major MTBC lineages. The variants detected have an above 94% accuracy of predicting drug based on the accompanying DST results in the platform. The aggregation of variants over time in the platform will establish confidence-graded mutations statistically associated with phenotypic drug resistance. These tools serve as critical reference standards for future molecular diagnostic assay developers, researchers, public health agencies and clinicians working towards the control of drug-resistant tuberculosis. ; This study was supported by the Bill & Melinda Gates Foundation under grant agreement OPP1115887 to C-Path for developing the ReSeqTB drug resistance data sharing platform and under grant agreement FIND OPP1115209 to address how to score mutations in the ReSeqTB data sharing platform initiative. The South African MRC and the EDCTP support K. Dheda. I. Comas is supported by the Ministerio de Economía y Competitividad (Spanish Government) research grant SAF2016-77346-R and the European Research Council (ERC) (638553-TB-ACCELERATE). L. Chindelevitch acknowledges support by NSERC, Genome Canada, and the Sloan Foundation. Use of trade names is for identification only and does not constitute endorsement by the US Department of Health and Human Services, the US Public Health Service, or the Centers for Disease Control and Prevention. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the funding agency. ; Peer reviewed
A screening of more than 1,500 drug-resistant strains of Mycobacterium tuberculosis revealed evolutionary patterns characteristic of positive selection for three alanine racemase (Alr) mutations. We investigated these mutations using molecular modeling, in vitro MIC testing, as well as direct measurements of enzymatic activity, which demonstrated that these mutations likely confer resistance to D-cycloserine. ; Funding Agencies|University of Otago; Health Research Council; Maurice Wilkins Centre; European Union [FP7-278864-2]; German Center for Infection Research (DZIF); Fundacao para a Ciencia e a Tecnologia, Portugal [UID/Multi/04413/2013, SFRH/BPD/100688/2014, SFRH/BPD/95406/2013]; Wellcome Trust [201344/Z/16/Z]; Medical Research Council UK [MR/K000551/1, MR/M01360X/1, MR/N010469/1]; Indian Council of Medical Research, New Delhi; L2 Diagnostics LLC, New Haven; Pacific Biosciences, Inc.; Illumina, Inc.; European Society of Mycobacteriology; Hain Lifescience; UK Department of Health [HICF-T5-342, WT098600]; Wellcome Trust
13 Pages, 1 Figure, 4 tables. The authors' affiliations are listed in the Supplementary Appendix, available at NEJM.org. Supplementary Material, available at http://dx.doi.org/10.1056/NEJMoa1800474 ; BACKGROUND: The World Health Organization recommends drug-susceptibility testing of Mycobacterium tuberculosis complex for all patients with tuberculosis to guide treatment decisions and improve outcomes. Whether DNA sequencing can be used to accurately predict profiles of susceptibility to first-line antituberculosis drugs has not been clear. METHODS: We obtained whole-genome sequences and associated phenotypes of resistance or susceptibility to the first-line antituberculosis drugs isoniazid, rifampin, ethambutol, and pyrazinamide for isolates from 16 countries across six continents. For each isolate, mutations associated with drug resistance and drug susceptibility were identified across nine genes, and individual phenotypes were predicted unless mutations of unknown association were also present. To identify how whole-genome sequencing might direct first-line drug therapy, complete susceptibility profiles were predicted. These profiles were predicted to be susceptible to all four drugs (i.e., pansusceptible) if they were predicted to be susceptible to isoniazid and to the other drugs or if they contained mutations of unknown association in genes that affect susceptibility to the other drugs. We simulated the way in which the negative predictive value changed with the prevalence of drug resistance. RESULTS: A total of 10,209 isolates were analyzed. The largest proportion of phenotypes was predicted for rifampin (9660 [95.4%] of 10,130) and the smallest was predicted for