RESUMO
SQ109 is a tuberculosis drug candidate that has high potency against Mycobacterium tuberculosis and is thought to function at least in part by blocking cell wall biosynthesis by inhibiting the MmpL3 transporter. It also has activity against bacteria and protozoan parasites that lack MmpL3, where it can act as an uncoupler, targeting lipid membranes and Ca2+ homeostasis. Here, we synthesized 18 analogs of SQ109 and tested them against M. smegmatis, M. tuberculosis, M. abscessus, Bacillus subtilis, and Escherichia coli, as well as against the protozoan parasites Trypanosoma brucei, T. cruzi, Leishmania donovani, L. mexicana, and Plasmodium falciparum. Activity against the mycobacteria was generally less than with SQ109 and was reduced by increasing the size of the alkyl adduct, but two analogs were â¼4-8-fold more active than SQ109 against M. abscessus, including a highly drug-resistant strain harboring an A309P mutation in MmpL3. There was also better activity than found with SQ109 with other bacteria and protozoa. Of particular interest, we found that the adamantyl C-2 ethyl, butyl, phenyl, and benzyl analogs had 4-10× increased activity against P. falciparum asexual blood stages, together with low toxicity to a human HepG2 cell line, making them of interest as new antimalarial drug leads. We also used surface plasmon resonance to investigate the binding of inhibitors to MmpL3 and differential scanning calorimetry to investigate binding to lipid membranes. There was no correlation between MmpL3 binding and M. tuberculosis or M. smegmatis cell activity, suggesting that MmpL3 is not a major target in mycobacteria. However, some of the more active species decreased lipid phase transition temperatures, indicating increased accumulation in membranes, which is expected to lead to enhanced uncoupler activity.
Assuntos
Malária , Mycobacterium abscessus , Mycobacterium tuberculosis , Parasitos , Tuberculose , Animais , Humanos , Antituberculosos/farmacologia , Parasitos/metabolismo , Proteínas de Bactérias/metabolismo , Tuberculose/microbiologia , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/metabolismo , LipídeosRESUMO
BACKGROUND: The turnaround times for phenotypic tests used to monitor the bacterial load of Mycobacterium tuberculosis, in both clinical and preclinical studies, are delayed by the organism's slow growth in culture media. The existence of differentially culturable populations of M.tuberculosis may result in an underestimate of the true number. Moreover, culture methods are susceptible to contamination resulting in loss of critical data points. OBJECTIVES: We report the adaptation of our robust, culture-free assay utilising 16S ribosomal RNA, developed for sputum, to enumerate the number of bacteria present in animal tissues as a tool to improve the read-outs in preclinical drug efficacy studies. METHODS: Initial assay adaptation was performed using naïve mouse lungs spiked with known quantities of M. tuberculosis and an internal RNA control. Tissues were homogenised, total RNA extracted, and enumeration performed using RT-qPCR. We then evaluated the utility of the assay, in comparison to bacterial counts estimated using growth assays on solid and liquid media, to accurately inform bacterial load in tissues from M. tuberculosis-infected mice before and during treatment with a panel of drug combinations. RESULTS: When tested on lung tissues derived from infected mice, the MBL assay produced comparable results to the bacterial counts in solid culture (colony forming units: CFU). Notably, under specific drug treatments, the MBL assay was able to detect a significantly higher number of M. tuberculosis compared to CFU, likely indicating the presence of bacteria that were unable to produce colonies in solid-based culture. Additionally, growth recovery in liquid media using the most probable number (MPN) assay was able to account for the discrepancy between the MBL assay and CFU number, suggesting that the MBL assay detects differentially culturable sub-populations of M. tuberculosis. CONCLUSIONS: The MBL assay can enumerate the bacterial load in animal tissues in real time without the need to wait for extended periods for cultures to grow. The readout correlates well with CFUs. Importantly, we have shown that the MBL is able to measure specific populations of bacteria not cultured on solid agar. The adaptation of this assay for preclinical studies has the potential to decrease the readout time of data acquisition from animal experiments and could represent a valuable tool for tuberculosis drug discovery and development.
