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Clinical Infectious Diseases : An... Mar 2020The relationships between first-line drug concentrations and clinically important outcomes among patients with tuberculosis (TB) remain poorly understood.
BACKGROUND
The relationships between first-line drug concentrations and clinically important outcomes among patients with tuberculosis (TB) remain poorly understood.
METHODS
We enrolled a prospective cohort of patients with new pulmonary TB receiving thrice-weekly treatment in India. The maximum plasma concentration of each drug was determined at months 1 and 5 using blood samples drawn 2 hours postdose. Subtherapeutic cutoffs were: rifampicin <8 µg/mL, isoniazid <3 µg/mL, and pyrazinamide <20 µg/mL. Factors associated with lower log-transformed drug concentrations, unfavorable outcomes (composite of treatment failure, all-cause mortality, and recurrence), and individual outcomes were examined using Poisson regression models.
RESULTS
Among 404 participants, rifampicin, isoniazid, and pyrazinamide concentrations were subtherapeutic in 85%, 29%, and 13%, respectively, at month 1 (with similar results for rifampicin and isoniazid at month 5). Rifampicin concentrations were lower with human immunodeficiency virus coinfection (median, 1.6 vs 4.6 µg/mL; P = .015). Unfavorable outcome was observed in 19%; a 1-μg/mL decrease in rifampicin concentration was independently associated with unfavorable outcome (adjusted incidence rate ratio [aIRR], 1.21 [95% confidence interval {CI}, 1.01-1.47]) and treatment failure (aIRR, 1.16 [95% CI, 1.05-1.28]). A 1-μg/mL decrease in pyrazinamide concentration was associated with recurrence (aIRR, 1.05 [95% CI, 1.01-1.11]).
CONCLUSIONS
Rifampicin concentrations were subtherapeutic in most Indian patients taking a thrice-weekly TB regimen, and low rifampicin and pyrazinamide concentrations were associated with poor outcomes. Higher or more frequent dosing is needed to improve TB treatment outcomes in India.
Topics: Antitubercular Agents; Humans; India; Isoniazid; Prospective Studies; Pyrazinamide; Rifampin; Treatment Outcome; Tuberculosis
PubMed: 31075166
DOI: 10.1093/cid/ciz380 -
Molecules (Basel, Switzerland) Mar 2020According to the World Health Organization, tuberculosis is still in the top ten causes of death from a single infectious agent, killing more than 1.7 million people...
According to the World Health Organization, tuberculosis is still in the top ten causes of death from a single infectious agent, killing more than 1.7 million people worldwide each year. The rising resistance developed by against currently used antituberculars is an imperative to develop new compounds with potential antimycobacterial activity. As a part of our continuous research on structural derivatives of the first-line antitubercular pyrazinamide, we have designed, prepared, and assessed the in vitro whole cell growth inhibition activity of forty-two novel 5-alkylamino--phenylpyrazine-2-carboxamides with various length of the alkylamino chain (propylamino to octylamino) and various simple substituents on the benzene ring. Final compounds were tested against H37Ra and four other mycobacterial strains (, , , ) in a modified Microplate Alamar Blue Assay. We identified several candidate molecules with micromolar MIC against H37Ra and low in vitro cytotoxicity in HepG2 cell line, for example, -(4-hydroxyphenyl)-5-(pentylamino)pyrazine-2-carboxamide (, MIC = 3.91 µg/mL or 13.02 µM, SI > 38) and 5-(heptylamino)--(-tolyl)pyrazine-2-carboxamide (, MIC = 0.78 µg/mL or 2.39 µM, SI > 20). In a complementary screening, we evaluated the in vitro activity against bacterial and fungal strains of clinical importance. We observed no antibacterial activity and sporadic antifungal activity against the genus.
