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Mycobacterium tuberculosis AND drug use and [keywords]
- Rapid sequencing of the Mycobacterium tuberculosis pncA gene for the detection of pyrazinamide susceptibility. [JOURNAL ARTICLE]
- J Clin Microbiol 2014 Aug 27.
We developed a pyrazinamidase gene DNA sequencing method to rapidly identify pyrazinamide resistance causing mutations in GenoLyse® treated smear positive sputum specimens. The sensitivity and specificity was 90.9% and 100% respectively compared to MGIT drug susceptibility testing, after excluding synonymous mutations and non-synonymous mutations previously associated with susceptibility to pyrazinamide.
- Biological Evaluation of Potent Triclosan-Derived Inhibitors of the Enoyl-Acyl Carrier Protein Reductase InhA in Drug-Sensitive and Drug-Resistant Strains of Mycobacterium tuberculosis. [JOURNAL ARTICLE]
- ChemMedChem 2014 Aug 27.
New triclosan (TRC) analogues were evaluated for their activity against the enoyl-acyl carrier protein reductase InhA in Mycobacterium tuberculosis (Mtb). TRC is a well-known inhibitor of InhA, and specific modifications to its positions 5 and 4' afforded 27 derivatives; of these compounds, seven derivatives showed improved potency over that of TRC. These analogues were active against both drug-susceptible and drug-resistant Mtb strains. The most active compound in this series, 4-(n-butyl)-1,2,3-triazolyl TRC derivative 3, had an MIC value of 0.6 μg mL(-1) (1.5 μM) against wild-type Mtb. At a concentration equal to its MIC, this compound inhibited purified InhA by 98 %, and showed an IC50 value of 90 nM. Compound 3 and the 5-methylisoxazole-modified TRC 14 were able to inhibit the biosynthesis of mycolic acids. Furthermore, mc(2) 4914, an Mtb strain overexpressing inhA, was found to be less susceptible to compounds 3 and 14, supporting the notion that InhA is the likely molecular target of the TRC derivatives presented herein.
- Inhibition of Glutamine Synthetase: A Potential Drug Target in Mycobacterium tuberculosis. [REVIEW]
- Molecules 2014; 19(9):13161-13176.
Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis. Globally, tuberculosis is second only to AIDS in mortality and the disease is responsible for over 1.3 million deaths each year. The impractically long treatment schedules (generally 6-9 months) and unpleasant side effects of the current drugs often lead to poor patient compliance, which in turn has resulted in the emergence of multi-, extensively- and totally-drug resistant strains. The development of new classes of anti-tuberculosis drugs and new drug targets is of global importance, since attacking the bacterium using multiple strategies provides the best means to prevent resistance. This review presents an overview of the various strategies and compounds utilized to inhibit glutamine synthetase, a promising target for the development of drugs for TB therapy.
- Dissemination of multidrug-resistant tuberculosis in a patient with acute HIV infection. [JOURNAL ARTICLE]
- BMC Infect Dis 2014 Aug 26; 14(1):462.
Opportunistic infections are relatively rare in early human immunodeficiency virus infection, especially infection with Mycobacterium tuberculosis. Here, we report a patient who presented with acute human immunodeficiency virus and multidrug-resistant M. tuberculosis co-infections.A 27-year-old homosexual male was admitted for fever, cough, and hepatitis. At the time of admission, the p24 antigen was detected in his serum, indicating that he had an acute human immunodeficiency virus infection. He was also diagnosed with disseminated tuberculosis spreading to the lung and skin. Anti-tuberculosis medication had been started earlier with one-week intervals of highly active antiretroviral therapy. Despite prolonged anti-tuberculosis treatment, the patient developed tuberculous meningitis on the 50th day of admission. Multidrug-resistant tuberculosis was cultured from his sputum and cerebrospinal fluid. The patient was successfully treated with second line anti-tuberculosis medication and antiretroviral treatment.This is the first case of acute human immunodeficiency virus and multi drug-resistance tuberculosis co-infections. This case indicates that tuberculosis infection should be considered even in patients with acute human immunodeficiency virus infection.
