Doses Of Isoniazid Research Articles

Hepatotoxicity during anti tuberculosis chemotherapy

Introduction: Despite their efficacy in tuberculosis treatment, side-effects of anti-tuberculosis drugs can be serious or fatal. The aim of our study is to determine the prevalence of hepatic toxicities associated with anti-tuberculosis drugs, their evolutionary aspects, and their management. Patients and methods: A retrospective descriptive study including 82 patients having received antituberculosis treatment and who pre-sented a hepatic cytolysis, collected at the Tuberculosis and Respiratory Diseases Control Department of Batna- Algeria between 2016 -2023. The aim of our study is to determine the prevalence of hepatic toxicities of anti-tuberculosis drugs, their evolutionary aspects, as well as the modalities of their management. Results: 82 out of 119 (69.23%) patients who experienced other adverse events were recruited between 2016 and 2023, aged between 15 and 86 years, with an average age of 43 years and a female predominance of 63.41%. Cholestasis syndrome was noted in 21 patients and frank jaundice in 4. Cytolysis was discovered incidentally in 68% of patients; it was mild in 56 (68.29%), moderate in 16 (19.51%) and severe in 10 (12.19%). Transaminase disturbance appeared within 3 months in 76.82% of cases, whereas a delay of 30 days was noted for normalisation of the liver function test after cessation of anti-tuberculosis treatment in 62 (76%) patients. Definitive discontin-uation of isoniazid (INH) was adopted in 17 (20%) patients, while a reduction in the doses of rifampicin and isoniazid was decided in 65 (80%) patients. Conclusion: Drug-induced hepatitis is one of the major side-effects of anti-tuberculosis drugs and can be lethal, hence the need for rapid and appropriate management. Healthcare professionals need to be informed about the types of suspected adverse drug reactions, they should report in subjects at risk.

Machine Learning Approach in Dosage Individualization of Isoniazid for Tuberculosis.

Isoniazid is a first-line antituberculosis agent with high variability, which would profit from individualized dosing. Concentrations of isoniazid at 2 h (C2h), as an indicator of safety and efficacy, are important for optimizing therapy. The objective of this study was to establish machine learning (ML) models to predict the C2h, that can be used for establishing an individualized dosing regimen in clinical practice. Published population pharmacokinetic (PopPK) models for adults were searched based on PubMed and ultimately four reliable models were selected for simulating individual C2h datasets under different conditions (demographics, genotype, ethnicity, etc.). Machine learning models were trained on simulated C2h obtained from the four PopPK models. Five different algorithms were used for ML model building to predict C2h. Real-world data were used for predictive performance evaluations. Virtual trials were used to compare ML-optimized doses with PopPK model-optimized doses. Categorical boosting (CatBoost) exhibited the highest prediction ability. Target C2h can be predicted using the ML model combined with the dosing regimen and three covariates (N-acetyltransferase 2 [NAT2] genotypes, weight and race [Asians and Africans]). Real-world data validation results showed that the ML model can achieve an overall prediction accuracy of 93.4%. Using the final ML model, the mean absolute prediction error value decreased by 45.7% relative to the average of PopPK models. Using the ML-optimized dosing regimen, the probability of target attainment increased by 43.7% relative to the PopPK model-optimized dosing regimens. Machine learning models were developed with great predictive performance, which can be used to determine the individualized initial dose of isoniazid in adult patients.

Measurement of isoniazid in tuberculosis patients using finger sweat with creatinine normalisation: A controlled administration study

BackgroundInsufficient exposure and poor compliance with anti-tuberculosis (TB) medications are risk factors for treatment failure and the development of drug resistance. Measurement of drugs in biological samples, such as blood and saliva, can be used to assess adherence and make dose adjustments by therapeutic drug monitoring (TDM). Finger sweat testing is a convenient and non-invasive method to monitor patients. ObjectivesTo assess the feasibility of finger sweat testing for medication adherence and as a semi-quantitative tool for TDM analysis. MethodsTen patients provided finger sweat, blood and saliva samples following a controlled dose of isoniazid. Samples were analysed by liquid chromatography-mass spectrometry. ResultsIsoniazid can be detected in finger sweat 1–6 h following administration at typically prescribed dosages. The normalisation of isoniazid to creatinine increases the correlation between finger sweat and serum isoniazid concentration and provides a means to account for inconsistent sample volumes. ConclusionWe describe the time-course measurement of isoniazid (or drug-to-creatinine ratio) in finger sweat compared to the pharmacokinetic profile in blood for the first time. This technique, adaptable for other drugs, could reduce the burden on clinics and improve patient experience.