Topics: Antitubercular Agents; Drug Design; Drug Development; Humans; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Pyrazinamide; Pyrazines; Structure-Activity Relationship
PubMed: 32231166
DOI: 10.3390/molecules25071561 -
CPT: Pharmacometrics & Systems... Nov 2021Tuberculosis (TB) remains a global health problem and there is an ongoing effort to develop more effective therapies and new combination regimes that can reduce duration... (Review)
Review
Tuberculosis (TB) remains a global health problem and there is an ongoing effort to develop more effective therapies and new combination regimes that can reduce duration of treatment. The purpose of this study was to demonstrate utility of a physiologically-based pharmacokinetic modeling approach to predict plasma and lung concentrations of 11 compounds used or under development as TB therapies (bedaquiline [and N-desmethyl bedaquiline], clofazimine, cycloserine, ethambutol, ethionamide, isoniazid, kanamycin, linezolid, pyrazinamide, rifampicin, and rifapentine). Model accuracy was assessed by comparison of simulated plasma pharmacokinetic parameters with healthy volunteer data for compounds administered alone or in combination. Eighty-four percent (area under the curve [AUC]) and 91% (maximum concentration [C ]) of simulated mean values were within 1.5-fold of the observed data and the simulated drug-drug interaction ratios were within 1.5-fold (AUC) and twofold (C ) of the observed data for nine (AUC) and eight (C ) of the 10 cases. Following satisfactory recovery of plasma concentrations in healthy volunteers, model accuracy was assessed further (where patients' with TB data were available) by comparing clinical data with simulated lung concentrations (9 compounds) and simulated lung: plasma concentration ratios (7 compounds). The 5th-95th percentiles for the simulated lung concentration data recovered between 13% (isoniazid and pyrazinamide) and 88% (pyrazinamide) of the observed data points (Am J Respir Crit Care Med, 198, 2018, 1208; Nat Med, 21, 2015, 1223; PLoS Med, 16, 2019, e1002773). The impact of uncertain model parameters, such as the fraction of drug unbound in lung tissue mass (fu ), is discussed. Additionally, the variability associated with the patient lung concentration data, which was sparse and included extensive within-subject, interlaboratory, and experimental variability (as well interindividual variability) is reviewed. All presented models are transparently documented and are available as open-source to aid further research.
Topics: Antitubercular Agents; Humans; Isoniazid; Pyrazinamide; Standard of Care; Tuberculosis
PubMed: 34623770
DOI: 10.1002/psp4.12707 -
Emerging Microbes & Infections Dec 2023In preclinical studies, a new antituberculosis drug regimen markedly reduced the time required to achieve relapse-free cure. This study aimed to preliminarily evaluate... (Randomized Controlled Trial)
Randomized Controlled Trial
In preclinical studies, a new antituberculosis drug regimen markedly reduced the time required to achieve relapse-free cure. This study aimed to preliminarily evaluate the efficacy and safety of this four-month regimen, consisting of clofazimine, prothionamide, pyrazinamide and ethambutol, with a standard six-month regimen in patients with drug-susceptible tuberculosis. An open-label pilot randomized clinical trial was conducted among the patients with newly diagnosed bacteriologically-confirmed pulmonary tuberculosis. The primary efficacy end-point was sputum culture negative conversion. Totally, 93 patients were included in the modified intention-to-treat population. The rates of sputum culture conversion were 65.2% (30/46) and 87.2% (41/47) for short-course and standard regimen group, respectively. There was no difference on two-month culture conversion rates, time to culture conversion, nor early bactericidal activity (> 0.05). However, patients on short-course regimen were observed with lower rates of radiological improvement or recovery and sustained treatment success, which was mainly attributed to higher percent of patients permanently changed assigned regimen (32.1% vs. 12.3%, = 0.012). The main cause for it was drug-induced hepatitis (16/17). Although lowering the dose of prothionamide was approved, the alternative option of changing assigned regimen was chosen in this study. While in per-protocol population, sputum culture conversion rates were 87.0% (20/23) and 94.4% (34/36) for the respective groups. Overall, the short-course regimen appeared to have inferior efficacy and higher incidence of hepatitis but desired efficacy in per-protocol population. It provides the first proof-of-concept in humans of the capacity of the short-course approach to identify drug regimens that can shorten the treatment time for tuberculosis.
Topics: Humans; Clofazimine; Prothionamide; Drug Therapy, Combination; Antitubercular Agents; Tuberculosis; Pyrazinamide; Treatment Outcome; Isoniazid
PubMed: 36872899
DOI: 10.1080/22221751.2023.2187247 -
Journal of Bacteriology Jan 2020nicotinamidase-pyrazinamidase (PZAse) is a metalloenzyme that catalyzes conversion of nicotinamide-pyrazinamide to nicotinic acid-pyrazinoic acid. This study...
