Origin and Dynamics of Mycobacterium tuberculosis Subpopulations That Predictably Generate Drug Tolerance and Resistance

ABSTRACT Initial responses to tuberculosis treatment are poor predictors of final therapeutic outcomes in drug-susceptible disease, suggesting that treatment success depends on features that are hidden within a small minority of the overall infecting Mycobacterium tuberculosis population. We develop...

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Main Authors: Jees Sebastian, Anooja Thomas, Carly Levine, Riju Shrestha, Shawn Levy, Hassan Safi, Sri Ram Pentakota, Pradeep Kumar, David Alland
Format: Article
Language:English
Published: American Society for Microbiology 2022-12-01
Series:mBio
Subjects:
Online Access:https://journals.asm.org/doi/10.1128/mbio.02795-22
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author Jees Sebastian
Anooja Thomas
Carly Levine
Riju Shrestha
Shawn Levy
Hassan Safi
Sri Ram Pentakota
Pradeep Kumar
David Alland
author_facet Jees Sebastian
Anooja Thomas
Carly Levine
Riju Shrestha
Shawn Levy
Hassan Safi
Sri Ram Pentakota
Pradeep Kumar
David Alland
author_sort Jees Sebastian
collection DOAJ
description ABSTRACT Initial responses to tuberculosis treatment are poor predictors of final therapeutic outcomes in drug-susceptible disease, suggesting that treatment success depends on features that are hidden within a small minority of the overall infecting Mycobacterium tuberculosis population. We developed a multitranswell robotic system to perform numerous parallel cultures of genetically barcoded M. tuberculosis exposed to steady-state concentrations of rifampicin to uncover these difficult-to-eliminate minority populations. We found that tolerance emerged repeatedly from at least two subpopulations of barcoded cells, namely, one that could not grow on solid agar media and a second that could form colonies, but whose kill curves diverged from the general bacterial population within 4 and 16 days of drug exposure, respectively. These tolerant subpopulations reproducibly passed through a phase characterized by multiple unfixed resistance mutations followed by emergent drug resistance in some cultures. Barcodes associated with drug resistance identified an especially privileged subpopulation that was rarely eliminated despite 20 days of drug treatment even in cultures that did not contain any drug-resistant mutants. The association of this evolutionary scenario with a defined subset of barcodes across multiple independent cultures suggested a transiently heritable phenotype, and indeed, glpK phase variation mutants were associated with up to 16% of the resistant cultures. Drug tolerance and resistance were eliminated in a ΔruvA mutant, consistent with the importance of bacterial stress responses. This work provides a window into the origin and dynamics of bacterial drug-tolerant subpopulations whose elimination may be critical for developing rapid and resistance-free cures. IMPORTANCE Tuberculosis is unusual among bacterial diseases in that treatments which can rapidly resolve symptoms do not predictably lead to a durable cure unless treatment is continued for months after all clinical and microbiological signs of disease have been eradicated. Using a novel steady-state antibiotic exposure system combined with chromosomal barcoding, we identified small hidden Mycobacterium tuberculosis subpopulations that repeatedly enter a state of drug tolerance with a predisposition to develop fixed drug resistance after first developing a cloud of unfixed resistance mutations. The existence of these difficult-to-eradicate subpopulations may explain the need for extended treatment regimen for tuberculosis. Their identification provides opportunities to test genetic and therapeutic approaches that may result in shorter and more effective TB treatments.