- Structure-Guided Design of Thiazolidine Derivatives as Mycobacterium tuberculosis Pantothenate Synthetase Inhibitors. [JOURNAL ARTICLE]
- ChemMedChem 2014 Aug 22.
The pantothenate biosynthetic pathway is essential for the persistent growth and virulence of Mycobacterium tuberculosis (Mtb) and one of the enzymes in the pathway, pantothenate synthetase (PS, EC: 188.8.131.52), encoded by the panC gene, has become an appropriate target for new therapeutics to treat tuberculosis. Herein, we report nanomolar thiazolidine inhibitors of Mtb PS developed by a rational inhibitor design approach. The thiazolidine compounds were discovered by using energy-based pharmacophore modelling and subsequent in vitro screening, which resulted in compounds with a half maximal inhibitory concentration (IC50 ) value of (1.12±0.12) μM. These compounds were subsequently optimised by a combination of modelling and synthetic chemistry. Hit expansion of the lead by chemical synthesis led to an improved inhibitor with an IC50 value of 350 nM and an Mtb minimum inhibitory concentration (MIC) of 1.55 μM. Some of these compounds also showed good activity against dormant Mtb cells.
- Respiratory flexibility in response to inhibition of cytochrome C oxidase in Mycobacterium tuberculosis. [JOURNAL ARTICLE]
- Antimicrob Agents Chemother 2014 Aug 25.
We report here on a series of five chemically diverse scaffolds that have activity in vitro on both replicating and hypoxic non-replicating bacilli by targeting the respiratory bc1 complex in Mycobacterium tuberculosis, in a strain-dependent manner. Deletion of the cytochrome bd oxidase generated a hyper-susceptible mutant in which resistance was acquired by mutation in qcrB. These results highlight the promiscuity of the bc1 complex and highlight the risk of targeting energy metabolism with new drugs.
- Cationic amphipathic D-enantiomeric antimicrobial peptides with in vitro and ex vivo activity against drug-resistant Mycobacterium tuberculosis. [JOURNAL ARTICLE]
- Tuberculosis (Edinb) 2014 Aug 12.
Tuberculosis (TB) is the leading cause of bacterial death worldwide. Due to the emergence of multi-drug resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB), and the persistence of latent infections, a safe and effective TB therapy is highly sought after. Antimicrobial peptides (AMPs) have therapeutic potential against infectious diseases and have the ability to target microbial pathogens within eukaryotic cells. In the present study, we investigated the activity of a family of six AMPs containing all-D amino acids (D-LAK peptides) against MDR and XDR clinical strains of Mycobacterium tuberculosis (Mtb) both in vitro and, using THP-1 cells as a macrophage model, cultured ex vivo. All the D-LAK peptides successfully inhibited the growth of Mtb in vitro and were similarly effective against MDR and XDR strains. D-LAK peptides effectively broke down the heavy clumping of mycobacteria in broth culture, consistent with a 'detergent-like effect' that could reduce the hydrophobic interactions between the highly lipidic cell walls of the mycobacteria, preventing bacteria cell aggregation. Furthermore, though not able to eradicate the intracellular mycobacteria, D-LAK peptides substantially inhibited the intracellular growth of drug-resistant Mtb clinical isolates at concentrations that were well tolerated by THP-1 cells. Finally, combining D-LAK peptide with isoniazid could enhance the anti-TB efficacy. D-LAK peptide, particularly D-LAK120-A, was effective as an adjunct agent at non-toxic concentration to potentiate the efficacy of isoniazid against drug-resistant Mtb in vitro, possibly by facilitating the access of isoniazid into the mycobacteria by increasing the surface permeability of the pathogen.
- Effectiveness and tuberculosis-related safety profile of interleukin-1 blocking agents in the management of Behçet's disease. [REVIEW]
- Autoimmun Rev 2014 Aug 21.