Genetic and clinical predictors of rifapentine and isoniazid pharmacokinetics in paediatrics with tuberculosis infection.

Twelve weekly doses of rifapentine and isoniazid (3HP regimen) are recommended for TB preventive therapy in children with TB infection. However, they present with variability in the pharmacokinetic profiles. The current study aimed to develop a pharmacokinetic model of rifapentine and isoniazid in 12 children with TB infection using NONMEM. Ninety plasma and 41 urine samples were collected at Week 4 of treatment. Drug concentrations were measured using a validated HPLC-UV method. MassARRAY® SNP genotyping was used to investigate genetic factors, including P-glycoprotein (ABCB1), solute carrier organic anion transporter B1 (SLCO1B1), arylacetamide deacetylase (AADAC) and N-acetyl transferase (NAT2). Clinically relevant covariates were also analysed. A two-compartment model for isoniazid and a one-compartment model for rifapentine with transit compartment absorption and first-order elimination were the best models for describing plasma and urine data. The estimated (relative standard error, RSE) of isoniazid non-renal clearance was 3.52 L·h-1 (23.1%), 2.91 L·h-1 (19.6%), and 2.58 L·h-1 (20.0%) in NAT2 rapid, intermediate and slow acetylators. A significant proportion of the unchanged isoniazid was cleared renally (2.7 L·h-1; 8.0%), while the unchanged rifapentine was cleared primarily through non-renal routes (0.681 L·h-1; 3.6%). Participants with the ABCB1 mutant allele had lower bioavailability of rifapentine, while food prolonged the mean transit time of isoniazid. ABCB1 mutant allele carriers may require higher rifapentine doses; however, this must be confirmed in larger trials. Food did not affect overall exposure to isoniazid and only delayed absorption time.

Efficacy of Short-course Weekly Isoniazid and Rifapentine Regimen as Tuberculosis Preventive Treatment among Population at Risk of Developing Disease: A Systematic Review and Meta-analysis

Introduction: Tuberculosis (TB) remains a major public health problem in India. Individuals with latent infection do not have active disease and cannot spread Tuberculosis Infection (TBI). The prevalence of latent TB in India is very high, ranging from 40-50%. About 5 to 10% of them may convert into active TB disease. The national program primarily recommends treatment for active TB, while treatment of latent TB is recommended only in special situations. Aim: To assess the efficacy of short-course weekly Isoniazid and Rifapentine (HP) regimen as Tuberculosis Preventive Treatment (TPT) among various risk groups. Materials and Methods: A systematic review and meta-analysis were conducted, involving of about 10 Randomised Control Trials (RCTs). Studies published between 2006 and 2023 were included. Online databases such as PubMed, Google Scholar, Clinical Trial Registry India, and grey literature were searched using keywords like Isoniazid, Rifapentine, and trial. Results: In terms of TB incidence, the pooled risk ratio favoured the weekly HP regimen, estimated at 0.69 (0.49, 0.97, 95% CI). Regarding the incidence of hepatotoxicity, the weekly HP regimen showed neither superiority nor inferiority to comparators, with a pooled risk ratio of 0.50 (0.23, 1.05, 95% CI). The odds of completing treatment were 2.19 times greater for the weekly HP regimen than for controls, with a pooled odds ratio of 2.19 (1.64, 2.92; 95% CI). Conclusion: The weekly HP regimen is superior to other regimens in reducing the incidence of TB. Additionally, the duration of the HP regimen is shorter compared to the commonly advised nine-month Isoniazid regimen. Compared with the daily dosage of Isoniazid, the weekly HP regimen offers better compliance. It also exhibits a significantly higher treatment completion rate. In summary, the weekly HP regimen is superior to other regimens.

