Multidrug-resistant Tuberculosis Research Articles

Prevalence of rifampicin and isoniazid mono-resistance among cases of pulmonary tuberculosis from Western Uttar Pradesh, North India.

Mono-resistance to rifampicin/isoniazid increases poor treatment outcomes and the risk of multi-drug resistance (MDR) in tuberculosis (TB) patients. Limited information exists about mono-resistance status of TB patients in Uttar Pradesh, North India. This study aimed to estimate the burden of rifampicin and isoniazid mono-resistance in Western Uttar Pradesh. 153 sputum samples of suspected pulmonary tuberculosis patients were processed to isolate Mycobacterium tuberculosis using the Lowenstein-Jensen (L-J) culture medium. The isolates were identified using an immuno-chromatographic test and IS6110 PCR. The confirmed Mycobacterium tuberculosis isolates were tested for drug susceptibility testing against rifampicin and isoniazid anti-tuberculosis drugs. The results of the drug susceptibility testing were compared with demographic information and analyzed statistically. Out of 153 sputum samples, 83 (54.24%) samples were positive for growth on L-J medium, including 82 (98.79%) Mycobacterium tuberculosis isolates. Of the 82 Mycobacterium tuberculosis isolates, 16 (19.51%), 7 (8.54%), and 5 (6.10%) isolates were MDR, mono-resistant to rifampicin and isoniazid, respectively. The occurrence of RIF/INH mono-resistant-TB was higher in patients of male gender, age above 45 years, living in rural conditions, history of weight loss, and previous anti-TB treatment, but the effect was not statistically significant. The study reported the status of rifampicin and isoniazid mono-resistance among TB patients and highlighted the need for continuous monitoring and improved intervention for the initial detection of mono-drug-resistant cases. This will improve clinical treatment outcomes and decrease the rate of drug-resistant TB in Uttar Pradesh, North India.

Multidrug-resistant tuberculosis treatment outcomes and associated factors at Yirgalem General Hospital, Sidama Region, South Ethiopia: a retrospective cohort study

BackgroundThe spread of multidrug-resistant tuberculosis (MDR-TB) poses a significant challenge to TB control efforts. This study evaluated the treatment outcomes and associated factors among patients receiving treatment for MDR-TB in southern Ethiopia.MethodsA retrospective follow-up study covering ten years, from 2014 to 2023, analyzed the records of confirmed cases of pulmonary TB admitted to Yirgalem General Hospital, an MDR-TB treatment initiation center in the Sidama Region. To compare the successful treatment outcomes across the years, a chi-square test of independence was conducted. Bivariate and multivariable logistic regression models were used to identify factors associated with treatment outcomes for MDR-TB.ResultsOut of 276 confirmed MDR-TB cases, 4(1.4%) were diagnosed with resistance to second-line drugs (SLDs). Overall, 138 patients achieved favourable treatment outcomes, resulting in a treatment success rate of 50.0% [95% CI 44.1–55.9%]. Among these 138 patients, 105(76.1%, 95 CI 68.7–83.5%) were cured, while 33(23.9%, 95 CI 16.5–31.3%) completed their treatment. The successful treatment outcomes varied significantly across the years, ranging from 3.6% in 2020 to 90% in 2021. The analysis indicated a statistically significant difference in treatment outcomes when considering data from 2014 to 2023 (χ2 = 44.539, p = 0.001). The proportion of patients with deaths, lost-to-follow-up (LTFU), treatment failures and not evaluated were 7.9% [95% CI 4.8–11.2%], 10.9% [95% CI 7.2–14.6%), 2.2% [95% CI 1.1–3.3%), and 28.9% [95% CI 23.7–34.2%] respectively. Individuals with a positive HIV status had significantly lower odds of a favorable treatment outcome [AOR = 0.628, 95% CI (0.479–0.824), p = 0.018]. Similarly, patients with a BMI of less than 18 are more likely to have unfavorable treatment outcomes compared to those with a BMI of 18 or higher [AOR = 2.353, 95% CI 1.404–3.942, p < 0.001].ConclusionThe study revealed a concerning 1.4% prevalence of additional resistance to SLDs. The 50% rate of unfavorable treatment among MDR-TB cases exceeds the target set by the WHO. A significant number of patients (10.9%) were LTFU, and the 28.9% categorized as ‘not evaluated’ is also concerning. Enhanced strategic interventions are needed to reduce such cases, and factors associated with poor treatment outcomes should receive greater attention. Future prospective studies can further explore the factors influencing improved treatment success.