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Infections caused by nontuberculous mycobacteria (NTM) are increasing worldwide, resulting in a new global health concern. NTM treatment is complex and requires combinations of several drugs for lengthy periods. In spite of this, NTM disease is often associated with poor treatment outcomes. The anti-parasitic family of macrocyclic lactones (ML) (divided in two subfamilies: avermectins and milbemycins) was previously described as having activity against mycobacteria, including Mycobacterium tuberculosis, Mycobacterium ulcerans, and Mycobacterium marinum, among others. Here, we aimed to characterize the in vitro anti-mycobacterial activity of ML against a wide range of NTM species, including Mycobacteroides abscessus. For this, Minimum Inhibitory Concentration (MIC) values of eight ML were determined against 80 strains belonging to nine different NTM species. Macrocyclic lactones showed variable ranges of anti-mycobacterial activity that were compound and species-dependent. Milbemycin oxime was the most active compound, displaying broad-spectrum activity with MIC lower than 8 mg/L. Time kill assays confirmed MIC data and showed bactericidal and sterilizing activity of some compounds. Macrocyclic lactones are available in many formulations and have been extensively used in veterinary and human medicine with suitable pharmacokinetics and safety properties. This information could be exploited to explore repurposing of anti-helminthics for NTM therapy.
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Antibiotic resistance is now a major threat to human health, and one approach to combating this threat is to develop resistance-resistant antibiotics. Synthetic antimicrobial polymers are generally resistance resistant, having good activity with low resistance rates but usually with low therapeutic indices. Here, we report our solution to this problem by introducing dual-selective mechanisms of action to a short amidine-rich polymer, which can simultaneously disrupt bacterial membranes and bind to bacterial DNA. The oligoamidine shows unobservable resistance generation but high therapeutic indices against many bacterial types, such as ESKAPE strains and clinical isolates resistant to multiple drugs, including colistin. The oligomer exhibited excellent effectiveness in various model systems, killing extracellular or intracellular bacteria in the presence of mammalian cells, removing all bacteria from Caenorhabditis elegans, and rescuing mice with severe infections. This "dual mechanisms of action" approach may be a general strategy for future development of antimicrobial polymers.
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Mycobacterium abscessus (Mab) is an emerging, nontuberculosis mycobacterium (NTM) that infects humans. Mab has two morphotypes, smooth (S) and rough (R), related to the production of glycopeptidolipid (GPL), that differ in pathogenesis. To further understand the pathogenicity of these morphotypes in vivo, the amphibian Xenopus laevis was used as an alternative animal model. Mab infections have been previously modeled in zebrafish embryos and mice, but Mab are cleared early from immunocompetent mice, preventing the study of chronic infection, and the zebrafish model cannot be used to model a pulmonary infection and T cell involvement. Here, we show that X. laevis tadpoles, which have lungs and T cells, can be used as a complementary model for persistent Mab infection and pathogenesis. Intraperitoneal (IP) inoculation of S and R Mab morphotypes disseminated to tadpole tissues including liver and lungs, persisting for up to 40 days without significant mortality. Furthermore, the R morphotype was more persistent, maintaining a higher bacterial load at 40 days postinoculation. In contrast, the intracardiac (IC) inoculation with S Mab induced significantly greater mortality than inoculation with the R Mab form. These data suggest that X. laevis tadpoles can serve as a useful comparative experimental organism to investigate pathogenesis and host resistance to M. abscessus.
Assuntos
Modelos Animais de Doenças , Mycobacterium abscessus/metabolismo , Xenopus laevis/crescimento & desenvolvimento , Animais , Resistência à Doença/imunologia , Interações Hospedeiro-Patógeno , Humanos , Larva/crescimento & desenvolvimento , Larva/imunologia , Larva/microbiologia , Fígado/imunologia , Fígado/microbiologia , Pulmão/imunologia , Pulmão/microbiologia , Camundongos Endogâmicos C57BL , Infecções por Mycobacterium não Tuberculosas/genética , Infecções por Mycobacterium não Tuberculosas/microbiologia , Mycobacterium abscessus/classificação , Mycobacterium abscessus/patogenicidade , Linfócitos T/imunologia , Linfócitos T/microbiologia , Fatores de Tempo , Virulência , Xenopus laevis/imunologia , Xenopus laevis/microbiologiaRESUMO
The folate biosynthetic pathway offers many druggable targets that have yet to be exploited in tuberculosis therapy. Herein, we have identified a series of small molecules that interrupt Mycobacterium tuberculosis (Mtb) folate metabolism by dual targeting of dihydrofolate reductase (DHFR), a key enzyme in the folate pathway, and its functional analog, Rv2671. We have also compared the antifolate activity of these compounds with that of para-aminosalicylic acid (PAS). We found that the bioactive metabolite of PAS, in addition to previously reported activity against DHFR, inhibits flavin-dependent thymidylate synthase in Mtb, suggesting a multi-targeted mechanism of action for this drug. Finally, we have shown that antifolate treatment in Mtb decreases the production of mycolic acids, most likely due to perturbation of the activated methyl cycle. We conclude that multi-targeting of the folate pathway in Mtb is associated with highly potent anti-mycobacterial activity.