nicotinamidase-pyrazinamidase (PZAse) is a metalloenzyme that catalyzes conversion of nicotinamide-pyrazinamide to nicotinic acid-pyrazinoic acid. This study investigated whether a metallochaperone is required for optimal PZAse activity. and PZAses (PZAse-MT and PZAse-EC, respectively) were inactivated by metal depletion (giving PZAse-MT-Apo and PZAse-EC-Apo). Reactivation with the metallochaperone ZnuA or Rv2059 (the analog) was measured. This was repeated following proteolytic and thermal treatment of ZnuA and Rv2059. The CDC1551 reference strain had the Rv2059 coding gene knocked out, and PZA susceptibility and the pyrazinoic acid (POA) efflux rate were measured. ZnuA (200 μM) achieved 65% PZAse-EC-Apo reactivation. Rv2059 (1 μM) and ZnuA (1 μM) achieved 69% and 34.3% PZAse-MT-Apo reactivation, respectively. Proteolytic treatment of ZnuA and Rv2059 and application of three (but not one) thermal shocks to ZnuA significantly reduced the capacity to reactivate PZAse-MT-Apo. An Rv2059 knockout strain was Wayne positive and susceptible to PZA and did not have a significantly different POA efflux rate than the reference strain, although a trend toward a lower efflux rate was observed after knockout. The metallochaperone Rv2059 restored the activity of metal-depleted PZAse Although Rv2059 is important , it seems to have a smaller effect on PZA susceptibility It may be important to mechanisms of action and resistance to pyrazinamide in Further studies are needed for confirmation. Tuberculosis is an infectious disease caused by the bacterium and remains one of the major causes of disease and death worldwide. Pyrazinamide is a key drug used in the treatment of tuberculosis, yet its mechanism of action is not fully understood, and testing strains of for pyrazinamide resistance is not easy with the tools that are presently available. The significance of the present research is that a metallochaperone-like protein may be crucial to pyrazinamide's mechanisms of action and of resistance. This may support the development of improved tools to detect pyrazinamide resistance, which would have significant implications for the clinical management of patients with tuberculosis: drug regimens that are appropriately tailored to the resistance profile of a patient's individual strain lead to better clinical outcomes, reduced onward transmission of infection, and reduction of the development of resistant strains that are more challenging and expensive to treat.
Topics: Antitubercular Agents; Drug Resistance, Bacterial; Escherichia coli; Metallochaperones; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Nicotinamidase; Pyrazinamide
PubMed: 31636108
DOI: 10.1128/JB.00331-19 -
Antimicrobial Agents and Chemotherapy Dec 2020Optimal dosing of children with tuberculous meningitis (TBM) remains uncertain and is currently based on the treatment of pulmonary tuberculosis in adults. This study...
Optimal dosing of children with tuberculous meningitis (TBM) remains uncertain and is currently based on the treatment of pulmonary tuberculosis in adults. This study aimed to investigate the population pharmacokinetics of isoniazid, rifampin, pyrazinamide, and ethambutol in Vietnamese children with TBM, to propose optimal dosing in these patients, and to determine the relationship between drug exposure and treatment outcome. A total of 100 Vietnamese children with TBM were treated with an 8-month antituberculosis regimen. Nonlinear mixed-effects modeling was used to evaluate the pharmacokinetic properties of the four drugs and to simulate different dosing strategies. The pharmacokinetic properties of rifampin and pyrazinamide in plasma were described successfully by one-compartment disposition models, while those of isoniazid and ethambutol in plasma were described by two-compartment disposition models. All drug models included allometric scaling of body weight and enzyme maturation during the first years of life. Cerebrospinal fluid (CSF) penetration of rifampin was relatively poor and increased with increasing protein levels in CSF, a marker of CSF inflammation. Isoniazid and pyrazinamide showed good CSF penetration. Currently recommended doses of isoniazid and pyrazinamide, but not ethambutol and rifampin, were sufficient to achieve target exposures. The ethambutol dose cannot be increased because of ocular toxicity. Simulation results suggested that rifampin dosing at 50 mg/kg of body weight/day would be required to achieve the target exposure. Moreover, low rifampin plasma exposure was associated with an increased risk of neurological disability. Therefore, higher doses of rifampin could be considered, but further studies are needed to establish the safety and efficacy of increased dosing.
Topics: Adult; Antitubercular Agents; Asian People; Child; Ethambutol; Humans; Isoniazid; Pyrazinamide; Tuberculosis, Meningeal
PubMed: 33139294
DOI: 10.1128/AAC.00487-20 -
International Journal of Environmental... Jan 2022Tuberculosis (TB), the most frequent bacterium-mediated infectious disease caused by , has been known to infect humans since ancient times. Although TB is common...