Application of the Hollow-Fiber Infection Model to Personalized Precision Dosing of Isoniazid in a Clinical Setting.

The hollow-fiber infection model (HFIM) is a valuable tool for evaluating pharmacokinetics/pharmacodynamics relationships and determining the optimal antibiotic dose in monotherapy or combination therapy, but the application for personalized precision medicine in tuberculosis treatment remains limited. This study aimed to evaluate the efficacy of adjusted antibiotic doses for a tuberculosis patient using HFIM. Model-based Bayesian forecasting was utilized to assess the proposed reduction of the isoniazid dose from 300 mg daily to 150 mg daily in a patient with an ultra-slow-acetylation phenotype. The efficacy of the adjusted 150-mg dose was evaluated in a time-to-kill assay performed using the bacterial isolate Mycobacterium tuberculosis (Mtb) H37Ra in a HFIM that mimicked the individual pharmacokinetic profile of the patient. The isoniazid concentration observed in the HFIM adequately reflected the target drug exposures simulated by the model. After 7 days of repeated dose administration, isoniazid killed 4 log10 Mtb CFU/mL in the treatment arm, while the control arm without isoniazid increased 1.6 log10 CFU/mL. Our results provide an example of the utility of the HFIM for predicting the efficacy of specific recommended doses of anti-tuberculosis drugs in real clinical setting.

Isoniazid exposures and acetylator status in Indonesian tuberculous meningitis patients

The effect of acetylator status on the exposure to isoniazid in plasma and CSF in tuberculous meningitis (TBM) patients remains largely unexplored. Here, we describe isoniazid exposures and acetylator status of 48 subjects in the ReDEFINe study (NCT02169882). Fifty percentwere fast (half-life <130 min) or slow (half-life >130 min) acetylators. Slow acetylators had higher AUC0-24, Cmax and CSF concentrations than fast acetylators (GM AUC0-24 25.5 vs 10.6 mg/L*h, p < 0.001); plasma Cmax 5.5 vs 3.6 mg/L, p = 0.023; CSF concentration 1.9 vs 1.1 mg/L, p = 0.008). Higher isoniazid doses may benefit fast acetylators in TBM.

Transcriptional adaptation of Mycobacterium tuberculosis that survives prolonged multi-drug treatment in mice.

A major reason that curing tuberculosis requires prolonged treatment is that drug exposure changes bacterial phenotypes. The physiologic adaptations of Mycobacterium tuberculosis that survive drug exposure in vivo have been obscure due to low sensitivity of existing methods in drug-treated animals. Using the novel SEARCH-TB RNA-seq platform, we elucidated Mycobacterium tuberculosis phenotypes in mice treated for with the global standard 4-drug regimen and compared them with the effect of the same regimen in vitro. This first view of the transcriptome of the minority Mycobacterium tuberculosis population that withstands treatment in vivo reveals adaptation of a broad range of cellular processes, including a shift in metabolism and cell wall modification. Surprisingly, the change in gene expression induced by treatment in vivo and in vitro was largely similar. This apparent "portability" from in vitro to the mouse provides important new context for in vitro transcriptional analyses that may support early preclinical drug evaluation.

Isoniazid-induced liver injury risk level in different variants of N-acetyltransferase 2 (NAT2) polymorphisms: A literature review

Individual NAT2 genotype identity data should be enriched to prevent Isoniazid-induced liver injury (IDILI) and optimize the dose of Isoniazid (INH). Therefore, this study aims to present the level of IDILI risk for specific genotype alleles. The data collection involves literature indexed by Google Scholar, Scopus, and Pubmed databases. The search uses a combination of the following keyword variants “INH” OR “INH”, “liver injury” OR “hepatotoxicity”, “polymorphism” OR “pharmacogenomic”, and “N-acetyltransferase 2” OR “NAT2”. Furthermore, the screening results of library sources were narrowed to 11 original articles that met the inclusion criteria. The IDILI risk assessment analysis due to NAT2 enzyme polymorphism following the odds ratio has a 95% confidence interval. The results showed that the IDILI risk level of the slow acetylator group was 3.11 times higher than other populations. Meanwhile, the rapid and intermediate acetylator groups were not at risk. Three variants related to *6 allele were classified as high risk; *6A/*6A risk 5.76 times, *6A/*7B (5.54 times), and *6/*7 (4 times). The three allele configurations of the *5 and *7 were also classified as a risk; *5B/*7B (5 times), *7B/*7B (3.23 times), and *5/*7 (2,74 times).