Assuntos
Ácido 4-Aminobenzoico/farmacologia , Antituberculosos/farmacologia , Ácido Fólico/metabolismo , Mycobacterium tuberculosis/química , Bibliotecas de Moléculas Pequenas/farmacologia , Ácido 4-Aminobenzoico/química , Ácido 4-Aminobenzoico/metabolismo , Antituberculosos/química , Antituberculosos/metabolismo , Testes de Sensibilidade Microbiana , Estrutura Molecular , Mycobacterium tuberculosis/metabolismo , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/metabolismo , Tetra-Hidrofolato Desidrogenase/metabolismoRESUMO
The in vitro activity of omadacycline, a new tetracycline derivative, was evaluated against isolates of Mycobacterium abscessus, Mycobacterium chelonae, and Mycobacterium fortuitum using a broth microtiter dilution assay. Omadacycline had MIC90 values of 2 µg/ml, 0.25 µg/ml, and 0.5 µg/ml, respectively. The in vitro activity of omadacycline against rapidly growing mycobacteria indicates that it may have the potential to improve therapy for infections caused by these organisms.
Assuntos
Antibacterianos/farmacologia , Mycobacterium/efeitos dos fármacos , Tetraciclinas/farmacologia , Testes de Sensibilidade Microbiana , Mycobacterium abscessus/efeitos dos fármacos , Mycobacterium chelonae/efeitos dos fármacos , Mycobacterium fortuitum/efeitos dos fármacosAssuntos
Infecções por Mycobacterium não Tuberculosas/tratamento farmacológico , Micobactérias não Tuberculosas , Pesquisa Translacional Biomédica , Antibacterianos/uso terapêutico , Farmacorresistência Bacteriana , Interações Hospedeiro-Patógeno , Humanos , Infecções por Mycobacterium não Tuberculosas/diagnóstico , Infecções por Mycobacterium não Tuberculosas/prevenção & controle , Pesquisa Translacional Biomédica/métodosRESUMO
This Editorial discusses the state of research on drug resistance in the fields of cancer, infectious disease, and agriculture. Reaching across the aisle for a more cross-collaborative approach may lead to exciting breakthroughs toward tackling the challenges of drug resistance in each field.
Assuntos
Resistência Microbiana a Medicamentos , Resistencia a Medicamentos Antineoplásicos , Neoplasias/tratamento farmacológico , Agricultura , Doenças Transmissíveis/tratamento farmacológico , Humanos , Comunicação Interdisciplinar , Mutação , Processos EstocásticosRESUMO
The current standard of care therapy for pulmonary Mycobacterium kansasii infection is isoniazid (300 mg/day), rifampin (600 mg/day), and ethambutol (15 mg/kg/day) for 12 months after achieving sputum culture negativity. Rifampin is the key drug in this regimen. The contribution of isoniazid is unclear since its in vitro MICs against M. kansasii are near the peak achievable serum levels and more than 100-fold greater than the MICs for Mycobacterium tuberculosis. Ethambutol likely decreases the emergence of rifampin resistant organisms. There are several new drug classes (e.g., quinolones, macrolides, nitroimidazoles, diarylquinolines, and clofazimine) that exhibit antimycobacterial activities against M. tuberculosis but have not yet been adequately studied against M. kansasii infections. The evaluation of in vitro activities of these agents as well as their study in new regimens in comparison to the standard of care regimen in mouse infection models should be undertaken. This knowledge will inform development of human clinical trials of new regimens in comparison to the current standard of care regimen. It is likely that shorter and more effective therapy is achievable with currently available drugs.
Assuntos
Síndrome da Imunodeficiência Adquirida/tratamento farmacológico , Fármacos Anti-HIV/uso terapêutico , HIV-1/efeitos dos fármacos , Modelos Biológicos , Linfócitos T CD4-Positivos/virologia , Interações Medicamentosas , Humanos , Adesão à Medicação , Resultado do Tratamento , Viremia/tratamento farmacológicoRESUMO
The in vitro activity of contezolid (MRX-I) against clinical isolates of Mycobacterium tuberculosis was evaluated using a microtiter broth dilution assay. MRX-I was as effective as linezolid (LZD) in vitro MRX-I and LZD were subsequently studied in BALB/c mice infected intranasally with M. tuberculosis Erdman. MRX-I and LZD at 100 mg/kg significantly reduced the bacterial load in lungs compared to the untreated early and late controls.