Tuberculosis (TB), the most frequent bacterium-mediated infectious disease caused by , has been known to infect humans since ancient times. Although TB is common worldwide, the most recent report by the WHO (World Health Organization) listed the three countries of India, China, and Russia with 27%, 14%, and 8% of the global burden of TB, respectively. It has been reported that resistance to TB drugs, particularly by the gene to the pyrazinamide drug due to mutations, significantly affects the effective treatment of TB. Understanding the mechanism of drug resistance using computational methods is of great interest to design effective TB treatment, exploring the structural features with these tools. Thus, keeping in view the importance of these methods, we employed state-of-the-art computational methods to study the mechanism of resistance caused by the W68L, L85P, and T87A mutations recently reported in 2021. We employed a molecular docking approach to predict the binding conformation and studied the dynamic properties of each complex using molecular dynamics simulation approaches. Our analysis revealed that compared to the wildtype, these three mutations altered the binding pattern and reduced the binding affinity. Moreover, the structural dynamic features also showed that these mutations significantly reduced the structural stability and packing, particularly by the W68L and L85P mutations. Moreover, principal component analysis, free energy landscape, and the binding free energy results revealed variation in the protein's motion and the binding energy. The total binding free energy was for the wildtype -9.61 kcal/mol, W68L -7.57 kcal/mol, L85P -6.99 kcal/mol, and T87A -7.77 kcal/mol. Our findings can help to design a structure-based drug against the MDR (multiple drug-resistant) TB.
Topics: Amidohydrolases; Antitubercular Agents; Drug Resistance, Bacterial; Microbial Sensitivity Tests; Molecular Docking Simulation; Mutation; Mycobacterium tuberculosis; Pyrazinamide
PubMed: 35162636
DOI: 10.3390/ijerph19031615 -
Antimicrobial Agents and Chemotherapy Aug 2021Heteroresistance is defined as the coexistence of both susceptible and resistant bacteria in a bacterial population. Previously published data show that it may occur in...
Heteroresistance is defined as the coexistence of both susceptible and resistant bacteria in a bacterial population. Previously published data show that it may occur in 9 to 57% of Mycobacterium tuberculosis isolates for various drugs. Pyrazinamide (PZA) is an important first-line drug used for treatment of both drug-susceptible and PZA-susceptible multidrug-resistant TB. Clinical PZA resistance is defined as a proportion of resistant bacteria in the isolate exceeding 10%, when the drug is no longer considered clinically effective. The ability of traditional drug susceptibility testing techniques to detect PZA heteroresistance has not yet been evaluated. The aim of this study was to compare the capacity of Bactec MGIT 960, Wayne's test, and whole-genome sequencing (WGS) to detect PZA-resistant subpopulations in bacterial suspensions prepared with different proportions of mutant strains. Both Bactec MGIT 960 and WGS were able to detect the critical level of 10% PZA heteroresistance, whereas Wayne's test failed to do so, with the latter falsely reporting highly resistant samples as PZA susceptible. Failure to detect drug-resistant subpopulations may lead to inadvertently weak treatment regimens if ineffective drugs are included, with the risk of treatment failure with the selective growth of resistant subpopulations. We need clinical awareness of heteroresistance as well as evaluation of new diagnostic tools for their capacity to detect heteroresistance in TB.
Topics: Amidohydrolases; Antitubercular Agents; Drug Resistance, Bacterial; Humans; Microbial Sensitivity Tests; Mutation; Mycobacterium tuberculosis; Pyrazinamide; Tuberculosis, Multidrug-Resistant
PubMed: 34181476
DOI: 10.1128/AAC.00720-21 -
PloS One 2022Ethiopia is one of the high multidrug-resistant tuberculosis (MDR-TB) burden countries. However, phenotypic drug susceptibility testing can take several weeks due to the...
Prediction of drug resistance by Sanger sequencing of Mycobacterium tuberculosis complex strains isolated from multidrug resistant tuberculosis suspect patients in Ethiopia.
BACKGROUND
Ethiopia is one of the high multidrug-resistant tuberculosis (MDR-TB) burden countries. However, phenotypic drug susceptibility testing can take several weeks due to the slow growth of Mycobacterium tuberculosis complex (MTBC) strains. In this study, we assessed the performance of a Sanger sequencing approach to predict resistance against five anti-tuberculosis drugs and the pattern of resistance mediating mutations.
