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1. Bedaquiline and clofazimine resistance in Mycobacterium tuberculosis: an in-vitro and in-silico data analysis

Author

Sonnenkalb, L, Carter, JJ, Spitaleri, A, Iqbal, Z, Hunt, M, Malone, KM, Utpatel, C, Cirillo, DM, Rodrigues, C, Nilgiriwala, KS, Fowler, PW, Merker, M, Niemann, S, Barilar, I, Battaglia, S, Borroni, E, Brandao, AP, Brankin, A, Cabibbe, AM, Carter, J, Claxton, P, Clifton, DA, Cohen, T, Coronel, J, Crook, DW, Dreyer, V, Earle, SG, Escuyer, V, Ferrazoli, L, Fu Gao, G, Gardy, J, Gharbia, S, Ghisi, KT, Ghodousi, A, Gibertoni Cruz, AL, Grandjean, L, Grazian, C, Groenheit, R, Guthrie, JL, He, W, Hoffmann, H, Hoosdally, SJ, Ismail, NA, Jarrett, L, Joseph, L, Jou, R, Kambli, P, Khot, R, Knaggs, J, Koch, A, Kohlerschmidt, D, Kouchaki, S, Lachapelle, AS, Lalvani, A, Grandjean Lapierre, S, Laurenson, IF, Letcher, B, Lin, W-H, Liu, C, Liu, D, Mandal, A, Mansjö, M, Matias, D, Meintjes, G, De Freitas Mendes, F, Mihalic, M, Millard, J, Miotto, P, Mistry, N, Moore, D, Musser, KA, Ngcamu, D, Hoang, NN, Nimmo, C, Okozi, N, Oliveira, RS, Omar, SV, Paton, N, Peto, TEA, Watanabe Pinhata, JM, Plesnik, S, Puyen, ZM, Rabodoarivelo, MS, Rakotosamimanana, N, Rancoita, PMV, Rathod, P, Rodger, G, Rodwell, TC, Roohi, E, Santos-Lazaro, D, Shah, S, Kohl, TA, Smith, G, Solano, W, Supply, P, Surve, U, Tahseen, S, Thuong, NTT, Thwaites, G, Todt, K, Trovato, A, Van Rie, A, Vijay, S, Walker, TM, Walker, SA, Warren, R, Werngren, J, Wijkander, M, Wilkinson, RJ, Wilson, DJ, Wintringer, P, Yu, XX, Yang, Y, Zhao, Y, Yao, S-Y, Zhu, B, and Consortium, Comprehensive Resistance Prediction for Tuberculosis: an International

Subjects
Microbiology (medical), Infectious Diseases, Virology, Microbiology
Abstract

Background Bedaquiline is a core drug for the treatment of multidrug-resistant tuberculosis; however, the understanding of resistance mechanisms is poor, which is hampering rapid molecular diagnostics. Some bedaquiline-resistant mutants are also cross-resistant to clofazimine. To decipher bedaquiline and clofazimine resistance determinants, we combined experimental evolution, protein modelling, genome sequencing, and phenotypic data. Methods For this in-vitro and in-silico data analysis, we used a novel in-vitro evolutionary model using subinhibitory drug concentrations to select bedaquiline-resistant and clofazimine-resistant mutants. We determined bedaquiline and clofazimine minimum inhibitory concentrations and did Illumina and PacBio sequencing to characterise selected mutants and establish a mutation catalogue. This catalogue also includes phenotypic and genotypic data of a global collection of more than 14 000 clinical Mycobacterium tuberculosis complex isolates, and publicly available data. We investigated variants implicated in bedaquiline resistance by protein modelling and dynamic simulations. Findings We discerned 265 genomic variants implicated in bedaquiline resistance, with 250 (94%) variants affecting the transcriptional repressor (Rv0678) of the MmpS5–MmpL5 efflux system. We identified 40 new variants in vitro, and a new bedaquiline resistance mechanism caused by a large-scale genomic rearrangement. Additionally, we identified in vitro 15 (7%) of 208 mutations found in clinical bedaquiline-resistant isolates. From our in-vitro work, we detected 14 (16%) of 88 mutations so far identified as being associated with clofazimine resistance and also seen in clinically resistant strains, and catalogued 35 new mutations. Structural modelling of Rv0678 showed four major mechanisms of bedaquiline resistance: impaired DNA binding, reduction in protein stability, disruption of protein dimerisation, and alteration in affinity for its fatty acid ligand. Interpretation Our findings advance the understanding of drug resistance mechanisms in M tuberculosis complex strains. We have established an extended mutation catalogue, comprising variants implicated in resistance and susceptibility to bedaquiline and clofazimine. Our data emphasise that genotypic testing can delineate clinical isolates with borderline phenotypes, which is essential for the design of effective treatments. Funding Leibniz ScienceCampus Evolutionary Medicine of the Lung, Deutsche Forschungsgemeinschaft, Research Training Group 2501 TransEvo, Rhodes Trust, Stanford University Medical Scientist Training Program, National Institute for Health and Care Research Oxford Biomedical Research Centre, Oxford University Hospitals NHS Foundation Trust, Bill & Melinda Gates Foundation, Wellcome Trust, and Marie Skłodowska-Curie Actions.

