Treatment Outcomes Among Pediatric Patients With Highly Drug-Resistant Tuberculosis: The Role of New and Repurposed Second-Line Tuberculosis Drugs

Population pharmacokinetics and dose evaluations of linezolid in the treatment of multidrug-resistant tuberculosis

Background: The pharmacokinetic/pharmacodynamics (PK/PD) target derived from the hollow-fiber system model for linezolid for treatment of the multidrug-resistant tuberculosis (MDR-TB) requires clinical validation. Therefore, this study aimed to develop a population PK model for linezolid when administered as part of a standardized treatment regimen, to identify the PK/PD threshold associated with successful treatment outcomes and to evaluate currently recommended linezolid doses. Method: This prospective multi-center cohort study of participants with laboratory-confirmed MDR-TB was conducted in five TB designated hospitals. The population PK model for linezolid was built using nonlinear mixed-effects modeling using data from 168 participants. Boosted classification and regression tree analyses (CART) were used to identify the ratio of 0- to 24-h area under the concentration-time curve (AUC_0-24h) to the minimal inhibitory concentration (MIC) threshold using the BACTEC MGIT 960 method associated with successful treatment outcome and validated in multivariate analysis using data from a different and prospective cohort of 159 participants with MDR-TB. Furthermore, based on the identified thresholds, the recommended doses were evaluated by the probability of target attainment (PTA) analysis. Result: Linezolid plasma concentrations (1008 samples) from 168 subjects treated with linezolid, were best described by a 2-compartment model with first-order absorption and elimination. An AUC_0-24h/MIC > 125 was identified as a threshold for successful treatment outcome. Median time to sputum culture conversion between the group with AUC_0-24h/MIC above and below 125 was 2 versus 24 months; adjusted hazard ratio (aHR), 21.7; 95% confidence interval (CI), (6.4, 72.8). The boosted CART-derived threshold and its relevance to the final treatment outcome was comparable to the previously suggested target of AUC_0-24h/MIC (119) using MGIT MICs in a hollow fiber infection model. Based on the threshold from the present study, at a standard linezolid dose of 600 mg daily, PTA was simulated to achieve 100% at MGIT MICs of ≤ .25 mg which included the majority (81.1%) of isolates in the study. Conclusion: We validated an AUC_0-24h/MIC threshold which may serve as a target for dose adjustment to improve efficacy of linezolid in a bedaquiline-containing treatment. Linezolid exposures with the WHO-recommended dose (600 mg daily) was sufficient for all the M. tb isolates with MIC ≤ .25 mg/L.

Delamanid-containing regimens and multidrug-resistant tuberculosis: A systematic review and meta-analysis

INTRODUCTION

Multidrug-resistant tuberculosis (MDR-TB) is a life-threatening condition needing long poly-chemotherapy regimens. As no systematic reviews/meta-analysis is available to comprehensively evaluate the role of delamanid (DLM), we evaluated its effectiveness and safety.

METHODS

We reviewed the relevant scientific literature published up to January 20, 2022. The pooled success treatment rate with 95% confidence intervals (CI) was assessed using a random-effect model. We assessed studies for quality and bias, and considered P<0.05 to be statistically significant.

RESULTS

After reviewing 626 records, we identified 25 studies that met the inclusion criteria, 22 observational and 3 experimental, with 1276 and 411 patients, respectively. In observational studies the overall pooled treatment success rate of DLM-containing regimens was 80.9% (95% CI 72.6-87.2) with no evidence of publication bias (Begg's test; P >0.05). The overall pooled treatment success rate in DLM and bedaquiline-containing regimens was 75.2% (95% CI 68.1-81.1) with no evidence of publication bias (Begg's test; P >0.05). In experimental studies the pooled treatment success rate of DLM-containing regimens was 72.5 (95% CI 44.2-89.8, P <0.001, I²: 95.1%) with no evidence of publication bias (Begg's test; P >0.05).

CONCLUSIONS

In MDR-TB patients receiving DLM, culture conversion and treatment success rates were high despite extensive resistance with limited adverse events.

Synthesis and in vitro studies for structure-based design of novel chalcones as antitubercular agents targeting InhA

Background: The authors aimed to estimate the therapeutic potential of novel chalcones against tuberculosis. Methods: 11 synthesized compounds were tested for in vitro antimycobacterial activity against Mycobacterium tuberculosis (H37RV; American Type Culture Collection number: 27294) using the microplate alamarBlue assay. Molecular docking and pharmacokinetic parameter analyses were then performed. Results: The most potent compounds, (2E)-1-(4-bromophenyl) (2E)-1-(2-nitrophenyl) prop-2-en-1-one, -3-(2-nitrophenyl) prop-2-en-1-one (4-bromophenyl) (2E)-1-(3-phenoxyphenyl)prop-2-en-1-one, 3-(phenoxyphenyl)prop-2-en-1-one (4-bromophenyl) prop-2-en-1-one and (2E)-1-(4-bromophenyl)-3-(5-chloro-2-hydroxyphenyl)-prop-2-en-1-one, showed in vitro activity, with a minimum inhibitory concentration (MIC) of 6.25 μg/ml. Conclusion: Compounds LSD2, LSD12, LSD13 and LSD15 showed strong in vitro antimycobacterial activity at a concentration of 6.25 μg/ml.