Retracted: The Impact of a Knowledge Discovery-Based Psychoanalytic Intervention in the Treatment of Tuberculosis in University Students with Different Doses of Isoniazid.

[This retracts the article DOI: 10.1155/2022/5610469.].

Correlation of N-acetyltransferase 2 genotype and acetylation status with plasma isoniazid concentration and its metabolic ratio in ethiopian tuberculosis patients

Unfavorable treatment outcomes for tuberculosis (TB) treatment might result from altered plasma exposure to antitubercular drugs in TB patients. The present study investigated the distribution of the N-Acetyltransferase 2 (NAT2) genotype, isoniazid acetylation status, genotype–phenotype concordance of NAT2, and isoniazid plasma exposure among Ethiopian tuberculosis patients. Blood samples were collected from newly diagnosed TB patients receiving a fixed dose combination of first-line antitubercular drugs daily. Genotyping of NAT2 was done using TaqMan drug metabolism assay. Isoniazid and its metabolite concentration were determined using validated liquid chromatography-tandem mass spectrometry (LC–MS/MS). A total of 120 patients (63 male and 57 female) were enrolled in this study. The mean daily dose of isoniazid was 4.71 mg/kg. The frequency of slow, intermediate, and fast NAT2 acetylators genotypes were 74.2%, 22.4%, and 3.3% respectively. The overall median isoniazid maximum plasma concentration (Cmax) was 4.77 µg/mL and the AUC0–7 h was 11.21 µg.h/mL. The median Cmax in slow, intermediate, and fast acetylators were 5.65, 3.44, and 2.47 μg/mL, respectively. The median AUC0–7 h hour in slow, intermediate, and fast acetylators were 13.1, 6.086, and 3.73 mg•h/L, respectively. The majority (87.5%) of the study participants achieved isoniazid Cmax of above 3 µg/mL, which is considered a lower limit for a favorable treatment outcome. There is 85% concordance between the NAT2 genotype and acetylation phenotypes. NAT2 genotype, female sex, and dose were independent predictors of Cmax and AUC0–7 h (p < 0.001). Our finding revealed that there is a high frequency of slow NAT2 genotypes. The plasma Cmax of isoniazid was higher in the female and slow acetylators genotype group. The overall target plasma isoniazid concentrations in Ethiopian tuberculosis patients were achieved in the majority of the patients. Therefore, it is important to monitor adverse drug reactions and the use of a higher dose of isoniazid should be closely monitored.

Molecular and cellular remodeling of HepG2 cells upon treatment with antitubercular drugs.

Drug-induced liver injury (DILI) is an adverse outcome of the currently used tuberculosis treatment regimen, which results in patient noncompliance, poor treatment outcomes, and the emergence of drug-resistant tuberculosis. DILI is primarily caused by the toxicity of the drugs and their metabolites, which affect liver cells, biliary epithelial cells, and liver vasculature. However, the precise mechanism behind the cellular damage attributable to first-line antitubercular drugs (ATDs), as well as the effect of toxicity on the cell survival strategies, is yet to be elucidated. In the current study, HepG2 cells upon treatment with a high concentration of ATDs showed increased perforation within the cell, cuboidal shape, and membrane blebbing as compared with control/untreated cells. It was observed that ATD-induced toxicity in HepG2 cells leads to altered mitochondrial membrane permeability, which was depicted by the decreased fluorescence intensity of the MitoRed tracker dye at higher drug concentrations. In addition, high doses of ATDs caused cell damage through an increase in reactive oxygen species production in HepG2 cells and a simultaneous reduction in glutathione levels. Further, high dose of isoniazid (50-200 mM), pyrazinamide (50-200 mM), and rifampicin (20-100 µM) causes cell apoptosis and affects cell survival during toxic conditions by decreasing the expression of potent autophagy markers Atg5, Atg7, and LC3B. Thus, ATD-mediated toxicity contributes to the reduced ability of hepatocytes to tolerate cellular damage caused by altered mitochondrial membrane permeability, increased apoptosis, and decreased autophagy. These findings further emphasize the need to develop adjuvant therapies that can mitigate ATD-induced toxicity for the effective treatment of tuberculosis.