Formation of treatment regimens in newly diagnosed patients before the diagnosis of pulmonary tuberculosis verification

Abstract. One of the basic principles of treatment of tuberculosis patients is the appointment of treatment taking into account the drug resistance of Mycobacterium tuberculosis (MBT). However, during treatment, it may be necessary to change the intake regimen when new data on drug resistance become available. The search for ways to choose the optimal treatment method seems relevant.Aim: To analyze the prescribed regimens and the reason for their correction in newly identified patients before verifying the diagnosis of tuberculosis.Material and Methods. The following methods were used to detect MBT: luminescent microscopy, molecular genetic methods and seeding on liquid and solid media. Tests for drug sensitivity were conducted in parallel. The study group consisted of patients with established bacterial excretion (n = 79), whose diagnosis was confirmed by cultural methods. A retrospective method was used in the analysis.Results. At the beginning of treatment with bacterioscopy and polymerase chain reaction methods MBT was detected in 65/79 (82.2%) cases, the remaining 14 cases were detected only by culture methods. Forced change of the therapy regimen during treatment after receiving the results was in 25/79 (31.6%) cases, of which 1/25 (4%) with isoniazid resistance, 7/25 (28%) with multidrug-resistant tuberculosis, 17/25 (68%) with the pre-extensive drug resistance regimen. The latter was prescribed only after receiving results of tests for drug sensitivity on liquid and solid media after 1–3 months. The multidrug-resistant tuberculosis treatment regimen decreased after receiving data on resistance to fluoroquinolones in accordance with the seeding data, but the largest number of patients still remained on this regimen – 41/79 (51.9%). Among these patients a change in chemotherapy regimen from multidrug-resistant tuberculosis to pre-extensive drug resistance during the intensive phase of treatment occurred in 17/25 (68%).Conclusion. When prescribing a regimen, it is recommended to assess the risk of changing the regimen and, if there are predictors, apply a chemotherapy regimen before treatment.

Exploring gene mutations and multidrug resistance in Mycobacterium tuberculosis: a study from the Lung Hospital in Vietnam.

Drug-resistant tuberculosis not only diminishes treatment efficacy but also heightens the risk of transmission and mortality. Investigating Mycobacterium tuberculosis resistance to first-line antituberculosis drugs is essential to tackle a major global health challenge. Using Sanger sequencing, this study investigates gene mutations associated with multidrug resistance in drug-resistant M. tuberculosis strains. Among 30 samples, mutations were found in genes linked to first-line anti-tuberculosis drug resistance. Rifampicin resistance was observed in 46.67% of the samples, with the most frequent mutation in the rpoB gene at codon 450 (S450L) occurring in 23.33% of cases. Similarly, isoniazid resistance was found in 86.67% of samples, with 33.33% of cases indicating the katG gene mutation at codon 315 (S315T). Additionally, streptomycin resistance was present in 76.67% of samples, and 30% of these cases were mainly linked to the rpsL gene mutation at codon 43 (K43R). These findings illuminate the genetic mechanisms behind drug resistance in M. tuberculosis. By identifying specific genetic markers, this research enhances our ability to diagnose and treat drug-resistant Tuberculosis more accurately and efficiently.

Patient and provider costs of the new BPaL regimen for drug-resistant tuberculosis treatment in South Africa: A cost-effectiveness analysis.

