scholarly journals Transient drug-tolerance and permanent drug-resistance rely on the trehalose-catalytic shift in Mycobacterium tuberculosis

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Jae Jin Lee ◽  
Sun-Kyung Lee ◽  
Naomi Song ◽  
Temitope O. Nathan ◽  
Benjamin M. Swarts ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Drug Tolerance

scholarly journals Phase variation in Mycobacterium tuberculosis glpK produces transiently heritable drug tolerance

2019 ◽  
Author(s):  
Hassan Safi ◽  
Pooja Gopal ◽  
Subramanya Lingaraju ◽  
Shuyi Ma ◽  
Carly Levine ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Stress Responses ◽  
Phase Variation ◽  
Drug Tolerance ◽  
Prolonged Treatment ◽  
Frameshift Mutations ◽  
Minimal Inhibitory Concentrations ◽  
Tb Treatment

AbstractThe length and complexity of tuberculosis (TB) therapy, as well as the propensity of Mycobacterium tuberculosis to develop drug resistance, are major barriers to global TB control efforts. M. tuberculosis is known to have the ability to enter into a drug-tolerant state, which may explain many of these impediments to TB treatment. We have identified a novel mechanism of genetically encoded but rapidly reversible drug-tolerance in M. tuberculosis caused by transient frameshift mutations in a homopolymeric tract (HT) of seven cytosines (7C) in the glpK gene. Inactivating frameshift mutations associated with the 7C HT in glpK produce small colonies that exhibit heritable multi-drug increases in minimal inhibitory concentrations and decreases in drug-dependent killing; however, reversion back to a fully drug-susceptible large-colony phenotype occurs rapidly through the introduction of additional insertions or deletions in the same glpK HT region. These reversible frameshift mutations in the 7C HT of M. tuberculosis glpK occur in clinical isolates, accumulate in M. tuberculosis infected mice with further accumulation during drug treatment, and exhibit a reversible transcriptional profile including induction of dosR and sigH and repression of kstR regulons, similar to that observed in other in vitro models of M. tuberculosis tolerance. These results suggest that GlpK phase variation may contribute to drug-tolerance, treatment failure and relapse in human TB. Drugs effective against phase-variant M. tuberculosis may hasten TB treatment and improve cure rates.SIGNIFICANCEThe ability of M. tuberculosis to survive during prolonged treatment has been attributed to either transient stress responses or fixed heritable drug-resistance producing mutations. We show that phase-variation in the M. tuberculosis glpK gene represents a third type of resistance mechanism. The ability of these glpK mutants to grow slowly and then rapidly revert suggests that these transiently-heritable changes may also explain how a hidden population of drug-tolerant bacteria develops during TB treatment. As a genetically trackable cause of drug-tolerance, M. tuberculosis glpK mutants provides a unique opportunity to study these phenomena at a cellular and mechanistic level. These mutants could also be used for developing drugs that target tolerant populations, leading to more rapid and effective TB treatments.

scholarly journals Enhanced respiration prevents drug tolerance and drug resistance in Mycobacterium tuberculosis

2017 ◽  
Vol 114 (17) ◽  
pp. 4495-4500 ◽  
Author(s):  
Catherine Vilchèze ◽  
Travis Hartman ◽  
Brian Weinrick ◽  
Paras Jain ◽  
Torin R. Weisbrod ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Cell Formation ◽  
Drug Tolerance ◽  
Drug Resistant ◽  
Tuberculosis Control ◽  
Persister Cells ◽  
Enhanced Production ◽  
Resistant Mutants ◽  
Reduced State

Persistence, manifested as drug tolerance, represents a significant obstacle to global tuberculosis control. The bactericidal drugs isoniazid and rifampicin kill greater than 99% of exponentially growing Mycobacterium tuberculosis (Mtb) cells, but the remaining cells are persisters, cells with decreased metabolic rate, refractory to killing by these drugs, and able to generate drug-resistant mutants. We discovered that the combination of cysteine or other small thiols with either isoniazid or rifampicin prevents the formation of drug-tolerant and drug-resistant cells in Mtb cultures. This effect was concentration- and time-dependent, relying on increased oxygen consumption that triggered enhanced production of reactive oxygen species. In infected murine macrophages, the addition of N-acetylcysteine to isoniazid treatment potentiated the killing of Mtb. Furthermore, we demonstrate that the addition of small thiols to Mtb drug treatment shifted the menaquinol/menaquinone balance toward a reduced state that stimulates Mtb respiration and converts persister cells to metabolically active cells. This prevention of both persister cell formation and drug resistance leads ultimately to mycobacterial cell death. Strategies to enhance respiration and initiate oxidative damage should improve tuberculosis chemotherapies.

