scholarly journals Effect of Moxifloxacin plus Pretomanid against Mycobacterium tuberculosis in Log Phase, Acid Phase, and Nonreplicating-Persister Phase in an In Vitro Assay

2018 ◽  
Vol 63 (1) ◽  
Author(s):  
Carolina de Miranda Silva ◽  
Amirhossein Hajihosseini ◽  
Jenny Myrick ◽  
Jocelyn Nole ◽  
Arnold Louie ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Animal Studies ◽  
Screening Strategy ◽  
Infection Model ◽  
Logarithmic Growth Phase ◽  
Vitro Assay ◽  
Content Type ◽  
Successful Approach ◽  
Resistant Strains

ABSTRACT Combination therapy is a successful approach to treat tuberculosis in patients with susceptible strains of Mycobacterium tuberculosis. However, the emergence of resistant strains requires identification of new, effective therapies. Pretomanid (PA824) and moxifloxacin (MXF) are promising options currently under evaluation in clinical trials for the treatment of susceptible and resistant mycobacteria. We applied our recently described screening strategy to characterize the interaction between PA824 and MXF toward the killing of M. tuberculosis in logarithmic growth phase (log phase), acid phase, and nonreplicating-persister (NRP) phase. Respective in vitro data generated for the H37Rv and 18b strains were evaluated in a microdilution plate system containing both drugs in combination. The Universal Response Surface Approach model from Greco et al. (W. R. Greco, G. Bravo, and J. C. Parsons, Pharmacol Rev 47:331–385, 1995) was used to characterize the nature of the interaction between both drugs; synergistic or additive combinations would prompt additional evaluation in the hollow-fiber infection model (HFIM) and in animal studies. The interaction between MXF and PA824 was additive against M. tuberculosis organisms in acid phase (interaction parameter [α] = 5.56e−8 [95% confidence interval {CI} = −0.278 to 0.278] and α = 0.408 [95% CI = 0.105 to 0.711], respectively), NRP phase (α = 0.625 [95% CI = −0.556 to 1.81] and α = 2.92 [95% CI = 0.215 to 5.63], respectively), and log phase (α = 1.57e−6 [95% CI = −0.930 to 0.930] and α = 1.83e−6 [95% CI = −0.929 and 0.929], respectively), prompting further testing of this promising combination for the treatment of tuberculosis in the HFIM and in animal studies.

scholarly journals In Vitro Isolation and Characterization of Oxazolidinone-Resistant Mycobacterium tuberculosis

2017 ◽  
Vol 61 (10) ◽  
Author(s):  
Matthew B. McNeil ◽  
Devon D. Dennison ◽  
Catherine D. Shelton ◽  
Tanya Parish
Keyword(s):  
Mycobacterium Tuberculosis ◽  
23S Rrna ◽  
Clinical Settings ◽  
Content Type ◽  
Isolation And Characterization ◽  
Mutant Strains ◽  
Ribosomal Protein L3 ◽  
Resistant Strains

ABSTRACT Oxazolidinones are promising candidates for the treatment of Mycobacterium tuberculosis infections. We isolated linezolid-resistant strains from H37Rv (Euro-American) and HN878 (East-Asian) strains; resistance frequencies were similar in the two strains. Mutations were identified in ribosomal protein L3 (RplC) and the 23S rRNA (rrl). All mutant strains were cross resistant to sutezolid; a subset was cross resistant to chloramphenicol. Mutations in rrl led to growth impairment and decreased fitness that may limit spread in clinical settings.

scholarly journals In Vitro Activity and MIC of Sitafloxacin against Multidrug-Resistant and Extensively Drug-Resistant Mycobacterium tuberculosis Isolated in Thailand