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spelling doaj.art-90002e1d81ba405c98f4bd7398680b802022-12-22T04:42:14ZengAmerican Society for MicrobiologymBio2150-75112022-12-0113610.1128/mbio.02795-22Origin and Dynamics of Mycobacterium tuberculosis Subpopulations That Predictably Generate Drug Tolerance and ResistanceJees Sebastian0Anooja Thomas1Carly Levine2Riju Shrestha3Shawn Levy4Hassan Safi5Sri Ram Pentakota6Pradeep Kumar7David Alland8Department of Medicine, Division of Infectious Disease, Ruy V. Lourenco Center for the Study of Emerging and Re-emerging Pathogens, Rutgers New Jersey Medical School, Newark, New Jersey, USADepartment of Hydrology, Indian Institute of Technology, Roorkee, Uttarakhand, IndiaDepartment of Medicine, Division of Infectious Disease, Ruy V. Lourenco Center for the Study of Emerging and Re-emerging Pathogens, Rutgers New Jersey Medical School, Newark, New Jersey, USADepartment of Medicine, Division of Infectious Disease, Ruy V. Lourenco Center for the Study of Emerging and Re-emerging Pathogens, Rutgers New Jersey Medical School, Newark, New Jersey, USAGenomics Services Laboratory, HudsonAlpha Institute for Biotechnology, Huntsville, Alabama, USADepartment of Medicine, Division of Infectious Disease, Ruy V. Lourenco Center for the Study of Emerging and Re-emerging Pathogens, Rutgers New Jersey Medical School, Newark, New Jersey, USADepartment of Surgery, Rutgers New Jersey Medical School, Newark, New Jersey, USADepartment of Medicine, Division of Infectious Disease, Ruy V. Lourenco Center for the Study of Emerging and Re-emerging Pathogens, Rutgers New Jersey Medical School, Newark, New Jersey, USADepartment of Medicine, Division of Infectious Disease, Ruy V. Lourenco Center for the Study of Emerging and Re-emerging Pathogens, Rutgers New Jersey Medical School, Newark, New Jersey, USAABSTRACT Initial responses to tuberculosis treatment are poor predictors of final therapeutic outcomes in drug-susceptible disease, suggesting that treatment success depends on features that are hidden within a small minority of the overall infecting Mycobacterium tuberculosis population. We developed a multitranswell robotic system to perform numerous parallel cultures of genetically barcoded M. tuberculosis exposed to steady-state concentrations of rifampicin to uncover these difficult-to-eliminate minority populations. We found that tolerance emerged repeatedly from at least two subpopulations of barcoded cells, namely, one that could not grow on solid agar media and a second that could form colonies, but whose kill curves diverged from the general bacterial population within 4 and 16 days of drug exposure, respectively. These tolerant subpopulations reproducibly passed through a phase characterized by multiple unfixed resistance mutations followed by emergent drug resistance in some cultures. Barcodes associated with drug resistance identified an especially privileged subpopulation that was rarely eliminated despite 20 days of drug treatment even in cultures that did not contain any drug-resistant mutants. The association of this evolutionary scenario with a defined subset of barcodes across multiple independent cultures suggested a transiently heritable phenotype, and indeed, glpK phase variation mutants were associated with up to 16% of the resistant cultures. Drug tolerance and resistance were eliminated in a ΔruvA mutant, consistent with the importance of bacterial stress responses. This work provides a window into the origin and dynamics of bacterial drug-tolerant subpopulations whose elimination may be critical for developing rapid and resistance-free cures. IMPORTANCE Tuberculosis is unusual among bacterial diseases in that treatments which can rapidly resolve symptoms do not predictably lead to a durable cure unless treatment is continued for months after all clinical and microbiological signs of disease have been eradicated. Using a novel steady-state antibiotic exposure system combined with chromosomal barcoding, we identified small hidden Mycobacterium tuberculosis subpopulations that repeatedly enter a state of drug tolerance with a predisposition to develop fixed drug resistance after first developing a cloud of unfixed resistance mutations. The existence of these difficult-to-eradicate subpopulations may explain the need for extended treatment regimen for tuberculosis. Their identification provides opportunities to test genetic and therapeutic approaches that may result in shorter and more effective TB treatments.https://journals.asm.org/doi/10.1128/mbio.02795-22Mycobacterium tuberculosisantibiotic toleranceantibiotic resistancechromosomal barcoding
spellingShingle Jees Sebastian
Anooja Thomas
Carly Levine
Riju Shrestha
Shawn Levy
Hassan Safi
Sri Ram Pentakota
Pradeep Kumar
David Alland
Origin and Dynamics of Mycobacterium tuberculosis Subpopulations That Predictably Generate Drug Tolerance and Resistance
mBio
Mycobacterium tuberculosis
antibiotic tolerance
antibiotic resistance
chromosomal barcoding
title Origin and Dynamics of Mycobacterium tuberculosis Subpopulations That Predictably Generate Drug Tolerance and Resistance
title_full Origin and Dynamics of Mycobacterium tuberculosis Subpopulations That Predictably Generate Drug Tolerance and Resistance
title_fullStr Origin and Dynamics of Mycobacterium tuberculosis Subpopulations That Predictably Generate Drug Tolerance and Resistance
title_full_unstemmed Origin and Dynamics of Mycobacterium tuberculosis Subpopulations That Predictably Generate Drug Tolerance and Resistance
title_short Origin and Dynamics of Mycobacterium tuberculosis Subpopulations That Predictably Generate Drug Tolerance and Resistance
title_sort origin and dynamics of mycobacterium tuberculosis subpopulations that predictably generate drug tolerance and resistance
topic Mycobacterium tuberculosis
antibiotic tolerance
antibiotic resistance
chromosomal barcoding
url https://journals.asm.org/doi/10.1128/mbio.02795-22
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