Published
2023
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2. A crowd of BashTheBug volunteers reproducibly and accurately measure the minimum inhibitory concentrations of 13 antitubercular drugs from photographs of 96-well broth microdilution plates

Author

Fowler, P.W., Wright, C., Spiers, H., Zhu, T., Baeten, E.M.L., Hoosdally, S.W., Cruz, A.L.G., Roohi, A., Kouchaki, S., Walker, T.M., Peto, T.E.A., Miller, G., Lintott, C., Clifton, D., Crook, D.W., Walker, A.S., Barilar, I., Battaglia, S., Borroni, E., Brandao, A.P., Brankin, A., Cabibbe, A.M., Carter, J., Chetty, D., Cirillo, D.M., Claxton, P., Clifton, D.A., Cohen, T., Coronel, Jorge, Dreyer, V., Earle, S.G., Escuyer, V., Ferrazoli, L., Gao, G.F., Gardy, J., Gharbia, S., Ghisi, K.T., Ghodousi, A., Grandjean, Louis, Grazian, C., Groenheit, R., Guthrie, J.L., He, W., Hoffmann, H., Hoosdally, S.J., Martinhunt, M., Iqbal, Z., Ismail, N.A., Jarrett, L., Joseph, L., Jou, R., Kambli, P., Khot, R., Knaggs, J., Koch, A., Kohlerschmidt, D., Lachapelle, A.S., Lalvani, A., Lapierre, S.G., Laurenson, I.F., Letcher, B., Lin, W.-H., Liu, C., Liu, D., Malone, K.M., Mandal, A., Mansjõ, M., Matias, D., Meintjes, G., Mendes, F.D.F., Merker, M., Mihalic, M., Millard, J., Miotto, P., Mistry, N., Moore, David Alexander James, Musser, K.A., Ngcamu, D., Nhung, H.N., Niemann, S., Nilgiriwala, K.S., Nimmo, C., O’Donnell, M., Okozi, N., Oliveira, R.S., Omar, S.V., Paton, N., Pinhata, J.M.W., Plesnik, S., Puyen, Z.M., Rabodoarivelo, M.S., Rakotosamimanana, N., Rancoita, P.M.V., Rathod, P., Robinson, E., Rodger, G., Rodrigues, C., Rodwell, T.C., Santos-Lazaro, D., Shah, S., Kohl, T.A., Smith, G., Solano, Walter, Spitaleri, A., Supply, P., Steyn, A.J.C., Surve, U., Tahseen, S., Thuong, N.T.T., Thwaites, G., Todt, K., Trovato, A., Utpatel, C., Van Rie, A., Vijay, S., Warren, R., Werngren, J., Wijkander, M., Wilkinson, R.J., Wilson, D.J., Wintringer, P., Xiao, Y.-X., Yang, Y., Yanlin, Z., Yao, S.-Y., Zhu, B., The Zooniverse Volunteer Community, The CRyPTIC Consortium, Community, The Zooniverse Volunteer, Consortium, The CRyPTIC, Centre d’Infection et d’Immunité de Lille - INSERM U 1019 - UMR 9017 - UMR 8204 (CIIL), Institut Pasteur de Lille, Réseau International des Instituts Pasteur (RIIP)-Réseau International des Instituts Pasteur (RIIP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Lille-Centre Hospitalier Régional Universitaire [Lille] (CHRU Lille)-Centre National de la Recherche Scientifique (CNRS), and Wellcome Trust