METHODS
We enrolled 226 MTBC culture-positive MDR-TB suspects and collected sputum specimens and socio-demographic and TB related data from each suspect between June 2015 and December 2016 in Addis Ababa, Ethiopia. Phenotypic drug susceptibility testing (pDST) for rifampicin, isoniazid, pyrazinamide, ethambutol, and streptomycin using BACTEC MGIT 960 was compared with the results of a Sanger sequencing analysis of seven resistance determining regions in the genes rpoB, katG, fabG-inhA, pncA, embB, rpsL, and rrs.
RESULT
DNA isolation for Sanger sequencing was successfully extracted from 92.5% (209/226) of the MTBC positive cultures, and the remaining 7.5% (17/226) strains were excluded from the final analysis. Based on pDST results, drug resistance proportions were as follows: isoniazid: 109/209 (52.2%), streptomycin: 93/209 (44.5%), rifampicin: 88/209 (42.1%), ethambutol: 74/209 (35.4%), and pyrazinamide: 69/209 (33.0%). Resistance against isoniazid was mainly mediated by the mutation katG S315T (97/209, 46.4%) and resistance against rifampicin by rpoB S531L (58/209, 27.8%). The dominating resistance-conferring mutations for ethambutol, streptomycin, and pyrazinamide affected codon 306 in embB (48/209, 21.1%), codon 88 in rpsL (43/209, 20.6%), and codon 65 in pncA (19/209, 9.1%), respectively. We observed a high agreement between phenotypic and genotypic DST, such as 89.9% (at 95% confidence interval [CI], 84.2%-95.8%) for isoniazid, 95.5% (95% CI, 91.2%-99.8%) for rifampicin, 98.6% (95% CI, 95.9-100%) for ethambutol, 91.3% (95% CI, 84.6-98.1%) for pyrazinamide and 57.0% (95% CI, 46.9%-67.1%) for streptomycin.
CONCLUSION
We detected canonical mutations implicated in resistance to rifampicin, isoniazid, pyrazinamide, ethambutol, and streptomycin. High agreement with phenotypic DST results for all drugs renders Sanger sequencing promising to be performed as a complementary measure to routine phenotypic DST in Ethiopia. Sanger sequencing directly from sputum may accelerate accurate clinical decision-making in the future.
Topics: Antitubercular Agents; Drug Resistance, Multiple, Bacterial; Ethambutol; Ethiopia; Humans; Isoniazid; Microbial Sensitivity Tests; Mutation; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Streptomycin; Tuberculosis, Multidrug-Resistant
PubMed: 35930613
DOI: 10.1371/journal.pone.0271508 -
PloS One 2015Pyrazinamide (PZA) is crucial for tuberculosis (TB) treatment, given its unique ability to eradicate persister bacilli. The worldwide burden of PZA resistance remains... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Pyrazinamide (PZA) is crucial for tuberculosis (TB) treatment, given its unique ability to eradicate persister bacilli. The worldwide burden of PZA resistance remains poorly described.
METHODS
Systematic PubMed, Science Direct and Scopus searches for articles reporting phenotypic (liquid culture drug susceptibility testing or pyrazinamidase activity assays) and/or genotypic (polymerase chain reaction or DNA sequencing) PZA resistance. Global and regional summary estimates were obtained from random-effects meta-analysis, stratified by presence or risk of multidrug resistant TB (MDR-TB). Regional summary estimates were combined with regional WHO TB incidence estimates to determine the annual burden of PZA resistance. Information on single nucleotide polymorphisms (SNPs) in the pncA gene was aggregated to obtain a global summary.
RESULTS
Pooled PZA resistance prevalence estimate was 16.2% (95% CI 11.2-21.2) among all TB cases, 41.3% (29.0-53.7) among patients at high MDR-TB risk, and 60.5% (52.3-68.6) among MDR-TB cases. The estimated global burden is 1.4 million new PZA resistant TB cases annually, about 270,000 in MDR-TB patients. Among 1,815 phenotypically resistant isolates, 608 unique SNPs occurred at 397 distinct positions throughout the pncA gene.
INTERPRETATION
PZA resistance is ubiquitous, with an estimated one in six incident TB cases and more than half of all MDR-TB cases resistant to PZA globally. The diversity of SNPs across the pncA gene complicates the development of rapid molecular diagnostics. These findings caution against relying on PZA in current and future TB drug regimens, especially in MDR-TB patients.
Topics: Antitubercular Agents; Humans; Mycobacterium tuberculosis; Pyrazinamide; Tuberculosis, Multidrug-Resistant
PubMed: 26218737
DOI: 10.1371/journal.pone.0133869