Drug-resistant (DR) tuberculosis (TB) is typically characterized by resistance to a single or combination of first- and/or second-line anti-TB agents and commonly includes rifampicin-resistant (RR)-TB, multidrug-resistant (MDR)-TB, pre-extensively drug-resistant (pre-XDR)-TB and XDR-TB. Historically, all variations of DR-TB required treatment with second-line drugs which are less effective and more toxic than first-line options, have a longer treatment duration and are more expensive to both patients and providers. The World Health Organization (WHO) now recommends a new second-line 3-drug 6-month all-oral regimen consisting of bedaquiline, pretomanid, and linezolid referred to as BPaL. We estimate patient and provider costs of DR-TB treatment with BPaL compared to the current standard of care in South Africa. In coordination with South Africa's BPaL clinical access programme (CAP) we conducted an economic evaluation of A) patient costs through a cross-sectional patient cost survey and B) provider costs through a bottom-up costing analysis consisting of a retrospective medical record review (patient resource-use) and top-down financial record review (fixed/shared costs such as overhead). Across both costing perspectives, we compare costs of 1) BPaL, to current standard of care options including the 2) 9-11-month standard short oral regimen (SSOR) and 3) 18-21-month standard long oral regimen (SLOR). Eligible patients included those ≥14 years old with confirmed sputum pulmonary RR/MDR-TB, pre-XDR or XDR-TB. All costs are reported in 2022 United States Dollar (US$). A total of 72 patients were enrolled and completed the patient cost survey (41.7% on BPaL, 16.7% on the SSOR and 41.7% on the SLOR). Mean on-treatment patient costs were lowest among those on BPaL ($56.6) and increased four-fold among those on the SSOR ($228.1) and SLOR ($224.7). Direct medical patient costs were negligible across all treatment regimens, while direct non-medical patient and guardian costs for travel, food and nutritional supplementation accounted for the largest proportion of total costs ($54.6, $227.8 and $224.3 for BPaL, the SSOR and SLOR respectively). In assessing provider costs, a total of 112 medical records were reviewed (37.5%, 41.1% and 21.4% on BPaL, the SSOR and SLOR respectively). Total provider costs for producing a favorable treatment outcome (cured/completed treatment) were similar among those on BPaL ($4,948.7 per patient) and the SSOR ($4,905.6 per patient) with costs increasing substantially among those on the SLOR ($8,919.9 per patient). Based on incremental cost-effectiveness ratios (ICERs), at even the lowest willingness to pay (WTP) threshold, treatment with the new BPaL regimen was more cost-effective than current standard of care treatment options (ICER: $311.4 < WTP: $3,341). When using the newly recommended BPaL regimen, cost to patients decreased by 75% compared to current standard of care treatment options in South Africa. Due in part to higher resource-use within the BPaL CAP offsetting the shorter treatment duration, cost of treatment provision through BPaL and the 9-11-month SSOR were similar. However, when considering cost and treatment outcomes, BPaL was more cost-effective than other standard of care regimens currently available for DR-TB in South Africa.

Silicosis predicts drug resistance and retreatment among tuberculosis patients in India: a secondary data analysis from Khambhat, Gujarat (2006–2022)

BackgroundIndia, with the highest global burden of tuberculosis (TB) and drug-resistant TB, aims to eliminate TB by 2025. Yet, limited evidence exists on drug resistance patterns and retreatment among patients with silico-tuberculosis. This study explores these patterns and assesses the impact of silicosis on TB retreatment in India.MethodsThis secondary data analysis stems from a larger retrospective cohort study conducted in Khambhat, Gujarat, between January 2006 and February 2022. It included 138 patients with silico-tuberculosis and 2,610 TB patients without silicosis. Data from the Nikshay TB information portal were linked with silicosis diagnosis reports from the Pneumoconiosis Board using the unique Nikshay ID as the linking variable. Drug-resistant TB was defined as resistance to any anti-TB drug recorded in Nikshay. Retreatment refers to TB patients who have previously undergone anti-TB treatment for one month or more and need further treatment. Recurrent TB denotes patients who were previously declared cured or had completed treatment but later tested positive for microbiologically confirmed TB. Multivariable logistic regression was used to determine the impact of co-prevalent silicosis on drug resistance and retreatment.ResultsPatients with silico-tuberculosis showed a higher proportion of retreatment compared to those without silicosis (55% vs. 23%, p < 0.001). Notably, 28% of patients with silico-tuberculosis were recurrent TB cases, compared to 11% among those without silicosis. Regarding drug resistance, the silico-tuberculosis group exhibited a higher rate (6% vs. 3%), largely due to rifampicin resistance (5% vs. 2%, p = 0.022). Co-prevalent silicosis was associated with a 2.5 times greater risk of drug-resistant TB (adjusted OR 2.5, 95% CI, 1.1–5.3; p = 0.021). Additionally, patients with silico-tuberculosis had a fourfold increased risk of retreatment for TB (adjusted OR 4, 95% CI, 3–6; p < 0.001).ConclusionsCo-prevalent silicosis significantly elevates the risk of drug resistance, recurrence, and retreatment among TB patients in India. This study indicates a need for improved treatment protocols and suggests that future research should focus on randomized controlled trials to evaluate appropriate anti-TB regimen and duration of therapy for this high-risk group. Given India’s goal to eliminate TB by 2025, addressing the challenges posed by silico-tuberculosis is critical.