Behçet's disease (BD) is a multi-systemic disorder of unknown etiology characterized by relapsing oral-genital ulcers, uveitis, and involvement of the articular, gastrointestinal, neurologic, and vascular systems. Although the primum movens of this condition remains unknown, a tangled plot combining autoimmune and autoinflammatory pathways has been hypothesized to explain its start and recurrence. In-depth analysis of BD pathogenetic mechanisms, involving dysfunction of multiple proinflammatory molecules, has opened new modalities of treatment: different agents targeting interleukin-1 have been studied in recent years to manage the most difficult and multi-resistant cases of BD. Growing experience with anakinra, canakimumab and gevokizumab is discussed in this review, highlighting the relative efficacy of each drug upon the protean BD clinical manifestations. Safety and tolerability of interleukin-1 antagonists in different doses have been confirmed by numerous observational studies on both large and small cohorts of patients with BD. In particular, the potential for Mycobacterium tuberculosis reactivation and tuberculosis development appears to be significantly lower with interleukin-1 blockers compared to tumor necrosis factor-α inhibitors, thus increasing the beneficial profile of this approach.
- Incorporation of triphenylphosphonium functionality improves the inhibitory properties of phenothiazine derivatives in Mycobacterium tuberculosis. [JOURNAL ARTICLE]
- Bioorg Med Chem 2014 Aug 7.
Tuberculosis (TB) is a difficult to treat disease caused by the bacterium Mycobacterium tuberculosis. The need for improved therapies is required to kill different M. tuberculosis populations present during infection and to kill drug resistant strains. Protein complexes associated with energy generation, required for the survival of all M. tuberculosis populations, have shown promise as targets for novel therapies (e.g., phenothiazines that target type II NADH dehydrogenase (NDH-2) in the electron transport chain). However, the low efficacy of these compounds and their off-target effects has made the development of phenothiazines as a therapeutic agent for TB limited. This study reports that a series of alkyltriphenylphosphonium (alkylTPP) cations, a known intracellular delivery functionality, improves the localization and effective concentration of phenothiazines at the mycobacterial membrane. AlkylTPP cations were shown to accumulate at biological membranes in a range of bacteria and lipophilicity was revealed as an important feature of the structure-function relationship. Incorporation of the alkylTPP cationic function significantly increased the concentration and potency of a series of phenothiazine derivatives at the mycobacterial membrane (the site of NDH-2), where the lead compound 3a showed inhibition of M. tuberculosis growth at 0.5μg/mL. Compound 3a was shown to act in a similar manner to that previously published for other active phenothiazines by targeting energetic processes (i.e., NADH oxidation and oxygen consumption), occurring in the mycobacterial membrane. This shows the enormous potential of alkylTPP cations to improve the delivery and therefore efficacy of bioactive agents targeting oxidative phosphorylation in the mycobacterial membrane.
- Temporal dynamics of Mycobacterium tuberculosis genotypes in New South Wales, Australia. [JOURNAL ARTICLE]
- BMC Infect Dis 2014 Aug 23; 14(1):455.
Molecular epidemiology of Mycobacterium tuberculosis, its transmission dynamics and population structure have become important determinants of targeted tuberculosis control programs. Here we describe recent changes in the distribution of M. tuberculosis genotypes in New South Wales (NSW), Australia and compared strain types with drug resistance, site of disease and demographic data.We evaluated all culture-confirmed newly identified tuberculosis cases in NSW, Australia, from 2010-2012. M. tuberculosis population structure and clustering rates were assessed using 24-loci Mycobacterial interspersed repetitive unit (MIRU) analysis and compared to MIRU data from 2006-2008.Of 1178 tuberculosis cases, 1128 (95.7%) were successfully typed. Beijing and East African Indian (EAI) lineage strains were most common (27.6% and 28.5%, respectively) with EAI strains increasing in relative abundance from 11.8% in 2006-2008 to 28.5% in 2010-2012. Few cases of multi-drug resistant tuberculosis were identified (18; 1.7%). Compared to 12-loci, 24-loci MIRU provided improved cluster resolution with 695 (61.6%) and 227 (20.1%) clustered cases identified, respectively. Detailed analysis of the largest cluster identified (an 11 member Beijing cluster) revealed wide geographic diversity in the absence of documented social contact.EAI strains of M. tuberculosis recently overtook Beijing family as a prevalent cause of tuberculosis in NSW, Australia. This lineage appeared to be less commonly related to multi-drug resistant tuberculosis as compared to Beijing strain lineage. The resolution provided by 24-loci MIRU typing was insufficient for reliable assessment of transmissions, especially of Beijing family strains.