New Evidence for the Complexity of the Population Structure of <i>Mycobacterium tuberculosis</i> Increases the Diagnostic and Biologic Challenges

Dartois, Véronique; Saito, Kihachi; Warrier, Thulasi; Nathan, Carl

doi:10.1164/rccm.201607-1431ed

Cited by 25 publications

(18 citation statements)

References 11 publications

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“…One subpopulation with potentially high clinical relevance is a subset of cells that are metabolically viable but do not replicate, even after being returned to growth-permissive culture conditions. Phenotypically similar subpopulations of "differentially culturable tubercle bacilli" (DCTB), which could not form CFU when cultured on standard solid media but could be grown after exposure to liquid media supplemented with fresh M. tuberculosis culture filtrates, have been found in sputum samples of TB patients and sputum culture-negative, smearnegative individuals (63). The DCTB subpopulation appears to be phenotypically heterogeneous, as different subsets of DCTB replicate differentially when exposed to medium supplementations of resuscitation-promoting factors.…”

Section: Bacterial Pathogenesis and Immune Response Pathogenesis Of Imentioning

confidence: 99%

Incipient and Subclinical Tuberculosis: a Clinical Review of Early Stages and Progression of Infection

et al. 2018

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SUMMARYTuberculosis (TB) is the leading infectious cause of mortality worldwide, due in part to a limited understanding of its clinical pathogenic spectrum of infection and disease. Historically, scientific research, diagnostic testing, and drug treatment have focused on addressing one of two disease states: latent TB infection or active TB disease. Recent research has clearly demonstrated that human TB infection, from latent infection to active disease, exists within a continuous spectrum of metabolic bacterial activity and antagonistic immunological responses. This revised understanding leads us to propose two additional clinical states: incipient and subclinical TB. The recognition of incipient and subclinical TB, which helps divide latent and active TB along the clinical disease spectrum, provides opportunities for the development of diagnostic and therapeutic interventions to prevent progression to active TB disease and transmission of TB bacilli. In this report, we review the current understanding of the pathogenesis, immunology, clinical epidemiology, diagnosis, treatment, and prevention of both incipient and subclinical TB, two emerging clinical states of an ancient bacterium.

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Section: Bacterial Pathogenesis and Immune Response Pathogenesis Of Imentioning

confidence: 99%

Incipient and Subclinical Tuberculosis: a Clinical Review of Early Stages and Progression of Infection

et al. 2018

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“…With the existence of DD Mtb in human subjects now reported by independent groups, it is timely to confront conceptual and technical challenges that DD Mtb poses for the biology, experimental therapeutics, and clinical management of TB (15). A deeper understanding of the phenotype of such cells would greatly aid the development of simpler methods of enumerating them and discovering drugs that kill them.…”

Section: Significancementioning

confidence: 99%

Rifamycin action on RNA polymerase in antibiotic-tolerant Mycobacterium tuberculosis results in differentially detectable populations

Saito

Warrier

Somersan-Karakaya

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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110

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Mycobacterium tuberculosis (Mtb) encounters stresses during the pathogenesis and treatment of tuberculosis (TB) that can suppress replication of the bacteria and render them phenotypically tolerant to most available drugs. Where studied, the majority of Mtb in the sputum of most untreated subjects with active TB have been found to be nonreplicating by the criterion that they do not grow as colony-forming units (cfus) when plated on agar. However, these cells are viable because they grow when diluted in liquid media. A method for generating such "differentially detectable" (DD) Mtb in vitro would aid studies of the biology and drug susceptibility of this population, but lack of independent confirmation of reported methods has contributed to skepticism about their existence. Here, we identified confounding artifacts that, when avoided, allowed development of a reliable method of producing cultures of ≥90% DD Mtb in starved cells. We then characterized several drugs according to whether they contribute to the generation of DD Mtb or kill them. Of the agents tested, rifamycins led to DD Mtb generation, an effect lacking in a rifampin-resistant strain with a mutation in rpoB, which encodes the canonical rifampin target, the β subunit of RNA polymerase. In contrast, thioridazine did not generate DD Mtb from starved cells but killed those generated by rifampin.Mycobacterium tuberculosis | differentially detectable | phenotypic tolerance | rifampin | thioridazine

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“…This is illustrated by prior work that demonstrated the presence of differentially culturable tubercle bacteria (DCTB) in sputum that do not grow on solid media and are detected only in liquid media supplemented with culture filtrate (CF) 3 , 6 . This demonstrates that TB infection presents with a much higher level of bacterial phenotypic complexity than previously thought and a deeper understanding of the clinical relevance of DCTB populations is vital for the advancement of improved TB diagnosis and development of novel drug regimens 4 .…”

Section: Introductionmentioning

confidence: 96%

Detection of differentially culturable tubercle bacteria in sputum using mycobacterial culture filtrates

Gordhan

Peters

McIvor

et al. 2021

Sci Rep

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Rapid detection of tuberculosis (TB) infection is paramount to curb further transmission. The gold standard for this remains mycobacterial culture, however emerging evidence confirms the presence of differentially culturable tubercle bacteria (DCTB) in clinical specimens. These bacteria do not grow under standard culture conditions and require the presence of culture filtrate (CF), from axenic cultures of Mycobacterium tuberculosis (Mtb), to emerge. It has been hypothesized that molecules such as resuscitation promoting factors (Rpfs), fatty acids and cyclic-AMP (cAMP) present in CF are responsible for the growth stimulatory activity. Herein, we tested the ability of CF from the non-pathogenic bacterium Mycobacterium smegmatis (Msm) to stimulate the growth of DCTB, as this organism provides a more tractable source of CF. We also interrogated the role of Mtb Rpfs in stimulation of DCTB by creating recombinant strains of Msm that express Mtb rpf genes in various combinations. CF derived from this panel of strains was tested on sputum from individuals with drug susceptible TB prior to treatment. CF from wild type Msm did not enable detection of DCTB in a manner akin to Mtb CF preparations and whilst the addition of RpfABMtb and RpfABCDEMtb to an Msm mutant devoid of its native rpfs did improve detection of DCTB compared to the no CF control, it was not statistically different to the empty vector control. To further investigate the role of Rpfs, we compared the growth stimulatory activity of CF from Mtb, with and without Rpfs and found these to be equivalent. Next, we tested chemically diverse fatty acids and cAMP for growth stimulation and whilst some selective stimulatory effect was observed, this was not significantly higher than the media control and not comparable to CF. Together, these data indicate that the growth stimulatory effect observed with Mtb CF is most likely the result of a combination of factors. Future work aimed at identifying the nature of these growth stimulatory molecules may facilitate improvement of culture-based diagnostics for TB.

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New Evidence for the Complexity of the Population Structure of Mycobacterium tuberculosis Increases the Diagnostic and Biologic Challenges

Cited by 25 publications

References 11 publications

Incipient and Subclinical Tuberculosis: a Clinical Review of Early Stages and Progression of Infection

Incipient and Subclinical Tuberculosis: a Clinical Review of Early Stages and Progression of Infection

Rifamycin action on RNA polymerase in antibiotic-tolerant Mycobacterium tuberculosis results in differentially detectable populations

Detection of differentially culturable tubercle bacteria in sputum using mycobacterial culture filtrates

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