scholarly journals High efflux pump activity and gene expression at baseline linked to poor tuberculosis treatment outcomes

2017 ◽  
Vol 6 (1) ◽  
pp. 8-17
Author(s):  
S. Mazando ◽  
C. Zimudzi ◽  
M. Zimba ◽  
S. Sande ◽  
M. Gundidza ◽  
...  
Keyword(s):  
Gene Expression ◽  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Ethidium Bromide ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Drug Tolerance ◽  
Tuberculosis Treatment ◽  
Expression Levels ◽  
Pump Activity

Phenotypic TB drug resistance, also known as drug tolerance, has been previously attributed to slowed bacterial growth in vivo. The increased activity and expression of efflux systems can lower the intracellular concentration of many antibiotics thus reducing their efficacy. We hypothesized that efflux pump activation and expression could be a risk factor for TB drug tolerance in patients initiated on treatment. Analyses of gene expression levels of six select efflux pumps associated with drug tolerance in Mycobacterium tuberculosis and its correlation with the cell’s ability to efflux ethidium bromide (a common efflux substrate) were assayed. Efflux pump gene expression differed significantly between the strains from treatment failures and treatment successes. Efflux of ethidium bromide by M. tuberculosis isolates revealed that isolates from treatment failures rapidly efflux ethidium bromide more than isolates from treatment successes or the H37Rv control strains. The efflux pumps efpA, jefA (Rv2459c), Rv1258c, p55 and mmpL7 may have a role in TB drug tolerance. Quantifying the expression levels of M. tuberculosis efflux pump genes may be a new method to diagnose clinically persistent tuberculosis. High efflux pump activity and expression at baseline can be associated with tuberculosis treatment failure even when the Mycobacterium tuberculosis does not have established resistance mutations.Journal of Medical and Biomedical Sciences (2017) 6(1), 8-17Keywords: drug resistance, Efflux, Mycobacterium tuberculosis, expression, treatment outcome

scholarly journals Rifampicin exposure reveals within-host Mycobacterium tuberculosis diversity in patients with delayed culture conversion

2021 ◽  
Vol 17 (6) ◽  
pp. e1009643
Author(s):  
Charlotte Genestet ◽  
Elisabeth Hodille ◽  
Alexia Barbry ◽  
Jean-Luc Berland ◽  
Jonathan Hoffmann ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Drug Tolerance ◽  
Clinical Isolates ◽  
Nucleotide Polymorphisms ◽  
Macrophage Infection ◽  
Tb Treatment ◽  
Increased Risk ◽  
Emergence Of Resistance ◽  
Culture Conversion

Mycobacterium tuberculosis (Mtb) genetic micro-diversity in clinical isolates may underline mycobacterial adaptation to tuberculosis (TB) infection and provide insights to anti-TB treatment response and emergence of resistance. Herein we followed within-host evolution of Mtb clinical isolates in two cohorts of TB patients, either with delayed Mtb culture conversion (> 2 months), or with fast culture conversion (< 2 months). We captured the genetic diversity of Mtb isolates obtained in each patient, by focusing on minor variants detected as unfixed single nucleotide polymorphisms (SNPs). To unmask antibiotic tolerant sub-populations, we exposed these isolates to rifampicin (RIF) prior to whole genome sequencing (WGS) analysis. Thanks to WGS, we detected at least 1 unfixed SNP within the Mtb isolates for 9/15 patients with delayed culture conversion, and non-synonymous (ns) SNPs for 8/15 patients. Furthermore, RIF exposure revealed 9 additional unfixed nsSNP from 6/15 isolates unlinked to drug resistance. By contrast, in the fast culture conversion cohort, RIF exposure only revealed 2 unfixed nsSNP from 2/20 patients. To better understand the dynamics of Mtb micro-diversity, we investigated the variant composition of a persistent Mtb clinical isolate before and after controlled stress experiments mimicking the course of TB disease. A minor variant, featuring a particular mycocerosates profile, became enriched during both RIF exposure and macrophage infection. The variant was associated with drug tolerance and intracellular persistence, consistent with the pharmacological modeling predicting increased risk of treatment failure. A thorough study of such variants not necessarily linked to canonical drug-resistance, but which are prone to promote anti-TB drug tolerance, may be crucial to prevent the subsequent emergence of resistance. Taken together, the present findings support the further exploration of Mtb micro-diversity as a promising tool to detect patients at risk of poorly responding to anti-TB treatment, ultimately allowing improved and personalized TB management.