Subjects
Volunteers, Model organisms, infectious disease, [SDV]Life Sciences [q-bio], Immunology, Antitubercular Agents, Infectious Disease, Microbial Sensitivity Tests, Zooniverse Volunteer Community, 0601 Biochemistry and Cell Biology, antibiotics, General Biochemistry, Genetics and Molecular Biology, Imaging, minimum inhibitory concentrations, antitubercular drugs, citizen science, M. tuberculosis, Humans, clinical microbiology, Human Biology & Physiology, General Immunology and Microbiology, CRyPTIC Consortium, Prevention, General Neuroscience, FOS: Clinical medicine, microbiology, BashTheBug, Mycobacterium tuberculosis, General Medicine, microdilution plates, Emerging Infectious Diseases, Infectious Diseases, Good Health and Well Being, tuberculosis, 5.1 Pharmaceuticals, photographs, Antimicrobial Resistance, Biochemistry and Cell Biology, Development of treatments and therapeutic interventions, Infection
Abstract

Tuberculosis is a respiratory disease that is treatable with antibiotics. An increasing prevalence of resistance means that to ensure a good treatment outcome it is desirable to test the susceptibility of each infection to different antibiotics. Conventionally, this is done by culturing a clinical sample and then exposing aliquots to a panel of antibiotics, each being present at a pre-determined concentration, thereby determining if the sample isresistant or susceptible to each sample. The minimum inhibitory concentration (MIC) of a drug is the lowestconcentration that inhibits growth and is a more useful quantity but requires each sample to be tested at a range ofconcentrations for each drug. Using 96-well broth micro dilution plates with each well containing a lyophilised pre-determined amount of an antibiotic is a convenient and cost-effective way to measure the MICs of several drugs at once for a clinical sample. Although accurate, this is still an expensive and slow process that requires highly-skilled and experienced laboratory scientists. Here we show that, through the BashTheBug project hosted on the Zooniverse citizen science platform, a crowd of volunteers can reproducibly and accurately determine the MICs for 13 drugs and that simply taking the median or mode of 11-17 independent classifications is sufficient. There is therefore a potential role for crowds to support (but not supplant) the role of experts in antibiotic susceptibility testing.Tuberculosis is a bacterial respiratory infection that kills about 1.4 million people worldwide each year. While antibiotics can cure the condition, the bacterium responsible for this disease

Published
2022
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3. Epidemiological cut-off values for a 96-well broth microdilution plate for high-throughput research antibiotic susceptibility testing of

Author

Fowler, P.W., Barilar, I., Battaglia, S., Borroni, E., Brandao, A.P., Brankin, A., Cabibbe, A.M., Carter, J., Cirillo, D.M., Claxton, P., Clifton, D.A., Cohen, T., Coronel, Jorge, Crook, D.W., Dreyer, V., Earle, S.G., Escuyer, V., Ferrazoli, L., Gao, G.F., Gardy, J., Gharbia, S., Ghisi, K.T., Ghodousi, A., Cruz, A.L.G., Grandjean, Louis, Grazian, C., Groenheit, R., Guthrie, J.L., He, W., Hoffmann, H., Hoosdally, S.J., Hunt, M., Iqbal, Z., Ismail, N.A., Jarrett, L., Joseph, L., Jou, R., Kambli, P., Khot, R., Knaggs, J., Koch, A., Kohlerschmidt, D., Kouchaki, S., Lachapelle, A.S., Lalvani, A., Lapierre, S.G., Laurenson, I.F., Letcher, B., Lin, W.-H., Liu, C., Liu, D., Malone, K.M., Mandal, A., Mansjö, M., Matias, D., Meintjes, G., de Freitas Mendes, F., Merker, M., Mihalic, M., Millard, J., Miotto, P., Mistry, N., Moore, David Alexander James, Musser, K.A., Ngcamu, D., Nhung, H.N., Niemann, S., Nilgiriwala, K.S., Nimmo, C., Okozi, N., Oliveira, R.S., Omar, S.V., Paton, N., Peto, T.E.A., Pinhata, J.M.W., Plesnik, S., Puyen, Z.M., Rabodoarivelo, M.S., Rakotosamimanana, N., Rancoita, P.M.V., Rathod, P., Robinson, E., Rodger, G., Rodrigues, C., Rodwell, T.C., Roohi, A., Santos-Lazaro, D., Shah, S., Kohl, T.A., Smith, G., Solano, Walter, Spitaleri, A., Supply, P., Surve, U., Tahseen, S., Thuong, N.T.T., Thwaites, G., Todt, K., Trovato, A., Utpatel, C., Van Rie, A., Vijay, S., Walker, T.M., Walker, A.S., Warren, R., Werngren, J., Wijkander, M., Wilkinson, R.J., Wilson, D.J., Wintringer, P., Xiao, Y.-X., Yang, Y., Yanlin, Z., Yao, S.-Y., Zhu, B., Consoritum, CRyPTIC, Walker, AS, and CRyPTIC Consortium