ethambutol (8794 [89.8%] of 9794). Resistance to isoniazid, rifampin, ethambutol, and pyrazinamide was correctly predicted with 97.1%, 97.5%, 94.6%, and 91.3% sensitivity, respectively, and susceptibility to these drugs was correctly predicted with 99.0%, 98.8%, 93.6%, and 96.8% specificity. Of the 7516 isolates with complete phenotypic drug-susceptibility profiles, 5865 (78.0%) had complete genotypic predictions, among which 5250 profiles (89.5%) were correctly predicted. Among the 4037 phenotypic profiles that were predicted to be pansusceptible, 3952 (97.9%) were correctly predicted. CONCLUSIONS: Genotypic predictions of the susceptibility of M. tuberculosis to first-line drugs were found to be correlated with phenotypic susceptibility to these drugs. (Funded by the Bill and Melinda Gates Foundation and others.). ; Supported by grants from the Bill and Melinda Gates Foundation (OPP1133541, to CRyPTIC, plus separate support to Dr. Rodwell), a Wellcome Trust/Newton Fund–MRC Collaborative Award (200205/Z/15/Z, to CRyPTIC), the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre (BRC) and NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance at University of Oxford in partnership with Public Health England, the NIHR Biomedical Research Centre at Barts, the NIHR Biomedical Research Centre at Imperial, the NIHR and NHS England (to the 100,000 Genomes Project, which is managed by Genomics England, a wholly owned company of the U.K. Department of Health), the Wellcome Trust, the Medical Research Council, Public Health England, a grant from the National Science and Technology Key Program of China (2014ZX10003002), a grant from the National Basic Research program of China (2014CB744403), a grant from the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB29020000), a grant from the European Commission Seventh Framework Program (FP7/2007-2013, to Borstel under grant agreement 278864 in the framework of the Patho-NGen-Trace project), the German Center for Infection Research (to Borstel), Leibniz Science Campus Evolutionary Medicine of the Lung (EvoLUNG), the Belgian Ministry of Social Affairs (to the Belgian Reference Center for Tuberculosis and Mycobacteria from Bacterial Diseases Service through a fund within the Health Insurance System), the French governmental program "Investing for the Future" (to Genoscreen), a grant from the European Commission Seventh Framework Program (FP7/2007-2013, to Genoscreen under grant agreement 278864 in the framework of the Patho-NGen-Trace project), grants from the Drug Resistant Tuberculosis Fund (R015833003, to Dr. Chaiprasert), the Faculty of Medicine, Siriraj Hospital, Mahidol University (to Dr. Chaiprasert), a grant from the Ministry of Economy and Competitiveness (MINECO), Spain (SAF2016-77346-R, to Dr. Comas), a grant from the European Research Council (638553-TB-ACCELERATE, to Dr. Comas), a grant from the BC Centre for Disease Control Foundation for Population and Public Health (to Dr. Gardy), a grant from the British Colombia Lung Association (to Dr. Gardy), grants from the Wellcome Trust and the Royal Society (101237/Z/13/Z and 102541/A/13/Z, to Drs. Wilson and Iqbal [Sir Henry Dale Fellows]), a grant from the National University of Singapore Yong Loo Lin School of Medicine Aspiration Fund (NUHSRO/2014/069/AF-New Idea/04, to Drs. Ong and Teo), a European Commission Seventh Framework Program European Genetic Network (EUROGEN) grant (201483, to Dr. Drobniewski), and the National Institute of Allergy and Infectious Diseases, National Institutes of Health (to Dr. Rodwell). Dr. T. Walker is an NIHR Academic Clinical Lecturer, and Drs. Crook, Peto, and Caulfield are NIHR Senior Investigators. No potential conflict of interest relevant to this article was reported. Disclosure forms provided by the authors are available with the full text of this article at NEJM.org. We thank Stéphanie Duthoy, Carina Hahn, Alamdar Hussain, Yannick Laurent, Mathilde Mairey, Vanessa Mohr, and Mahmood Qadir for technical assistance and George F. Gao, Director of the Chinese Center for Disease Control and Prevention, for directing the Chinese grant and sequencing program ; Peer reviewed