2017 ◽  
Vol 62 (1) ◽  
Author(s):  
Manoon Leechawengwongs ◽  
Therdsak Prammananan ◽  
Sarinya Jaitrong ◽  
Pamaree Billamas ◽  
Nampueng Makhao ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Critical Concentration ◽  
Multidrug Resistant ◽  
Quinolone Resistance ◽  
Drug Resistant ◽  
Content Type ◽  
Extensively Drug Resistant ◽  
Resistant Strains ◽  
Drug Resistant Strains

ABSTRACT New fluoroquinolones (FQs) have been shown to be more active against drug-resistant Mycobacterium tuberculosis strains than early FQs, such as ofloxacin. Sitafloxacin (STFX) is a new fluoroquinolone with in vitro activity against a broad range of bacteria, including M. tuberculosis. This study aimed to determine the in vitro activity of STFX against all groups of drug-resistant strains, including multidrug-resistant M. tuberculosis (MDR M. tuberculosis), MDR M. tuberculosis with quinolone resistance (pre-XDR), and extensively drug-resistant (XDR) strains. A total of 374 drug-resistant M. tuberculosis strains were tested for drug susceptibility by the conventional proportion method, and 95 strains were randomly submitted for MIC determination using the microplate alamarBlue assay (MABA). The results revealed that all the drug-resistant strains were susceptible to STFX at a critical concentration of 2 μg/ml. Determination of the MIC90s of the strains showed different MIC levels; MDR M. tuberculosis strains had a MIC90 of 0.0625 μg/ml, whereas pre-XDR and XDR M. tuberculosis strains had identical MIC90s of 0.5 μg/ml. Common mutations within the quinolone resistance-determining region (QRDR) of gyrA and/or gyrB did not confer resistance to STFX, except that double mutations of GyrA at Ala90Val and Asp94Ala were found in strains with a MIC of 1.0 μg/ml. The results indicated that STFX had potent in vitro activity against all the groups of drug-resistant M. tuberculosis strains and should be considered a new repurposed drug for treatment of multidrug-resistant and extensively drug-resistant TB.

scholarly journals Importance of Confirming Data on theIn VivoEfficacy of Novel Antibacterial Drug Regimens against Various Strains of Mycobacterium tuberculosis

2011 ◽  
Vol 56 (2) ◽  
pp. 731-738 ◽  
Author(s):  
Mary A. De Groote ◽  
Veronica Gruppo ◽  
Lisa K. Woolhiser ◽  
Ian M. Orme ◽  
Janet C. Gilliland ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Animal Studies ◽  
Strain Difference ◽  
Drug Combinations ◽  
Antibacterial Drug ◽  
Preclinical Testing ◽  
Content Type ◽  
Drug Regimens

ABSTRACTIn preclinical testing of antituberculosis drugs, laboratory-adapted strains ofMycobacterium tuberculosisare usually used both forin vitroandin vivostudies. However, it is unknown whether the heterogeneity ofM. tuberculosisstocks used by various laboratories can result in different outcomes in tests of antituberculosis drug regimens in animal infection models. In head-to-head studies, we investigated whether bactericidal efficacy results in BALB/c mice infected by inhalation with the laboratory-adapted strains H37Rv and Erdman differ from each other and from those obtained with clinical tuberculosis strains. Treatment of mice consisted of dual and triple drug combinations of isoniazid (H), rifampin (R), and pyrazinamide (Z). The results showed that not all strains gave the samein vivoefficacy results for the drug combinations tested. Moreover, the ranking of HRZ and RZ efficacy results was not the same for the two H37Rv strains evaluated. The magnitude of this strain difference also varied between experiments, emphasizing the risk of drawing firm conclusions for human trials based on single animal studies. The results also confirmed that the antagonism seen within the standard HRZ regimen by some investigators appears to be anM. tuberculosisstrain-specific phenomenon. In conclusion, the specific identity ofM. tuberculosisstrain used was found to be an important variable that can change the apparent outcome ofin vivoefficacy studies in mice. We highly recommend confirmation of efficacy results in late preclinical testing against a differentM. tuberculosisstrain than the one used in the initial mouse efficacy study, thereby increasing confidence to advance potent drug regimens to clinical trials.