Assuntos
Antituberculosos/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Oxazolidinonas/farmacologia , Piridonas/farmacologia , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Animais , Carga Bacteriana/efeitos dos fármacos , Modelos Animais de Doenças , Esquema de Medicação , Feminino , Humanos , Isoniazida/farmacologia , Linezolida/farmacologia , Pulmão/efeitos dos fármacos , Pulmão/microbiologia , Camundongos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Mycobacterium tuberculosis/crescimento & desenvolvimento , Mycobacterium tuberculosis/isolamento & purificação , Tetrazóis/farmacologia , Tuberculose Resistente a Múltiplos Medicamentos/microbiologiaRESUMO
To develop agents for the treatment of infections caused by Mycobacterium tuberculosis, a novel phenotypic screen was undertaken that identified a series of 2-N-aryl thiazole-based inhibitors of intracellular Mycobacterium tuberculosis. Analogs were optimized to improve potency against an attenuated BSL2 H37Ra laboratory strain cultivated in human macrophage cells in vitro. The insertion of a carboxylic acid functionality resulted in compounds that retained potency and greatly improved microsomal stability. However, the strong potency trends we observed in the attenuated H37Ra strain were inconsistent with the potency observed for virulent strains in vitro and in vivo.
Assuntos
Antibacterianos/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Tiazóis/farmacologia , Animais , Antibacterianos/síntese química , Antibacterianos/química , Relação Dose-Resposta a Droga , Humanos , Macrófagos/efeitos dos fármacos , Macrófagos/microbiologia , Camundongos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Relação Estrutura-Atividade , Tiazóis/síntese química , Tiazóis/químicaRESUMO
There is an urgent need for new antifungal compounds to treat various types of fungal infections, including pulmonary infections. This study was designed to investigate the potency of a novel compound (Mul-1867) against Candida spp. and Aspergillus spp. isolated from patients with fungal pneumonia, cystic fibrosis and chronic obstructive pulmonary disease. Mul-1867 was highly effective against susceptible control strains as well as resistant clinical isolates, with minimum fungicidal concentrations (MFCs) varying from 0.06 µg/mL to 0.5 µg/mL. It was also highly effective against pre-formed 48-h-old biofilms formed by yeasts and moulds. The half-minimal biofilm eradication concentration (MBEC50) was equal to the MFC. The minimum biofilm eradication concentration to eliminate 90% of biofilms (MBEC90) varied from 1 × to 4 × MFC. Scanning electron microscopy revealed morphological changes accompanied by the release of intracellular material from the fungal cells following exposure to Mul-1867. Furthermore, an increased concentration of nucleic acids was found in the medium after 5 min and 20 min of Mul-1867 treatment, indicating leakage of cytoplasmic contents. Overall, these data indicate that Mul-1867 may be a promising inhaled antifungal agent for the treatment and prevention of fungal respiratory infections.
Assuntos
Antifúngicos/farmacologia , Aspergillus/efeitos dos fármacos , Candida/efeitos dos fármacos , Aspergilose/microbiologia , Aspergillus/isolamento & purificação , Aspergillus/fisiologia , Biofilmes/efeitos dos fármacos , Candida/isolamento & purificação , Candida/fisiologia , Candidíase/microbiologia , Meios de Cultura/química , DNA Fúngico/análise , Humanos , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Microscopia Eletrônica de VarreduraRESUMO
Mycobacterium tuberculosis continues to cause widespread, life-threatening disease. In the last decade, this threat has grown dramatically as multi- and extensively-drug resistant (MDR and XDR) bacteria have spread globally and the number of agents that effectively treat these infections is significantly reduced. We have been developing the propargyl-linked antifolates (PLAs) as potent inhibitors of the essential enzyme dihydrofolate reductase (DHFR) from bacteria and recently found that charged PLAs with partial zwitterionic character showed improved mycobacterial cell permeability. Building on a hypothesis that these PLAs may penetrate the outer membrane of M. tuberculosis and inhibit the essential cytoplasmic DHFR, we screened a group of PLAs for antitubercular activity. In this work, we identified several PLAs as potent inhibitors of the growth of M. tuberculosis with several of the compounds exhibiting minimum inhibition concentrations equal to or less than 1 µg/mL. Furthermore, two of the compounds were very potent inhibitors of MDR and XDR strains. A high resolution crystal structure of one PLA bound to DHFR from M. tuberculosis reveals the interactions of the ligands with the target enzyme.