Subjects
microdilution, Pulmonary and Respiratory Medicine, tuberculosis, Respiratory, M. tuberculosis, Humans, Tuberculosis, Human medicine, infections, Microbial Sensitivity Tests, Mycobacterium tuberculosis, Anti-Bacterial Agents
Abstract

Drug susceptibility testing ofM. tuberculosisis rooted in a binary susceptible/resistant paradigm. While there are considerable advantages in measuring the minimum inhibitory concentrations (MICs) of a panel of drugs for an isolate, it is necessary to measure the epidemiological cut-off values (ECOFF/ECVs) to permit comparison with qualitative data. Here we present ECOFF/ECVs for 13 anti-tuberculosis compounds, including bedaquiline and delamanid, derived from 20 637 clinical isolates collected by 14 laboratories based in 11 countries on five continents. Each isolate was incubated for 14 days on a dry 96-well broth microdilution plate and then read. Resistance to most of the drugs due to prior exposure is expected and the MIC distributions for many of the compounds are complex, and therefore aphenotypicallywild-type population could not be defined. Since a majority of samples also underwent genetic sequencing, we defined agenotypicallywild-type population and measured the MIC of the 99th percentile by direct measurement andviafitting a Gaussian using interval regression. The proposed ECOFF/ECVs were then validated by comparing with the MIC distributions of high-confidence genetic variants that confer resistance and with qualitative drug susceptibility tests obtainedviathe Mycobacterial Growth Indicator Tube (MGIT) system or Microscopic-Observation Drug Susceptibility (MODS) assay. These ECOFF/ECVs will inform and encourage the more widespread adoption of broth microdilution: this is a cheap culture-based method that tests the susceptibility of 12–14 antibiotics on a single 96-well plate and so could help personalise the treatment of tuberculosis.

Published
2021

4. Antimicrobial susceptibility testing of Mycobacterium tuberculosis complex isolates – the EUCAST broth microdilution reference method for MIC determination

Author

Schön, T. (Thomas), Werngren, J. (Jim), Machado, D. (Diana), Borroni, E. (Emanuele), Wijkander, M. (Maria), Lina, G. (Gérard), Mouton, J.W. (Johan), Matuschek, E. (Erika), Kahlmeter, G., Giske, C.G. (Christian G.), Santin, M. (Miguel), Cirillo, D.M. (Daniela Maria), Viveiros, M. (Miguel), Cambau, E. (Emmanuelle), Schön, T. (Thomas), Werngren, J. (Jim), Machado, D. (Diana), Borroni, E. (Emanuele), Wijkander, M. (Maria), Lina, G. (Gérard), Mouton, J.W. (Johan), Matuschek, E. (Erika), Kahlmeter, G., Giske, C.G. (Christian G.), Santin, M. (Miguel), Cirillo, D.M. (Daniela Maria), Viveiros, M. (Miguel), and Cambau, E. (Emmanuelle)