scholarly journals High-Content Screening Technology Combined with a Human Granuloma Model as a New Approach To Evaluate the Activities of Drugs against Mycobacterium tuberculosis

2014 ◽  
Vol 59 (1) ◽  
pp. 693-697 ◽  
Author(s):  
Mayra Silva-Miranda ◽  
Euloge Ekaza ◽  
Adrien Breiman ◽  
Karim Asehnoune ◽  
David Barros-Aguirre ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
High Content Screening ◽  
Drug Resistant ◽  
Major Health Problem ◽  
Major Health ◽  
New Approach ◽  
Content Type ◽  
Resistant Strains ◽  
Drug Resistant Strains

ABSTRACTTuberculosis remains a major health problem due to the emergence of drug-resistant strains ofMycobacterium tuberculosis. Some models have provided valuable information about drug resistance and efficacy; however, the translation of these results into effective human treatments has mostly proven unsuccessful. In this study, we adapted high-content screening (HCS) technology to investigate the activities of antitubercular compounds in the context of anin vitrogranuloma model. We observed significant shifts in the MIC50s between the activities of the compounds under extracellular and granuloma conditions.

scholarly journals Effect of Linezolid plus Bedaquiline againstMycobacterium tuberculosisin Log Phase, Acid Phase, and Nonreplicating-Persister Phase in anIn VitroAssay

2018 ◽  
Vol 62 (8) ◽  
Author(s):  
Carolina de Miranda Silva ◽  
Amirhossein Hajihosseini ◽  
Jenny Myrick ◽  
Jocelyn Nole ◽  
Arnold Louie ◽  
...  
Keyword(s):  
Treatment Success ◽  
Infection Model ◽  
Phase Growth ◽  
Bacterial Killing ◽  
Content Type ◽  
Metabolic States ◽  
Resistant Strains ◽  
Emergence Of Resistance

ABSTRACTTuberculosis is the ninth-leading cause of death worldwide. Treatment success is approximately 80% for susceptible strains and decreases to 30% for extensively resistant strains. Shortening the therapy duration forMycobacterium tuberculosisis a major goal, which can be attained with the use of combination therapy. However, the identification of the most promising combination is a challenge given the quantity of older and newer agents available. Our objective was to identify promising 2-drug combinations using anin vitrostrategy to ultimately be tested in anin vitrohollow fiber infection model (HFIM) and in animal models. We studied the effect of the combination of linezolid (LZD) and bedaquiline (BDQ) onM. tuberculosisstrain H37Rv in log- and acid-phase growth andM. tuberculosisstrain 18b in log- and nonreplicating-persister-phase growth in a plate system containing a 9-by-8 matrix of concentrations of both drugs alone and in combinations. A characterization of the interaction as antagonistic, additive, or synergistic was performed using the Greco universal response surface approach (URSA) model. Our results indicate that the interaction between LZD and BDQ is additive for bacterial killing in both strains for both of the metabolic states tested. This prescreen strategy was suitable to identify LZD and BDQ as a promising combination to be further tested in the HFIM. The presence of nonoverlapping mechanisms of drug action suggests each drug in the combination will likely be effective in suppressing the emergence of resistance byM. tuberculosisto the companion drug, which holds promise in improving treatment outcomes for tuberculosis.

scholarly journals In Vitro Efficacies, ADME, and Pharmacokinetic Properties of Phenoxazine Derivatives Active against Mycobacterium tuberculosis

2019 ◽  
Vol 63 (11) ◽  
Author(s):  
Lloyd Tanner ◽  
Joanna C. Evans ◽  
Ronnett Seldon ◽  
Audrey Jordaan ◽  
Digby F. Warner ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Infected Animal ◽  
Mechanisms Of Action ◽  
Drug Resistant ◽  
Content Type ◽  
Pharmacokinetic Properties ◽  
Resistant Strains ◽  
Drug Resistant Strains