Linezolid Pharmacokinetic-Anemia Modeling in Children with Rifampicin-Resistant Tuberculosis.

Linezolid, an important component of rifampicin- and multidrug-resistant tuberculosis (RR/MDR-TB) treatment, is associated with treatment-limiting toxicities, including anemia. Patient-level and linezolid pharmacokinetic risk factors for anemia have not been well described in children treated for RR/MDR-TB. We evaluated the pharmacokinetics of linezolid and longitudinal hemoglobin data to validate an existing population linezolid pharmacokinetic model. We assessed the impact of linezolid pharmacokinetics and the risk of developing anemia in a prospectively enrolled cohort of children. The validation of a previously published population pharmacokinetic linezolid model used nonlinear mixed effects modeling. A multivariable ordinal logistic regression model was built to predict the incidence of anemia. A total of 112 children, median age 7.2 (IQR: 2.2-16.3) years, were included from South Africa (n=87) and India (n=25). Of these, 24 children contributed new linezolid pharmacokinetic data. The population pharmacokinetic model which informs the currently recommended linezolid dosing in children (10-15 mg/kg) was validated with these additional new data. For every 1 g/dL lower baseline hemoglobin, the odds of developing grade 3 or 4 anemia increased by 2.64 (95% CI 1.98-3.62). For every 1 mg/L*h higher linezolid area under the concentration-time curve (AUC), the odds of developing a grade 3 or 4 anemia increased by 1.012 (95% CI 1.007-1.017). These data taken together, confirm currently recommended linezolid doses in children. The risk of anemia in children should be carefully considered and monitored throughout. Initiating linezolid in children with low baseline hemoglobin increases the probability of experiencing grade 3 or 4 anemia.

Management implications of latent TB among under-five children at risk: Insights from a community study in Mumbai, India.

Latent tuberculosis infection (LTBI) management is crucial to WHO's End TB Strategy. Indian guidelines recommend treating under-five children with household TB contacts after ruling out active TB, regardless of TBI testing. However, the precise LTBI burden among children in high TB burden settings like India is unknown. A community-based study in Mumbai's urban slums screened and managed under-five children at LTBI risk to understand its epidemiology and inform TB control interventions. Total 369 eligible under-five children were enrolled for the study. LTBI screening was done using Tuberculin skin test and Interferon gamma release assay. Active TB was ruled out before initiation of TB preventive therapy among LTBI positives. Statistical tests like chi-square, logistic regression analysis and Hosmer-Lemeshow test were used. Overall, LTBI prevalence among under-five children was 12.4% by IGRA and 21.4% by TST. Undernourished children had significantly lower LTBI positivity by IGRA (p = 0.027), while those with household contacts, longer contact duration and drug-resistant tuberculosis (DR-TB) exhibited proportionally greater IGRA positivity (p = <0.001). The study found a lower LTBI prevalence among under-five children compared to adults, with key risk factors being HHC, DR-TB contact, and prolonged exposure. These findings suggest the need to revise or revisit the TPT framework for this age group in India, particularly by implementing a test-and-treat approach.