Abstract

Scope: Several methods are used worldwide for antibiotic susceptibility testing (AST) for the Mycobacterium tuberculosis complex (MTBC). The variability in the results obtained with these methods hampers setting epidemiological cut-off (ECOFF) values and clinical breakpoints according to EUCAST guidelines. Methods for susceptibility testing and determination of the minimal inhibitory concentrations (MICs) need to be standardized for MTBC isolates for old and new agents. Our objective was to establish a standardized reference method for MIC determination for MTBC. Methods: The EUCAST antimycobacterial susceptibility testing subcommittee (AMST) compared protocols of MIC determination with regard to medium, inoculum preparation, antituberculous agent preparation, incubation, reading of the results and interpretation. Recommendations: The EUCAST reference method of MIC determination for MTBC is the broth microdilution method in Middlebrook 7H9-10% OADC medium. The final inoculum is a 105 CFU/mL suspension, obtained from a 10−2 dilution of a 0.5 McFarland suspension prepared after vortexing bacterial colonies with glass beads before suspending them in sterile water. The culture is maintained in a U-shaped 96-well polystyrene microtitre sterile plate with a lid incubated at 36° ± 1°C. Reading is done using an inverted mirror as soon as the 1:100 diluted control (i.e. 103 CFU/mL suspension) shows visual growth. The MIC, expressed in mg/L, is the lowest concentration that inhibits visual growth. Mycobacterium tuberculosis H37Rv ATCC 27294 is used as the reference strain and its targeted MIC values are within the range 0.03–0.12 for isoniazid, 0.12–0.5 for levofloxacin and 0.25–1 mg/L for amikacin. Conclusions: The EUCAST reference method for MTBC was endorsed by EUCAST after public consultation and will from now on be used to define EUCAST ECOFFs and clinical breakpoints. This reference method is not primarily intended to be used under routine conditions and the AST methods

Published
2020
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5. Antimicrobial susceptibility testing of Mycobacterium tuberculosis complex isolates – the EUCAST broth microdilution reference method for MIC determination

Author

Schön, T, Werngren, J, Machado, D, Borroni, E, Wijkander, M, Lina, G, Mouton, Johan, Matuschek, E, Kahlmeter, G, Giske, C, Santin, M, Cirillo, DM, Viveiros, M, Cambau, E, Schön, T, Werngren, J, Machado, D, Borroni, E, Wijkander, M, Lina, G, Mouton, Johan, Matuschek, E, Kahlmeter, G, Giske, C, Santin, M, Cirillo, DM, Viveiros, M, and Cambau, E

Published
2020

6. The role of familial factors and neuroticism in the association between exposure to offensive behaviors at work and long-term sickness absence due to common mental disorders - a prospective twin study.

Author

Wijkander M, Svedberg P, Narusyte J, Alaie I, Lindfors P, Xu T, and Magnusson Hanson LL

Subjects
Humans, Male, Female, Sweden epidemiology, Adult, Prospective Studies, Middle Aged, Workplace Violence statistics & numerical data, Workplace Violence psychology, Bullying psychology, Bullying statistics & numerical data, Neuroticism, Sick Leave statistics & numerical data, Mental Disorders epidemiology
Abstract

Objectives: The aim of this study was to investigate associations between exposure to work-related violence/threats and harassment, and future sickness absence (SA) due to common mental disorders (CMDs), taking familial factors (shared genetics and early-life environment) and neuroticism into account., Methods: The study sample included 8795 twin individuals from the Swedish Twin Project of Disability Pension and Sickness Absence (STODS), including survey data from the Study of Twin Adults: Genes and Environment (STAGE). Self-reported work-related violence and/or threats as well as work-related harassment (including bullying) and national register data on SA due to CMDs were analyzed using standard logistic regression, and conditional logistic regression among complete twin pairs discordant on exposures. Individuals were followed for a maximum of 13 years. Interactions between neuroticism and exposures were assessed using both multiplicative and additive interaction analyses., Results: Exposure to work-related violence/threats was associated with higher odds of SA due to CMDs when adjusting for age, sex, marital status, children, education, type of living area, work characteristics, and symptoms of depression and burnout (OR 2.11, 95% CI 1.52-2.95). Higher odds of SA due to CMDs were also found for exposure to harassment (OR 1.52, 95% CI 1.10-2.11) and a combined indicator of exposure to violence/threats and/or harassment (OR 1.98, 95% CI 1.52-2.59), compared with the unexposed. Analyses of twins discordant on exposure, using the unexposed co-twin as reference, showed reduced ORs. These ORs were still elevated but no longer statistically significant, potentially due to a lack of statistical power. No multiplicative interaction was found between neuroticism and exposure to work-related violence/threats, or harassment. However, a statistically significant additive interaction was found between neuroticism and exposure to violence/threats, indicating higher odds of SA due to CMDs in the group scoring lower on neuroticism., Conclusions: Exposure to work-related offensive behaviors was associated with SA due to CMDs. However, the results indicated that these associations may be partly confounded by familial factors. In addition, an interaction between exposure and neuroticism was suggested. Thus, when possible, future studies investigating associations and causality between offensive behaviors at work and mental health-related outcomes, should consider familial factors and neuroticism., (© 2024. The Author(s).)