ABSTRACT Mycobacterium tuberculosis, the causative agent of tuberculosis, remains a leading infectious killer globally, demanding the urgent development of faster-acting drugs with novel mechanisms of action. Riminophenazines such as clofazimine are clinically efficacious against both drug-susceptible and drug-resistant strains of M. tuberculosis. We determined the in vitro anti-M. tuberculosis activities, absorption, distribution, metabolism, and excretion properties, and in vivo mouse pharmacokinetics of a series of structurally related phenoxazines. One of these, PhX1, displayed promising drug-like properties and potent in vitro efficacy, supporting its further investigation in an M. tuberculosis-infected animal model.

scholarly journals Characterization of Mutations Conferring Resistance to Rifampin inMycobacterium tuberculosisClinical Strains

2018 ◽  
Vol 62 (10) ◽  
Author(s):  
Tomasz Jagielski ◽  
Zofia Bakuła ◽  
Anna Brzostek ◽  
Alina Minias ◽  
Radosław Stachowiak ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Content Type ◽  
Control Programs ◽  
Gene Coding ◽  
H37rv Strain ◽  
Different Types ◽  
Resistant Strains

ABSTRACTResistance ofMycobacterium tuberculosisto rifampin (RMP), mediated by mutations in therpoBgene coding for the beta-subunit of RNA polymerase, poses a serious threat to the efficacy of clinical management and, thus, control programs for tuberculosis (TB). The contribution of many individualrpoBmutations to the development and level of RMP resistance remains elusive. In this study, the incidence of mutations throughout therpoBgene among 115Mycobacterium tuberculosisclinical isolates, both resistant and susceptible to RMP, was determined. Of the newly discoveredrpoBmutations, the role of three substitutions in the causation of RMP resistance was empirically tested. The results fromin vitromutagenesis experiments were combined with the assessment of the prevalence ofrpoBmutations, and their reciprocal co-occurrences, across globalM. tuberculosispopulations. Twenty-two different types of mutations in therpoBgene were identified and distributed among 58 (89.2%) RMP-resistant strains. The MICs of RMP were within the range of 40 to 800 mg/liter, with MIC50and MIC90values of 400 and 800 mg/liter, respectively. None of the mutations (Gln429His, Met434Ile, and Arg827Cys) inspected for their role in the development of RMP resistance produced an RMP-resistant phenotype in isogenicM. tuberculosisH37Rv strain-derived mutants. These mutations are supposed to compensate for fitness impairment incurred by other mutations directly associated with drug resistance.

scholarly journals In Vitro Activity of Tedizolid against Mycobacterium tuberculosis

2019 ◽  
Vol 63 (4) ◽  
Author(s):  
Pilar Ruiz ◽  
Manuel Causse ◽  
Manuel Vaquero ◽  
Manuel Casal
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Multidrug Resistant ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
First Line ◽  
Gram Positive ◽  
Content Type ◽  
Resistant Strains

ABSTRACT Tedizolid is a novel oxazolidinone with activities against Gram-positive microorganisms, including mycobacteria. We studied the in vitro activity of tedizolid against 120 Mycobacterium tuberculosis strains, including susceptible, first-line-resistant, and multidrug-resistant isolates. MIC was tested using the Bactec 960 MGIT system. MIC90 and MIC50 were 0.5 and 0.25 μg/ml, respectively, in susceptible and resistant strains. Tedizolid may be an alternative in the treatment of resistant M. tuberculosis.

scholarly journals Higher Dosing of Rifamycins Does Not Increase Activity against Mycobacterium tuberculosis in the Hollow-Fiber Infection Model

2021 ◽  
Vol 65 (4) ◽  
Author(s):  
E. D. Pieterman ◽  
S. van den Berg ◽  
A. van der Meijden ◽  
E. M. Svensson ◽  
H. I. Bax ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Drug Development ◽  
Hollow Fiber ◽  
Standard Dose ◽  
Free Fraction ◽  
Infection Model ◽  
Preclinical Model ◽  
Content Type ◽  
Development Pipeline

