Project description:The emergence of drug resistance among tuberculosis (TB) patients is often associated with their non-compliance to the length of the chemotherapy, which can reach up to 2 years for the treatment of multi-drug-resistant (MDR) TB. Drugs that would kill TB faster and would not lead to the development of drug resistance could shorten chemotherapy significantly. In Escherichia coli, the common mechanism of cell death by bactericidal antibiotics is the generation of highly reactive hydroxyl radicals via the Fenton reaction. Since ascorbic acid (vitamin C) is known to drive the Fenton reaction, we tested whether the Fenton reaction could lead to a bactericidal event in Mycobacterium tuberculosis by treating M. tuberculosis cultures with vitamin C. Here, we report that the addition of vitamin C to drug-susceptible, MDR and extensively drug-resistant (XDR) M. tuberculosis strains results in sterilization of the cultures in vitro. We show that the sterilizing effect of vitamin C on M. tuberculosis was dependent on the production of high ferrous ion levels and reactive oxygen species. Although, this potent sterilizing activity of vitamin C against M. tuberculosis in vitro was not observed in mice, we believe this activity needs further investigation.
Project description:The emergence of drug resistance among tuberculosis (TB) patients is often associated with their non-compliance to the length of the chemotherapy, which can reach up to 2 years for the treatment of multi-drug-resistant (MDR) TB. Drugs that would kill TB faster and would not lead to the development of drug resistance could shorten chemotherapy significantly. In Escherichia coli, the common mechanism of cell death by bactericidal antibiotics is the generation of highly reactive hydroxyl radicals via the Fenton reaction. Since ascorbic acid (vitamin C) is known to drive the Fenton reaction, we tested whether the Fenton reaction could lead to a bactericidal event in Mycobacterium tuberculosis by treating M. tuberculosis cultures with vitamin C. Here, we report that the addition of vitamin C to drug-susceptible, MDR and extensively drug-resistant (XDR) M. tuberculosis strains results in sterilization of the cultures in vitro. We show that the sterilizing effect of vitamin C on M. tuberculosis was dependent on the production of high ferrous ion levels and reactive oxygen species. Although, this potent sterilizing activity of vitamin C against M. tuberculosis in vitro was not observed in mice, we believe this activity needs further investigation. Comparison of vitamin C treated Mycobacterium tuberculosis transcriptome relative to untreated; Three biological replicates, second is a dye flip
Project description:The lengthy and complicated multidrug therapy currently available to treat active tuberculosis (TB) infection has contributed to medical non-adherence and the emerging problems of multidrug-resistant (MDR)- and extensively drug-resistant (XDR)-TB, which are particularly deadly in the setting of HIV co-infection. The prolonged therapy required to eradicate TB infection is believed to reflect the ability of Mycobacterium tuberculosis (Mtb) to persist within host necrotic granulomas in a non-replicating state characterized by antibiotic tolerance to bactericidal drugs, which predominantly target actively dividing tubercle bacilli. The stringent response enzyme, RelMtb, is essential for Mtb survival under physiologically relevant stress conditions in vitro and in the lungs of mice and guinea pigs. A library of over 2 million compounds was screened in RelMtb-inhibition assays and whole-cell screens under conditions in which RelMtb is essential. A total of 178 RelMtb inhibitor candidates, representing 18 unique scaffolds, were identified and 39 compounds were tested against nutrient-starved wild-type Mtb. The antibiotic susceptibility of a relMtb deletion mutant (Δrel) was studied during nutrient starvation and chronic infection in mice, and isoniazid and RelMtb inhibitor candidates were tested for synergy against nutrient-starved wild-type Mtb and Δrel using checkerboard assays. The minimum bactericidal concentration of isoniazid was 500-fold lower against Δrel relative to wild type during nutrient starvation, and the potent bactericidal activity of isoniazid was maintained against Δrel during chronic infection in the lungs of mice. Inhibition of RelMtb appears to be a promising new approach to target Mtb persisters, with the potential to shorten the duration of treatment for drug-susceptible and drug-resistant TB. We used microarray to characterize the transcriptomic profiles of the wild type and Δrel during nutrient starvation. The RelMtb inhibitor, (E)-4-(3-methyl-4-(2-(4-methylthiazol-5-yl)ethoxy)styryl)benzoic acid, killed wild-type Mtb and prevented isoniazid tolerance during nutrient starvation. Treatment of nutrient-starved wild-type with the RelMtb inhibitor led to downregulation of the RelMtb regulon. Transcriptomic analysis revealed an altered gene expression in Δrel and wild-type treated with RelMtb inhibitor during nutrient starvation.
Project description:Rifampicin plays an important role during tuberculosis treatment, which historically contributed for shortening therapy; however, rifampicin resistance has been the intersection for the definition of multi (MDR-TB) and extensively (XDR-TB) resistant outcomes. A key aspect which has contributed for investigations of drug action/resistance is the understanding of the dynamic genome expression, as that analyzed by Proteomics. Proteins from the reference strain, Mycobacterium tuberculosis H37Rv were extracted after 12, 24 and 48 hours over rifampicin challenge at the minimal inhibitory concentration (0.03 μg•mL-1) and identified by LC-MS.