Published
2024
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7. In vitro activity of new combinations of β-lactam and β-lactamase inhibitors against the Mycobacterium tuberculosis complex.

Author

Economou Lundeberg E, Andersson V, Wijkander M, Groenheit R, Mansjö M, Werngren J, Cortes T, Barilar I, Niemann S, Merker M, Köser CU, and Davies Forsman L

Abstract

As meropenem-clavulanic acid is recommended for the treatment of drug-resistant tuberculosis, the repurposing of new carbapenem combinations may provide new treatment options, including oral alternatives. Therefore, we studied the in vitro activities of meropenem-vaborbactam, meropenem-clavulanic acid, and tebipenem-clavulanic acid. One hundred nine Mycobacterium tuberculosis complex (MTBC) clinical isolates were tested, of which 69 were pan-susceptible and the remaining pyrazinamide- or multidrug-resistant. Broth microdilution MICs were determined using the EUCAST reference method. Meropenem and tebipenem were tested individually and in combination with vaborbactam 8 mg/L and clavulanic-acid 2 and 4 mg/L, respectively. Whole-genome sequencing was performed to explore resistance mechanisms. Clavulanic acid lowered the modal tebipenem MIC approximately 16-fold (from 16 to 1 mg/L). The modal meropenem MIC was reduced twofold by vaborbactam compared with an approximately eightfold decrease by clavulanic acid. The only previously described high-confidence carbapenem resistance mutation, crfA T62A, was shared by a subgroup of lineage 4.3.4.1 isolates and did not correlate with elevated MICs. The presence of a β-lactamase inhibitor reduced the MTBC MICs of tebipenem and meropenem. The resulting MIC distribution was lowest for the orally available drugs tebipenem-clavulanic acid. Whether this in vitro activity translates to similar or greater clinical efficacy of tebipenem-clavulanic acid compared with the currently WHO-endorsed meropenem-clavulanic acid requires clinical studies. IMPORTANCE Repurposing of already approved antibiotics, such as β-lactams in combination with β-lactamase inhibitors, may provide new treatment alternatives for drug-resistant tuberculosis. Meropenem-clavulanic acid was more active in vitro compared to meropenem-vaborbactam. Notably, tebipenem-clavulanic acid showed even better activity, raising the potential of an all-oral treatment option. Clinical data are needed to investigate whether the better in vitro activity of tebipenem-clavulanic acid correlates with greater clinical efficacy compared with the currently WHO-endorsed meropenem-clavulanic acid.

Published
2023
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8. Multicentre testing of the EUCAST broth microdilution reference method for MIC determination on Mycobacterium tuberculosis.

Author

Schön T, Werngren J, Machado D, Borroni E, Wijkander M, Lina G, Mouton J, Matuschek E, Kahlmeter G, Giske C, Santin M, Cirillo DM, Viveiros M, and Cambau E

Subjects
Amikacin pharmacology, Bacteriological Techniques, Humans, Isoniazid pharmacology, Levofloxacin pharmacology, Microbial Sensitivity Tests methods, Reproducibility of Results, Antitubercular Agents pharmacology, Microbial Sensitivity Tests standards, Mycobacterium tuberculosis drug effects
Abstract

Objectives: The first objective of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) subcommittee for antimycobacterial susceptibility testing (AMST), launched in 2016, was to set a reference method for determining the MICs of antituberculous agents, since many protocols are used worldwide and a consensus one is needed for the determination of microbiological breakpoints., Methods: During 2017 and 2018, MIC determination protocols were evaluated prospectively in a multicentre study within the four AMST laboratories. MIC results were obtained for isoniazid, levofloxacin and amikacin on the reference strain Mycobacterium tuberculosis H37Rv ATCC 27294. Broth microdilution (BMD) in Middlebrook 7H9 and solid medium dilution (SMD) in Middlebrook 7H10 were performed using two inoculum concentrations. MICs were interpreted with regard to visual and 99% inhibition after 7, 14 or 21 days of incubation for BMD and 21 days for SMD., Results: Following the EUCAST reference protocol, intra- and inter-assay agreements were within ±1 MIC dilution for >95% of the observations for the three drugs in both methods. MIC values, presented as MIC mode (range) for BMD and SMD respectively, were: 0.03 (0.015-0.06) mg/L and 0.12 (0.06-0.25) mg/L for isoniazid, 0.25 mg/L (0.25-0.5) and 0.5 mg/L (0.12-0.5) for levofloxacin, and 0.5 mg/L (0.5-1.0) and 0.5 mg/L (0.5-1.0) for amikacin., Conclusions: Both SMD and BMD were reproducible and eligible as a reference method for MIC determination of the Mycobacterium tuberculosis complex (MTBC). BMD was finally selected as the EUCAST reference method. From now on it will be used to set epidemiological cut-off values and clinical breakpoints of new and old antituberculous agents., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Published
2021
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9. Antimicrobial susceptibility testing of Mycobacterium tuberculosis complex isolates - the EUCAST broth microdilution reference method for MIC determination.