High rate of adverse drug reactions with a novel tuberculosis re-treatment regimen combining triple doses of both isoniazid and rifampicin

ObjectivesHigh-dose rifampicin (R) and isoniazid (H) are known to be safe but were not yet combined in a single regimen. The primary objective of the TRIple-DOse RE-treatment (TRIDORE) study is to determine whether a 6-month firstline regimen with triple dose of both R and H (intervention arm; 6R3H3ZE) is non-inferior in terms of safety compared to a normal-dose regimen (6RHZE) in previously treated patients with R-susceptible (Rs) recurrent tuberculosis (TB). Design/methodsTRIDORE is an ongoing pragmatic open-label multi-stage randomized clinical trial. ResultsBetween March 2021 and February 2022, 127 consenting patients were randomly assigned to either the intervention or control arm: 62 and 65 were treated with 6R3H3ZE and 6RHZE, respectively. Of 127, 111 (87.4%) were male and the median age (interquartile range) was 37 (30-48) years. The median body mass index at enrollment was 18.1 (16.3-19.7) kg/m2. Drugrelated severe adverse events (AEs) (grade III-V) were significantly more frequent when 6R3H3ZE was used (5/62 vs 0/65, P = 0.03, difference weighted for site 8% [95% confidence interval: 1.0,14.3]). The Data and Safety Monitoring Board recommended publishing our interim safety data analysis. ConclusionWe show that the combination of triple-dose R with triple-dose H in a re-treatment regimen for patients with Rs-TB causes excess drug-related AEs.

A model-based approach for a practical dosing strategy for the short, intensive treatment regimen for paediatric tuberculous meningitis.

Following infection with Mycobacterium tuberculosis, young children are at high risk of developing severe forms of tuberculosis (TB) disease, including TB meningitis (TBM), which is associated with significant morbidity and mortality. In 2022, the World Health Organization (WHO) conditionally recommended that a 6-month treatment regimen composed of higher doses of isoniazid (H) and rifampicin (R), with pyrazinamide (Z) and ethionamide (Eto) (6HRZEto), be used as an alternative to the standard 12-month regimen (2HRZ-Ethambutol/10HR) in children and adolescents with bacteriologically confirmed or clinically diagnosed TBM. This regimen has been used in South Africa since 1985, in a complex dosing scheme across weight bands using fixed-dose combinations (FDC) available locally at the time. This paper describes the methodology used to develop a new dosing strategy to facilitate implementation of the short TBM regimen based on newer globally available drug formulations. Several dosing options were simulated in a virtual representative population of children using population PK modelling. The exposure target was in line with the TBM regimen implemented in South Africa. The results were presented to a WHO convened expert meeting. Given the difficulty to achieve simple dosing using the globally available RH 75/50mg FDC, the panel expressed the preference to target a slightly higher rifampicin exposure while keeping isoniazid exposures in line with those used in South Africa. This work informed the WHO operational handbook on the management of TB in children and adolescents, in which dosing strategies for children with TBM using the short TBM treatment regimen are provided.

Factors associated with non-completion of TB preventive treatment in Brazil.

BACKGROUND: Among Brazilian initiatives to scale up TB preventive therapy (TPT) are the adoption of the 3HP regimen (12 weekly doses of rifapentine and isoniazid [INH]) in 2021 and the implementation in 2018 of the TPT surveillance information system. Since then, 63% of the 76,000 eligible individuals notified completed TPT. Recommended regimens in this period were 6H, 9H (6 or 9 months of INH) and 4R (4 months of rifampicin).OBJECTIVE: To analyse the factors associated with TPT non-completion.METHODS: We analysed the cohort of TPT notifications from 2018 to 2020. Robust variance Poisson regression model was used to verify the association of TPT non-completion with sociodemographic, clinical and epidemiological variables.RESULTS: Of the 39,973 TPT notified in the study period, 8,534 (21.5%) were non-completed, of which 7,858 (92.1%) were lost to follow-up. Age 15-60 years (relative risk [RR] 1.27, 95% confidence interval [95% CI] 1.20-1.35), TPT with isoniazid (RR 1.40, 95% CI 1.19-1.64) and Black/mixed race (RR 1.17, 95% CI 1.09-1.25) were associated with a higher risk of non-completion.CONCLUSION: Individuals in situations of social and financial vulnerability such as being Black/pardo race, younger and on longer TPT regimens were more likely to be associated with TPT incompletion.