Assuntos
Antituberculosos/química , Proteínas de Bactérias , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Antagonistas do Ácido Fólico/química , Mycobacterium tuberculosis/enzimologia , Tetra-Hidrofolato Desidrogenase/metabolismo , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/metabolismo , HumanosRESUMO
There is a growing need for new antibiotics. Compounds that target the proton motive force (PMF), uncouplers, represent one possible class of compounds that might be developed because they are already used to treat parasitic infections, and there is interest in their use for the treatment of other diseases, such as diabetes. Here, we tested a series of compounds, most with known antiinfective activity, for uncoupler activity. Many cationic amphiphiles tested positive, and some targeted isoprenoid biosynthesis or affected lipid bilayer structure. As an example, we found that clomiphene, a recently discovered undecaprenyl diphosphate synthase inhibitor active against Staphylococcus aureus, is an uncoupler. Using in silico screening, we then found that the anti-glioblastoma multiforme drug lead vacquinol is an inhibitor of Mycobacterium tuberculosis tuberculosinyl adenosine synthase, as well as being an uncoupler. Because vacquinol is also an inhibitor of M. tuberculosis cell growth, we used similarity searches based on the vacquinol structure, finding analogs with potent (â¼0.5-2 µg/mL) activity against M. tuberculosis and S. aureus. Our results give a logical explanation of the observation that most new tuberculosis drug leads discovered by phenotypic screens and genome sequencing are highly lipophilic (logP â¼5.7) bases with membrane targets because such species are expected to partition into hydrophobic membranes, inhibiting membrane proteins, in addition to collapsing the PMF. This multiple targeting is expected to be of importance in overcoming the development of drug resistance because targeting membrane physical properties is expected to be less susceptible to the development of resistance.
Assuntos
Anti-Infecciosos/farmacologia , Força Próton-Motriz/efeitos dos fármacos , Desacopladores/farmacologia , Alquil e Aril Transferases/antagonistas & inibidores , Anti-Infecciosos/química , Fenômenos Biofísicos , Clomifeno/farmacologia , Descoberta de Drogas , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Humanos , Modelos Moleculares , Simulação de Dinâmica Molecular , Estrutura Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/enzimologia , Mycobacterium tuberculosis/crescimento & desenvolvimento , Piperidinas/farmacologia , Quinolinas/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/enzimologia , Desacopladores/químicaRESUMO
We synthesized a library of 48 analogs of the Mycobacterium tuberculosis cell growth inhibitor SQ109 in which the ethylene diamine linker was replaced by oxa-, thia- or heterocyclic species, and in some cases, the adamantyl group was replaced by a 1,2-carborane or the N-geranyl group by another hydrophobic species. Compounds were tested against Mycobacterium tuberculosis (H37Rv and/or Erdman), Mycobacterium smegmatis, Bacillus subtilis, Escherichia coli, Saccharomyces cerevisiae, Trypanosoma brucei and two human cell lines (human embryonic kidney, HEK293T, and the hepatocellular carcinoma, HepG2). Most potent activity was found against T. brucei, the causative agent of human African trypanosomiasis, and involved targeting of the mitochondrial membrane potential with 15 SQ109 analogs being more active than was SQ109 in cell growth inhibition, having IC50 values as low as 12 nM (5.5 ng/mL) and a selectivity index of ~300.
RESUMO
The minimal inhibitory concentrations (MICs) of copper and cobalt based dimeric pyrophosphate complexes with capping 1,10-phenanthroline groups on clinical isolates of C. albicans (28 isolates), C. krusei (20 isolates) and C. tropicalis (20 isolates) are reported. C. albicans was inhibited by the cobalt complex better than by the copper complex, while C. krusei demonstrated the opposite results. C. tropicalis showed similar sensitivities to both metals in terms of calculated MIC50 values but was more sensitive to cobalt when MIC90 values were noted. Knockout strains of C. albicans that had the copper efflux protein P-type ATPase (CRP1), the copper binding metallothionein CUP1 or both CRP1/CUP1 removed clearly demonstrate that the origins of copper resistant in C. albicans lies primarily in the P-type ATPase, with the MT playing an important secondary role in the absence of the efflux protein. This study suggests that certain strains of Candida have evolved to protect against particular metal ions and that in the case of C. albicans, a primary invasive fungal species, cobalt may be a good starting-point for new therapeutic development.