Draft genome sequence of Mycolicibacterium conceptionense isolated from the sputum sample of a patient with pulmonary tuberculosis.

We report the draft genome of Mycolicibacterium conceptionense, a rapidly growing nontuberculous mycobacterium, isolated from the sputum sample of a patient undergoing treatment for multidrug-resistant tuberculosis in Delhi, India. The 6,366,717-bp genome contains 6,124 coding sequences, one 5S rRNA, three 16S rRNAs, six 23S rRNAs, and 49 tRNAs.

A non-randomized pragmatic historically controlled trial evaluating the effectiveness and safety of a bedaquiline or a linezolid-based short regimen for rifampicin-resistant tuberculosis

Short all-oral regimens for Rifampicin-resistant tuberculosis (ShORRT) have been a turning point in the treatment of drug-resistant tuberculosis. Despite this, access to drugs, stockouts, or adverse effects may limit the use of the recommended regimens. Pragmatic non-randomized trial evaluating the efficacy and safety of a ShORRT strategy for the treatment of rifampicin-resistant Tuberculosis (RR-TB) at the Hospital Nossa Senhora da Paz (Angola). The strategy assigned participants to receive a bedaquiline (BDQ) or a linezolid-based (LZF) regimen supplemented with levofloxacin, clofazimine, and cycloserine for up to 9 months. One hundred and twenty-one participants with pulmonary RR-TB were treated with the ShORRT strategy; 69 received the bedaquiline- and 52 the linezolid-based regimen. Overall, 98 (81%) participants had successful treatment outcomes, which was significantly higher compared to a 20-month historical injectable-based regimen (successful outcome rate including cure and treatment completed: 53.7%) (p<0.001). No significant differences between treatment success rates (85.5% vs. 75.0%), treatment failure (0.0% vs. 1.9%), death (5.8% vs. 13.5%), or lost to follow-up (LTFU) (8.7% vs. 9.6%) were seen between the BDQ and the LZF-based regimen. Globally, 72 adverse events (AE) occurred in 36 (29.7%) participants. Eighteen (14.9%) of these were grade ≥3 and were more frequently observed in those receiving the LZD-based regimen (p=0.02). The ShORRT strategy with a nine-month BDQ- or LZD-based regimen supports the efficacy of shorter all-oral regimens for the treatment of RR-TB and presents real-world data from schemes without bedaquiline, nitroimidazole, or injectables.

Prevalence and epidemic pattern of ecdemic multidrug-resistant tuberculosis during 2012–2022 in Hangzhou, China: implication for public health strategies

BackgroundTo assess the prevalence and epidemic pattern of multidrug-resistant tuberculosis in Hangzhou City, Zhejiang Province, China during 2012–2022.MethodsAll the tuberculosis cases undergoing drug susceptibility testing during 2012–2022 were included in this study. De-identified information was extracted from the electronic database Tuberculosis Information Management System for analysis of drug resistance prevalence in Hangzhou and ecdemic multidrug-resistant tuberculosis which originated from other regions. Chi-square tests were used to compare drug resistance rates between different groups, while Chi-square tests for trend were used to evaluate the change of drug resistance rates over the years of 2012–2022. The sources and destinations of ecdemic multidrug-resistant tuberculosis were illustrated using a Sankey diagram.ResultsOf 21,127 cases included in this study, 1119 (5.3%) were multidrug-resistant tuberculosis. A significant decline in multidrug-resistant tuberculosis rates was observed during 2012–2022. There was a significant difference in multidrug-resistant tuberculosis rates among immigrant population and local residents in Hangzhou City. Of 1119 multidrug-resistant tuberculosis cases, 515(46%) were ecdemic multidrug-resistant tuberculosis cases, of which 277(53.8%) were from other parts of Zhejiang Province and 238(46.2%) were from other provinces in China. Anhui, Jiangxi and Sichuan were among top three provinces which were the source of ecdemic multidrug-resistant tuberculosis cases. Three districts including Xiaoshan, Shangcheng and Linping districts had the most cases in Hangzhou. The proportion of ecdemic multidrug-resistant tuberculosis cases in Binjiang, Xiaoshan, Qiantang and Linping districtalso exceeded 30% of total cases.ConclusionsMultidrug-resistant tuberculosis prevalence has been declining in Hangzhou. Migrant population contributed to a significant potion of cases in Hangzhou. Interventions should be tailed to local and migrant residents.