Adequacy of the 10 mg/kg Daily Dose of Antituberculosis Drug Isoniazid in Infants under 6 Months of Age.

In 2010, the WHO recommended an increase in the daily doses of first-line anti-tuberculosis medicines in children. We aim to characterize the pharmacokinetics of the once-daily isoniazid (INH) dose at 10 mg/kg of body weight in infants <6 months of age. We performed a multicenter pharmacokinetic study in Spain. The N-acetyltransferase 2 gene was analyzed to determine the acetylation status. Samples were analyzed using a validated UPLC-UV assay. A non-compartmental pharmacokinetic analysis was performed. Twenty-three pharmacokinetic profiles were performed in 20 infants (8 females) at a median (IQR) age of 19.0 (12.6-23.3) weeks. The acetylator statuses were homozygous fast (n = 1), heterozygous intermediate (n = 12), and homozygous slow (n = 7). INH median (IQR) Cmax and AUC0-24h values were 4.8 (3.7-6.7) mg/L and 23.5 (13.4-36.7) h*mg/L and the adult targets (>3 mg/L and 11.6-26.3 h*mg/L) were not reached in three and five cases, respectively. The age at assessment or acetylator status had no impact on Cmax values, but a larger INH AUC0-24h (p = 0.025) and trends towards a longer half-life (p = 0.055) and slower clearance (p = 0.070) were observed in homozygous slow acetylators. Treatment was well tolerated; mildly elevated alanine aminotransferase levels were observed in three cases. In our series of young infants receiving isoniazid, no major safety concerns were raised, and the target adult levels were reached in most patients.

Isoniazid pharmacokinetics/pharmacodynamics as monotherapy and in combination regimen in the hollow fiber system model of Mycobacterium kansasii

BackgroundThere is limited high quality evidence to guide the optimal doses of drugs for the treatment of Mycobacterium kansasii pulmonary disease (Mkn-PD). MethodsWe performed (1) minimum inhibitory concentration experiment, (2) isoniazid dose-response study using the hollow fiber system model (HFS-Mkn) to determine PK/PD optimized exposure, and (3) another HFS-Mkn study to determine the efficacy of high dose isoniazid (15 mg/kg/day) with standard dose rifampin (10 mg/kg/day) and ethambutol (15 mg/kg/day). Inhibitory sigmoid maximal effect model and linear regression was used for data analysis. ResultsMIC of the 20 clinical isolates ranged between 0.5 mg/L to 32 mg/L. In the HFS-Mkn, isoniazid monotherapy failed to control the bacterial growth beyond day 7. On day 7, when the maximal Mkn kill was observed, the optimal isoniazid exposure for Mkn kill was calculated as 24hr area under the concentration-time curve to the MIC of 12.41. Target attainment probability of 300 mg/day dose fell below 90% above the MIC of 1 mg/L. High dose isoniazid combination sterilized the HFS-Mkn in 30-days with a kill rate of −0.15 ± 0.02 log10 CFU/mL/day. ConclusionDespite initial kill, isoniazid monotherapy failed due to resistance emergence. Our pre-clinical model derived results suggest that higher than currently recommended 300 mg/day isoniazid dose may achieve better clinical efficacy against Mkn-PD.