Assuntos
Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Candida tropicalis/efeitos dos fármacos , Complexos de Coordenação/farmacologia , Fenantrolinas/farmacologia , Transportadores de Cassetes de Ligação de ATP/genética , Antifúngicos/química , Candida albicans/fisiologia , Candida tropicalis/fisiologia , Cobalto/química , Complexos de Coordenação/química , Cobre/química , Farmacorresistência Fúngica , Técnicas de Inativação de Genes , Testes de Sensibilidade Microbiana , Fenantrolinas/químicaRESUMO
New drugs to treat drug-resistant tuberculosis are urgently needed. Extensively drug-resistant and probably the totally drug-resistant tuberculosis strains are resistant to fluoroquinolones like moxifloxacin, which target gyrase A, and most people infected with these strains die within a year. In this study, we found that a novel aminobenzimidazole, VXc-486, which targets gyrase B, potently inhibits multiple drug-sensitive isolates and drug-resistant isolates of Mycobacterium tuberculosis in vitro (MICs of 0.03 to 0.30 µg/ml and 0.08 to 5.48 µg/ml, respectively) and reduces mycobacterial burdens in lungs of infected mice in vivo. VXc-486 is active against drug-resistant isolates, has bactericidal activity, and kills intracellular and dormant M. tuberculosis bacteria in a low-oxygen environment. Furthermore, we found that VXc-486 inhibits the growth of multiple strains of Mycobacterium abscessus, Mycobacterium avium complex, and Mycobacterium kansasii (MICs of 0.1 to 2.0 µg/ml), as well as that of several strains of Nocardia spp. (MICs of 0.1 to 1.0 µg/ml). We made a direct comparison of the parent compound VXc-486 and a phosphate prodrug of VXc-486 and showed that the prodrug of VXc-486 had more potent killing of M. tuberculosis than did VXc-486 in vivo. In combination with other antimycobacterial drugs, the prodrug of VXc-486 sterilized M. tuberculosis infection when combined with rifapentine-pyrazinamide and bedaquiline-pyrazinamide in a relapse infection study in mice. Furthermore, the prodrug of VXc-486 appeared to perform at least as well as the gyrase A inhibitor moxifloxacin. These findings warrant further development of the prodrug of VXc-486 for the treatment of tuberculosis and nontuberculosis mycobacterial infections.
Assuntos
Antibacterianos/uso terapêutico , Benzimidazóis/uso terapêutico , Infecções por Mycobacterium/tratamento farmacológico , Inibidores da Topoisomerase II/uso terapêutico , Animais , Feminino , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Testes de Sensibilidade MicrobianaRESUMO
Previous studies indicated that inhibition of efflux pumps augments tuberculosis therapy. In this study, we used timcodar (formerly VX-853) to determine if this efflux pump inhibitor could increase the potency of antituberculosis (anti-TB) drugs against Mycobacterium tuberculosis in in vitro and in vivo combination studies. When used alone, timcodar weakly inhibited M. tuberculosis growth in broth culture (MIC, 19 µg/ml); however, it demonstrated synergism in drug combination studies with rifampin, bedaquiline, and clofazimine but not with other anti-TB agents. When M. tuberculosis was cultured in host macrophage cells, timcodar had about a 10-fold increase (50% inhibitory concentration, 1.9 µg/ml) in the growth inhibition of M. tuberculosis and demonstrated synergy with rifampin, moxifloxacin, and bedaquiline. In a mouse model of tuberculosis lung infection, timcodar potentiated the efficacies of rifampin and isoniazid, conferring 1.0 and 0.4 log10 reductions in bacterial burden in lung, respectively, compared to the efficacy of each drug alone. Furthermore, timcodar reduced the likelihood of a relapse infection when evaluated in a mouse model of long-term, chronic infection with treatment with a combination of rifampin, isoniazid, and timcodar. Although timcodar had no effect on the pharmacokinetics of rifampin in plasma and lung, it did increase the plasma exposure of bedaquiline. These data suggest that the antimycobacterial drug-potentiating activity of timcodar is complex and drug dependent and involves both bacterial and host-targeted mechanisms. Further study of the improvement of the potency of antimycobacterial drugs and drug candidates when used in combination with timcodar is warranted.