Targeted next-generation sequencing - a promising approach in the diagnosis of Mycobacterium tuberculosis and drug resistance.

Targeted next-generation sequencing (tNGS) offers a high-throughput, culture-independent approach that delivers a comprehensive resistance profile in a significantly shorter turn-around time, making it promising in enhancing tuberculosis (TB) diagnosis and informing treatment decisions. This study aims to evaluate the performance of tNGS in the TB diagnosis and drug resistance detection of Mycobacterium tuberculosis (MTB) using MTB clinical isolates and bronchoalveolar lavage fluid (BALF) samples. A total of 143 MTB clinical isolates were assessed, tNGS, phenotypic antimicrobial susceptibility testing (AST), and AST based on whole genome sequencing (WGS) exhibited high concordance rates, averaging 95.10% and 97.05%. Among 158 BALF samples, culture, Xpert MTB/RIF, and tNGS reported 29, 70 and 111 positives, respectively. In the confirmed cases with etiological evidence (smears, cultures, or molecular test), the positive rate of tNGS (73/83, 87.95%) was higher than that of Xpert MTB (67/83, 80.72%). Additionally, 45% (27/60) of clinically diagnosed cases (with imaging or immunological evidence) were positive for tNGS. Further validation on the discrepant results between tNGS and Xpert MTB/RIF with droplet digital PCR (ddPCR) yielded 35 positives, tNGS detected all, and Xpert MTB/RIF only identified 6 positives. In conclusion, tNGS demonstrates robust and rapid performance in the identification of MTB and its associated drug resistance, and can be directly applied to clinical samples, positioning it as a promising approach for laboratory testing of tuberculosis.

Drug-induced liver injury associated with pretomanid, bedaquiline, and linezolid: Insights from FAERS database analysis.

The emergence of drug-resistant tuberculosis has necessitated novel treatments like the pretomanid, bedaquiline and linezolid (BPaL) regimen. This study investigated the association of drug-induced liver injury (DILI) with the BPaL regimen compared to first-line antituberculosis drugs (isoniazid, rifampin, pyrazinamide and ethambutol [HRZE]). A retrospective pharmacovigilance analysis was conducted using data from the US Food and Drug Administration Adverse Event Reporting System database from July 2019 to June 2023. Disproportionality analysis was employed to calculate the reporting odds ratio (ROR) of DILI for each component of the BPaL regimen. Onset time and mortality rates of DILI across different regimens were also compared. We identified 1242 cases of BPaL-related DILI. Most cases occurred in individuals under 65 years of age (63.8%), with more male patients affected than females (51.4% vs 39.5%). The association between antituberculosis drugs and DILI was stronger for the HRZE regimen (ROR = 7.99, 95% confidence interval [CI] 7.74-8.25) than the BPaL regimen (ROR = 4.75, 95% CI 4.55-4.97). The median onset time for DILI was significantly shorter with the BPaL regimen (8days, interquartile range [IQR] 3-28) compared to the HRZE regimen (20 days, IQR 6-48) (P < .001). Additionally, the BPaL regimen was associated with a higher risk of death due to DILI compared to the HRZE regimen (14.1% vs 10.4%, P = .003). Although the BPaL regimen had a lower overall risk of DILI compared to the HRZE regimen, it was significantly associated with DILI, indicating a need for careful monitoring during treatment.

Comparison of Molecular Testing Methods in Detecting Drug Resistance Tuberculosis

Tuberculosis (TB) is the leading cause of infectious disease-related deaths in Indonesia, and the COVID-19 pandemic has led to a decline in TB reporting and an increase in Drug-Resistant Tuberculosis (DR-TB). While traditional culture and Drug Susceptibility Testing (DST) takes 2-8 weeks, therefore, genotypic assays such as GeneXpert, Line Probe Assay (LPA), and sequencing offer faster and more precise diagnosis and drug resistance information.