Bedaquiline-Based Short Course Regime for MDR-TB -“The Indian Scenario”

India ranks highest in number of Tuberculosis (TB) and Multi Drug Resistant (MDR) TB patients globally (World Health Organization. Global tuberculosis report (2018). Maximum number of deaths due to TB also occur in India. A short course regime for treating Fluroquinolone (FQ) Sensitive MDR TB has been recommended by the World Health Organization (WHO) in 2020 with a duration of 9-11 months. India has also adopted the BDQ Short course regime for MDR-TB patients with multiple exclusion criteria. The excluded patients would receive a longer BDQ based regime which may last 18-20 months. The purpose of this mini-review is to emphasize the possibilities of high failure rates in the BDQ based short course regime, especially in the Context of India due to high baseline FQ resistance and an acute shortage of Drug Sensitivity Tests (DST) tests especially for FQ. Moreover, the need of High dose Isoniazid (Hh ) in the regime may be only a toxic addition in about 80% of patients leading to adverse effects, some of which may be fatal. Failure of BDQ-based short course regime would lead to a catastrophic amplification of the resistance of critically essential drugs such as BDQ and Clofazimine (CFZ). Chances of cure in such patients with Extensively Drug Resistant (XDR) TB would be slim, if not altogether absent.

Isoniazid and rifapentine treatment effectively reduces persistent M. tuberculosis infection in macaque lungs.

A once-weekly oral dose of isoniazid and rifapentine for 3 months (3HP) is recommended by the CDC for treatment of latent tuberculosis infection (LTBI). The aim of this study is to assess 3HP-mediated clearance of M. tuberculosis bacteria in macaques with asymptomatic LTBI. Twelve Indian-origin rhesus macaques were infected with a low dose (~10 CFU) of M. tuberculosis CDC1551 via aerosol. Six animals were treated with 3HP and 6 were left untreated. The animals were imaged via PET/CT at frequent intervals. Upon treatment completion, all animals except 1 were coinfected with SIV to assess reactivation of LTBI to active tuberculosis (ATB). Four of 6 treated macaques showed no evidence of persistent bacilli or extrapulmonary spread until the study end point. PET/CT demonstrated the presence of significantly more granulomas in untreated animals relative to the treated group. The untreated animals harbored persistent bacilli and demonstrated tuberculosis (TB) reactivation following SIV coinfection, while none of the treated animals reactivated to ATB. 3HP treatment effectively reduced persistent infection with M. tuberculosis and prevented reactivation of TB in latently infected macaques.

Minimum inhibitory concentrations of rifampin and isoniazid among multidrug and isoniazid resistant Mycobacterium tuberculosis in Ethiopia.

Traditionally, single critical concentrations of drugs are utilized for Mycobacterium tuberculosis (Mtb) drug susceptibility testing (DST); however, the level of drug resistance can impact treatment choices and outcomes. Mutations at the katG gene are the major genetic mutations in multidrug resistant (MDR) Mtb and usually associated with high level resistance. We assessed the minimum inhibitory concentrations (MICs) of MDR or rifampin resistant (RR) and isoniazid (INH) resistant Mtb isolates to determine the quantification of drug resistance among key anti-tuberculosis drugs. The study was conducted on stored Mtb isolates collected as part of a national drug resistance survey in Ethiopia. MIC values were determined using Sensititre™ MYCOTB plates. A line probe assay (MTBDRplus) was also performed to identify genetic determinants of resistance for all isolates. MIC testing was performed on 74 Mtb isolates including 46 MDR, 2 RR and 26 INH phenotypically resistant isolates as determined by the Löwenstein Jensen (LJ) method. Four (15%) INH resistant Mtb isolates were detected as borderline rifampin resistance (MIC = 1 μg/ml) using MYCOTB MIC plates and no rifampin resistance mutations were detected by LPA. Among the 48 MDR/RR TB cases, 9 (19%) were rifabutin susceptible (MIC was between ≤0.25 and 0.5μg/ml). Additionally, the MIC for isoniazid was between 2-4 μg/ml (moderate resistance) for 58% of MDR TB isolates and 95.6% (n = 25) of the isolates had mutations at the katG gene. Our findings suggest a role for rifabutin treatment in a subset of RR TB patients, thus potentially preserving an important drug class. The high proportion of moderate level INH resistant among MDR Mtb isolates indicates the potential benefit of high dose isoniazid treatment in a high proportion of katG gene harboring MDR Mtb isolates.