Author

Schön T, Werngren J, Machado D, Borroni E, Wijkander M, Lina G, Mouton J, Matuschek E, Kahlmeter G, Giske C, Santin M, Cirillo DM, Viveiros M, and Cambau E

Subjects
Humans, Microbial Viability drug effects, Mycobacterium tuberculosis drug effects, Practice Guidelines as Topic, Reference Standards, Anti-Bacterial Agents pharmacology, Microbial Sensitivity Tests standards, Mycobacterium tuberculosis growth & development
Abstract

Scope: Several methods are used worldwide for antibiotic susceptibility testing (AST) for the Mycobacterium tuberculosis complex (MTBC). The variability in the results obtained with these methods hampers setting epidemiological cut-off (ECOFF) values and clinical breakpoints according to EUCAST guidelines. Methods for susceptibility testing and determination of the minimal inhibitory concentrations (MICs) need to be standardized for MTBC isolates for old and new agents. Our objective was to establish a standardized reference method for MIC determination for MTBC., Methods: The EUCAST antimycobacterial susceptibility testing subcommittee (AMST) compared protocols of MIC determination with regard to medium, inoculum preparation, antituberculous agent preparation, incubation, reading of the results and interpretation., Recommendations: The EUCAST reference method of MIC determination for MTBC is the broth microdilution method in Middlebrook 7H9-10% OADC medium. The final inoculum is a 10 5  CFU/mL suspension, obtained from a 10 -2 dilution of a 0.5 McFarland suspension prepared after vortexing bacterial colonies with glass beads before suspending them in sterile water. The culture is maintained in a U-shaped 96-well polystyrene microtitre sterile plate with a lid incubated at 36° ± 1°C. Reading is done using an inverted mirror as soon as the 1:100 diluted control (i.e. 10 3  CFU/mL suspension) shows visual growth. The MIC, expressed in mg/L, is the lowest concentration that inhibits visual growth. Mycobacterium tuberculosis H37Rv ATCC 27294 is used as the reference strain and its targeted MIC values are within the range 0.03-0.12 for isoniazid, 0.12-0.5 for levofloxacin and 0.25-1 mg/L for amikacin., Conclusions: The EUCAST reference method for MTBC was endorsed by EUCAST after public consultation and will from now on be used to define EUCAST ECOFFs and clinical breakpoints. This reference method is not primarily intended to be used under routine conditions and the AST methods will need to be calibrated against this reference method to be used with EUCAST breakpoints., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Published
2020
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10. Detection of Mycobacterium tuberculosis pncA Mutations by the Nipro Genoscholar PZA-TB II Assay Compared to Conventional Sequencing.

Author

Willby MJ, Wijkander M, Havumaki J, Johnson K, Werngren J, Hoffner S, Denkinger CM, and Posey JE

Subjects
Antitubercular Agents pharmacology, Drug Resistance, Bacterial genetics, Humans, Microbial Sensitivity Tests methods, Mycobacterium tuberculosis drug effects, Promoter Regions, Genetic genetics, Pyrazinamide pharmacology, Tuberculosis, Multidrug-Resistant, Bacterial Proteins genetics, Biological Assay methods, Mutation genetics, Mycobacterium tuberculosis genetics
Abstract