Project description:Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), latently infects one quarter of the world’s population. The rise of multidrug resistant (MDR) Mtb infections worldwide presents a significant obstacle to curb TB globally. While human studies report dysregulated immune responses in MDR TB patients, there is a lack of clear understanding of the host-pathogen interactions following MDR Mtb infection. We recently showed that Mtb carrying a rifampicin drug resistance (RDR)-conferring single nucleotide polymorphism in the RNA polymerase-B gene (Mtb rpoB-H445Y) can modulate host macrophage metabolic reprogramming by production of Type I IFNs. Here, using a mouse model, we have characterized the host immune response in vivo following RDR Mtb infection. We show that despite establishment of Mtb infection in the lung and dissemination to the peripheral organs, lung myeloid and lymphoid immune responses to RDR Mtb is suppressed through a Type I IFN-dependent mechanism. These results coincide with a muted responses in the bone marrow hematopoietic stem and progenitor cells (HSPCs) and progenitors following RDR Mtb infection. These results suggest that host directed therapeutics and vaccines for drug resistant TB may need to be target specific host immune pathways for protection.
Project description:Tuberculosis (TB) is one of the deadliest infectious disorders in the world. To effectively TB manage, an essential step is to gain insight into the lineage of Mycobacterium tuberculosis (MTB) strains and the distribution of drug resistance. Although the Campania region is declared a cluster area for the infection, to contribute to the effort to understand TB evolution and transmission, still poorly known, we have generated a dataset of 159 genomes of MTB strains, from Campania region collected during 2018-2021, obtained from the analysis of whole genome sequence data. The results show that the most frequent MTB lineage is the 4 according for 129 strains (81.11%). Regarding drug resistance, 139 strains (87.4%) were classified as multi susceptible, while the remaining 20 (12.58%) showed drug resistance. Among the drug-resistance strains, 8 were isoniazid-resistant MTB (HR-MTB), 7 were resistant only to one antibiotic (3 were resistant only to ethambutol and 3 isolate to streptomycin while one isolate showed resistance to fluoroquinolones), 4 multidrug-resistant MTB, while only one was classified as pre-extensively drug-resistant MTB (pre-XDR). This dataset expands the existing available knowledge on drug resistance and evolution of MTB, contributing to further TB-related genomics studies to improve the management of TB infection.
Project description:The identification of multidrug resistant (MDR), extensively and totally drug resistant Mycobacterium tuberculosis (Mtb), in vulnerable sites such as Mumbai, is a grave threat to the control of tuberculosis. The current study aimed at explaining the rapid expression of MDR in Directly Observed Treatment Short Course (DOTS) compliant patients, represents the first study comparing global transcriptional profiles of 3 pairs of clinical Mtb isolates, collected longitudinally at initiation and completion of DOTS. While the isolates were drug susceptible (DS) at onset and MDR at completion of DOTS, they exhibited identical DNA fingerprints at both points of collection. The whole genome transcriptional analysis was performed using total RNA from H37Rv and 3 locally predominant spoligotypes viz. MANU1, CAS and Beijing, hybridized on MTBv3 (BuG@S) microarray, and yielded 36, 98 and 45 differentially expressed genes respectively. Genes encoding transcription factors (sig, rpoB), cell wall biosynthesis (emb genes), protein synthesis (rpl) and additional central metabolic pathways (ppdK, pknH, pfkB) were found to be down regulated in the MDR isolates as compared to the DS isolate of the same genotype. Up regulation of drug efflux pumps, ABC transporters, trans-membrane proteins and stress response transcriptional factors (whiB) in the MDR isolates was observed. The data indicated that Mtb, without specific mutations in drug target genes may persist in the host due to additional mechanisms like drug efflux pumps and lowered rate of metabolism. Furthermore this population of Mtb, which also showed reduced DNA repair activity, would result in selection and stabilization of spontaneous mutations in drug target genes, causing selection of a MDR strain in the presence of drug pressures. Efflux pump such as drrA may play a significant role in increasing fitness of low level drug resistant cells and assist in survival of Mtb till acquisition of drug resistant mutations with least fitness cost. [Data is also available from http://bugs.sgul.ac.uk/E-BUGS-134]
Project description:Among the multidrug-resistant (MDR) clones of Mycobacterium tuberculosis (Mtb) that were epidemiologically particularly successful, the 100-32 MDR Beijing clone, also called B0/W148 clone, has emerged since the early sixties. These B0/W148 strains belonging to the lineage 2 within the global Mtb phylogeny, are the main contributors to the MDR epidemic in Russia and Eastern Europe, and since the USSR’s fall, have also propagated to Western Europe. Among the various mutations that were identified as being specific for the MDR B0/W148 clone, we focused on two found in the transcriptional regulators KdpDE and WhiB6 and characterized in a H37Rv strain background the transcriptional profile associated with these mutations and their potential impact on the in vitro and in vivo growth characteristics.
Project description:Among the multidrug-resistant (MDR) clones of Mycobacterium tuberculosis (Mtb) that were epidemiologically particularly successful, the 100-32 MDR Beijing clone, also called B0/W148 clone, has emerged since the early sixties. These B0/W148 strains belonging to the lineage 2 within the global Mtb phylogeny, are the main contributors to the MDR epidemic in Russia and Eastern Europe, and since the USSR’s fall, have also propagated to Western Europe. Among the various mutations that were identified as being specific for the MDR B0/W148 clone, we focused on two found in the transcriptional regulators KdpDE and WhiB6 and characterized in a H37Rv strain background the transcriptional profile associated with these mutations and their potential impact on the in vitro and in vivo growth characteristics.