ABSTRACT Improvements in the translational value of preclinical models can allow more-successful and more-focused research on shortening the duration of tuberculosis treatment. Although the hollow-fiber infection model (HFIM) is considered a valuable addition to the drug development pipeline, its exact role has not been fully determined yet. Since the strategy of increasing the dose of rifamycins is being evaluated for its treatment-shortening potential, additional in vitro modeling is important. Therefore, we assessed increased dosing of rifampin and rifapentine in our HFIM in order to gain more insight into the place of the HFIM in the drug development pipeline. Total and free-fraction concentrations corresponding to daily dosing of 2.7, 10, and 50 mg of rifampin/kg of body weight, as well as 600 mg and 1,500 mg rifapentine, were assessed in our HFIM using the Mycobacterium tuberculosis H37Rv strain. Drug activity and the emergence of drug resistance were assessed by CFU counting and subsequent mathematical modeling over 14 days, and pharmacokinetic exposures were checked. We found that increasing rifampin exposure above what is expected with the standard dose did not result in higher antimycobacterial activity. For rifapentine, only the highest concentration showed increased activity, but the clinical relevance of this observation is questionable. Moreover, for both drugs, the emergence of resistance was unrelated to exposure. In conclusion, in the simplest experimental setup, the results of the HFIM did not fully correspond to preexisting clinical data. The inclusion of additional parameters and readouts in this preclinical model could be of interest for proper assessment of the translational value of the HFIM.

scholarly journals Mutations in fbiD (Rv2983) as a Novel Determinant of Resistance to Pretomanid and Delamanid in Mycobacterium tuberculosis

2020 ◽  
Vol 65 (1) ◽  
pp. e01948-20
Author(s):  
Dalin Rifat ◽  
Si-Yang Li ◽  
Thomas Ioerger ◽  
Keshav Shah ◽  
Jean-Philippe Lanoix ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Clinical Evidence ◽  
Clinical Samples ◽  
Loss Of Function ◽  
Wild Type ◽  
Content Type ◽  
Solid Media ◽  
High Level ◽  
Level Resistance

ABSTRACTThe nitroimidazole prodrugs delamanid and pretomanid comprise one of only two new antimicrobial classes approved to treat tuberculosis (TB) in 50 years. Prior in vitro studies suggest a relatively low barrier to nitroimidazole resistance in Mycobacterium tuberculosis, but clinical evidence is limited to date. We selected pretomanid-resistant M. tuberculosis mutants in two mouse models of TB using a range of pretomanid doses. The frequency of spontaneous resistance was approximately 10−5 CFU. Whole-genome sequencing of 161 resistant isolates from 47 mice revealed 99 unique mutations, of which 91% occurred in 1 of 5 genes previously associated with nitroimidazole activation and resistance, namely, fbiC (56%), fbiA (15%), ddn (12%), fgd (4%), and fbiB (4%). Nearly all mutations were unique to a single mouse and not previously identified. The remaining 9% of resistant mutants harbored mutations in Rv2983 (fbiD), a gene not previously associated with nitroimidazole resistance but recently shown to be a guanylyltransferase necessary for cofactor F420 synthesis. Most mutants exhibited high-level resistance to pretomanid and delamanid, although Rv2983 and fbiB mutants exhibited high-level pretomanid resistance but relatively small changes in delamanid susceptibility. Complementing an Rv2983 mutant with wild-type Rv2983 restored susceptibility to pretomanid and delamanid. By quantifying intracellular F420 and its precursor Fo in overexpressing and loss-of-function mutants, we provide further evidence that Rv2983 is necessary for F420 biosynthesis. Finally, Rv2983 mutants and other F420H2-deficient mutants displayed hypersusceptibility to some antibiotics and to concentrations of malachite green found in solid media used to isolate and propagate mycobacteria from clinical samples.

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