Pyrazinamide (PZA) is a standard component of first-line treatment regimens for Mycobacterium tuberculosis and is included in treatment regimens for drug-resistant M. tuberculosis whenever possible. Therefore, it is imperative that susceptibility to PZA be assessed reliably prior to the initiation of therapy. Currently available growth-based PZA susceptibility tests are time-consuming, and results can be inconsistent. Molecular tests have been developed for most first-line antituberculosis drugs; however, a commercial molecular test is not yet available for rapid detection of PZA resistance. Recently, a line probe assay, the Nipro Genoscholar PZA-TB II assay, was developed for the detection of mutations within the pncA gene, including the promoter region, that are likely to lead to PZA resistance. The sensitivity and specificity of this assay were evaluated by two independent laboratories, using a combined total of 249 strains with mutations in pncA or its promoter and 21 strains with wild-type pncA Overall, the assay showed good sensitivity (93.2% [95% confidence interval, 89.3 to 95.8%]) and moderate specificity (91.2% [95% confidence interval, 77.0 to 97.0%]) for the identification of M. tuberculosis strains predicted to be resistant to PZA on the basis of the presence of mutations (excluding known PZA-susceptible mutations) in the pncA coding region or promoter. The assay shows promise for the molecular prediction of PZA resistance., (Copyright © 2017 American Society for Microbiology.)

Published
2017
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11. In vitro activity of AZD5847 against geographically diverse clinical isolates of Mycobacterium tuberculosis.

Author

Werngren J, Wijkander M, Perskvist N, Balasubramanian V, Sambandamurthy VK, Rodrigues C, and Hoffner S

Subjects
Drug Resistance, Multiple, Bacterial, Extensively Drug-Resistant Tuberculosis microbiology, Humans, Microbial Sensitivity Tests, Mycobacterium tuberculosis genetics, Mycobacterium tuberculosis isolation & purification, Tuberculosis, Pulmonary microbiology, Antitubercular Agents therapeutic use, Extensively Drug-Resistant Tuberculosis drug therapy, Mycobacterium tuberculosis drug effects, Oxazolidinones therapeutic use, Tuberculosis, Pulmonary drug therapy
Abstract

The MIC of the novel antituberculosis (anti-TB) drug AZD5847 was determined against 146 clinical isolates from diverse geographical regions, including eastern Europe, North America, Africa, and Asia, using the automated Bactec Mycobacterial Growth Indicator Tube (MGIT) 960 system. These isolates originated from specimen sources such as sputum, bronchial alveolar lavage fluid, pleural fluid, abscess material, lung biopsies, and feces. The overall MIC90 was 1.0 mg/liter (range, 0.125 to 4 mg/liter). The MICs of AZD5847 for isolates of Mycobacterium tuberculosis were similar among drug-sensitive strains, multidrug-resistant (MDR) strains, and extensively drug resistant (XDR) strains. The good in vitro activity of AZD5847 against M. tuberculosis and the lack of cross-resistance make this agent a promising anti-TB drug candidate., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)

Published
2014
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12. Multidrug-resistant Myobacterium tuberculosis caused by the Beijing genotype and a specific T1 genotype clone (SIT No. 266) is widely transmitted in Minsk.

Author

Zalutskaya A, Wijkander M, Jureen P, Skrahina A, and Hoffner S

Abstract

Setting: This study was performed in the city of Minsk in Belarus, where a very severe problem with MDR-TB was demonstrated in a recent drug resistant survey., Objective: The aim of this study was to use molecular typing of MDR and pan-susceptible clinical isolates of Mycobacterium tuberculosis to increase the understanding of the transmission patterns and possible differences between the strains causing susceptible and drug-resistant tuberculosis., Study Population and Methods: Consecutive isolates from pulmonary TB patients in Minsk were collected at the Belarusian National Reference Laboratory. Isolates found to be either pan-susceptible or MDR were included in the study, which totally comprised 81 MDR and 82 pan-susceptible clinical isolates. All isolates were characterized by spoligotyping. The major clusters were characterized using sequencing of the pncA gene., Results: Three out of four MDR cases were caused by one out of two drug-resistant clones of M. tuberculosis belonging to the Beijing and T1 genotypes, respectively. A single T1 clone, SIT No. 266, found exclusively in the MDR cohort, was shown to cause no less than 30% of all MDR-TB cases., Discussion: The findings indicate that the major cause of MDR-TB in Minsk is an ongoing transmission of certain already resistant M. tuberculosis strains., Conclusion: The significant transmission of MDR-TB in Minsk underlines the urgent need for strengthened infection control measures to limit the transmission in order to better control MDR-TB., (Copyright © 2013 Asian-African Society for Mycobacteriology. Published by Elsevier Ltd. All rights reserved.)

Published
2013
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