Engineered Mycobacteriophage TM4::GeNL Rapidly Determines Bedaquiline, Pretomanid, Linezolid, Rifampicin, and Clofazimine Sensitivity in Mycobacterium tuberculosis Clinical Isolates.

Drug-resistant tuberculosis is a growing public health threat, and early characterization of the resistance phenotype is essential for guiding treatment and mitigating the high mortality associated with the disease. However, the slow growth rate of Mycobacterium tuberculosis, the causative agent of tuberculosis, necessitates several weeks for conventional culture-dependent drug susceptibility testing (DST). In addition, there are no widely available molecular diagnostic assays for evaluating resistance to newer tuberculosis drugs or drugs with complex resistance mechanisms. We have developed a luciferase-based reporter mycobacteriophage assay that can determine drug resistance within 48 hours. We engineered the TM4 mycobacteriophage to express green enhanced nanoluciferase (GeNL) cassette and optimized DST for bedaquiline, pretomanid, linezolid, clofazimine, and rifampicin using clinical M. tuberculosis isolates. To assess the feasibility of this assay, we conducted a proof-of-principle study using 53 clinical M. tuberculosis isolates. TM4::GeNL phage DST effectively distinguished between sensitive and resistant isolates for bedaquiline and rifampicin at a concentration of 0.125 μg/mL. Optimal differentiation between sensitive and resistant isolates for pretomanid, clofazimine, and linezolid was achieved at concentrations of 0.5 μg/mL, 0.25 μg/mL, and 1 μg/mL, respectively. Additionally, TM4::GeNL DST identified low-level rifampicin resistance in clinical isolates even though they were classified as sensitive by Mycobacteria Growth Indicator Tube DST. TM4::GeNL reporter phage DST offers a rapid method to identify M. tuberculosis drug resistance, including resistance to newer tuberculosis drugs.

Levofloxacin activity at increasing doses in a murine model of fluoroquinolone-susceptible and -resistant tuberculosis.

High-dose levofloxacin was explored in a clinical trial against multidrug-resistant tuberculosis and failed to show increased efficacy. In this study, we used a murine model to explore the efficacy of a dose increase in levofloxacin monotherapy beyond the maximum dose evaluated in humans. A total of 120 4-week-old female BALB/c mice were intravenously infected with 106 CFU of Mycobacterium tuberculosis H37Rv wild-type (WT) or isogenic H37Rv mutants harboring GyrA A90V or D94G substitutions; the MICs were 0.25, 4, and 6 µg/mL, respectively. Levofloxacin 250 and 500 mg/kg were given every 12 h (q12h) orally for 4 weeks. Pharmacokinetic parameters were determined after five doses. These two regimens decreased lung bacillary load in mice infected with H37Rv WT but not in mice infected with the A90V and D94G mutants. Levofloxacin 250 mg/kg q12h in mice generated pharmacokinetic parameters equivalent to 1,000 mg/d in humans, whereas 500 mg/kg q12h generated a twofold greater exposure than the highest equivalent dose tested in humans (1,500 mg/d). In our dose-response model, the effective concentration at 50% (EC50) produced an AUC/MIC (AUC0-24h/MIC) ratio of 167.9 ± 27.5, and at EC80 it was 281.2 ± 97.3. Based on this model, high-dose levofloxacin regimens above 1,000 mg/d are not expected to cause a significant increase in bactericidal activity. This study suggests no benefit of high-dose levofloxacin above 1,000 mg/d in the treatment of fluoroquinolone-susceptible or -resistant tuberculosis.