Current insights into the chemistry and antitubercular potential of benzimidazole and imidazole derivatives

2020 ◽  
Vol 20 ◽  
Author(s):  
Deepa Parwani ◽  
Sushanta Bhattacharya ◽  
Akash Rathore ◽  
Chaitali Mallick ◽  
Vivek Asati ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Multi Drug Resistance ◽  
Benzimidazole Derivatives ◽  
Duration Of Treatment ◽  
Structure Activity ◽  
Mdr Tb ◽  
Low Toxicity ◽  
Extensively Drug Resistance ◽  
Improved Characteristics

: Tuberculosis is a disease caused by Mycobacterium tuberculosis (Mtb), affecting millions of people worldwide. The emergence of drug resistance is a major problem in the successful treatment of tuberculosis. Due to the commencement of MDR-TB (multi-drug resistance) and XDR-TB (extensively drug resistance), there is a crucial need for the development of novel anti-tubercular agents with improved characteristics such as low toxicity, enhanced inhibitory activity and short duration of treatment. In this direction, various heterocyclic compounds have been synthesized and screened against Mycobacterium tuberculosis. Among them, benzimidazole and imidazole containing derivatives found to have potential anti-tubercular activity. The present review focuses on various imidazole and benzimidazole derivatives (from 2015-2019) with their structure activity relationships in the treatment of tuberculosis.

scholarly journals Analysis of drug resistance and mutation profiles in Mycobacterium tuberculosis isolates in a surveillance site in Beijing, China

2021 ◽  
Vol 49 (1) ◽  
pp. 030006052098493
Author(s):  
Jie Zhang ◽  
Yixuan Ren ◽  
Liping Pan ◽  
Junli Yi ◽  
Tong Guan ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Drug Testing ◽  
Multidrug Resistant ◽  
High Rate ◽  
Drug Resistant ◽  
Surveillance Site ◽  
Mdr Tb ◽  
Previously Treated Patients ◽  
Beijing China

Objective This study analyzed drug resistance and mutations profiles in Mycobacterium tuberculosis isolates in a surveillance site in Huairou District, Beijing, China. Methods The proportion method was used to assess drug resistance profiles for four first-line and seven second-line anti-tuberculosis (TB) drugs. Molecular line probe assays were used for the rapid detection of resistance to rifampicin (RIF) and isoniazid (INH). Results Among 235 strains of M. tuberculosis, 79 (33.6%) isolates were resistant to one or more drugs. The isolates included 18 monoresistant (7.7%), 19 polyresistant (8.1%), 28 RIF-resistant (11.9%), 24 multidrug-resistant (MDR) (10.2%), 7 pre-extensively drug-resistant (XDR, 3.0%), and 2 XDR strains (0.9%). A higher rate of MDR-TB was detected among previously treated patients than among patients with newly diagnosed TB (34.5% vs. 6.8%). The majority (62.5%) of RIF-resistant isolates exhibited a mutation at S531L in the DNA-dependent RNA polymerase gene. Meanwhile, 62.9% of INH-resistant isolates carried a mutation at S315T1 in the katG gene. Conclusion Our results confirmed the high rate of drug-resistant TB, especially MDR-TB, in Huairou District, Beijing, China. Therefore, detailed drug testing is crucial in the evaluation of MDR-TB treatment.

scholarly journals Biofilm formation in the lung contributes to virulence and drug tolerance of Mycobacterium tuberculosis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Poushali Chakraborty ◽  
Sapna Bajeli ◽  
Deepak Kaushal ◽  
Bishan Dass Radotra ◽  
Ashwani Kumar
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Immune System ◽  
Biofilm Formation ◽  
Antimycobacterial Activity ◽  
Drug Tolerance ◽  
Host Immune System ◽  
Tissue Sections ◽  
Slow Growing

AbstractTuberculosis is a chronic disease that displays several features commonly associated with biofilm-associated infections: immune system evasion, antibiotic treatment failures, and recurrence of infection. However, although Mycobacterium tuberculosis (Mtb) can form cellulose-containing biofilms in vitro, it remains unclear whether biofilms are formed during infection in vivo. Here, we demonstrate the formation of Mtb biofilms in animal models of infection and in patients, and that biofilm formation can contribute to drug tolerance. First, we show that cellulose is also a structural component of the extracellular matrix of in vitro biofilms of fast and slow-growing nontuberculous mycobacteria. Then, we use cellulose as a biomarker to detect Mtb biofilms in the lungs of experimentally infected mice and non-human primates, as well as in lung tissue sections obtained from patients with tuberculosis. Mtb strains defective in biofilm formation are attenuated for survival in mice, suggesting that biofilms protect bacilli from the host immune system. Furthermore, the administration of nebulized cellulase enhances the antimycobacterial activity of isoniazid and rifampicin in infected mice, supporting a role for biofilms in phenotypic drug tolerance. Our findings thus indicate that Mtb biofilms are relevant to human tuberculosis.

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