Immune Modulating Activty of a Biological Active Compound on the Cell Mediated and Humoral Immunity in Patients with Drug Sensible and Drug Resistant Pulmonary Tuberculosis

Immune Modulating Activty of a Biological Active Compound on the Cell Mediated and Humoral Immunity in Patients with Drug Sensible and Drug Resistant Pulmonary Tuberculosis

MOLECULAR GENETIC CHARACTERISTICS OF MYCOBACTERIUM TUBERCULOSIS ISOLATES CIRCULATING IN ASTANA

According to the World Health Organization, Kazakhstan takes a leading position in the number of cases of multidrug-resistant tuberculosis. This work is aimed at studying clinical isolates of Mycobacterium tuberculosis circulating in Astana in 2021–2022. Among 198 M. tuberculosis isolates collected, 175 (88.38%) belonged to the L2/Beijing family, and the remaining 23 samples (11.62%) belonged to the L4 family. During the research used genotyping aimed at determining the genetic family of M. tuberculosis, as well as whole-genome sequencing of selected 24 L2/Beijing isolates with their subsequent bioinformatics analysis. According to the analysis results, 62.5% of isolates were assigned to the Central Asia Outbreak genotype. The remaining genotypes were represented by Central Asia (20.8%), B0/W148 (12.5%) and Clade A (4.2%). Besides that, phenotypic and genotypic characterization of the resistance of selected isolates to anti-tuberculosis drugs was carried out. One of the possible reasons for the spread of resistant forms of tuberculosis in the country is the predominance of the Central Asia Outbreak genetic cluster associated with MDR-TB.

Impact of isoniazid monoresistance on overall and vulnerable patient populations in Taiwan

ABSTRACT Isoniazid is an early bactericidal anti-tuberculosis (TB) agent and isoniazid mono-resistance TB is the most prevalent drug-resistant TB worldwide. Concerns exist regarding whether resistance to isoniazid would lead to delayed culture conversion and worst outcomes. From January 2008 to November 2017, adult culture-positive pulmonary TB patients receiving isoniazid, rifampicin, pyrazinamide, and ethambutol were identified through Taiwan Center for Disease Control database and were followed until the end of 2017. Primary outcomes included time to sputum culture conversion (SCC) within two months. Secondary outcomes included death and unfavourable outcomes at the end of 2nd month. A total of 37,193 drug-susceptible and 2,832 isoniazid monoresistant pulmonary TB patients were identified. Compared with no resistance, isoniazid monoresistance was not associated with a delayed SCC (HR: 0.99, 95% CI: 0.94─1.05, p = 0.8145), a higher risk of 2-month mortality (HR: 1.19, 95% CI: 0.92─1.53, p = 0.1884), and unfavourable outcomes at 2nd month (OR: 1.05, 95% CI: 0.97─1.14, p = 0.2427). Isoniazid monoresistance was associated with delayed SCC (HR: 0.90, 95% CI: 0.83─0.98, p = 0.0099) and a higher risk of unfavourable outcomes (OR:1.18, 95% CI: 1.05─1.32, p = 0.0053) in patients aged between 20 and 65, and delayed SCC in patients without underlying comorbidities (HR: 0.90, 95% CI: 0.81─0.98, p = 0.0237). Isoniazid mono-resistant TB had a comparable outcome with drug-susceptible TB at the end of the intensive phase. Healthy, and non-elderly patients were more likely to had culture persistence, raising concerns about disease transmission in these subgroups and warranting early molecular testing for isoniazid resistance.

Study of Molecular Docking, Molecular Dynamics, Pharmacokinetics and Toxicity Prediction: Compounds from Nigella sativa Linn, Andrographis paniculata Nees, and Propolis as Inhibitors of Mycobacterium tuberculosis Growth

Background: Tuberculosis (TB) is caused by *Mycobacterium tuberculosis*, and Multiple Drug-Resistant Tuberculosis (MDR-TB) arises from resistance to first-line treatments like Rifampicin and Isoniazid. Since current TB medications have been used for over four decades, discovering new drug candidates is critical. This research focuses on herbal compounds—Black cumin (*Nigella sativa*), Sambiloto (*Andrographis paniculata*), and propolis—as potential inhibitors of *M. tuberculosis* by targeting DHFR. The objective of the study is to predict the activity of these herbal compounds prior to in vitro and in vivo testing. Methods: This study employed computational tools, including Molegro Virtual Docking (MVD) and Molecular Dynamics (MD), to assess the interactions of the herbal compounds with DHFR (PDB ID: 2CIG). Pharmacokinetic predictions were also conducted to evaluate the absorption and toxicity of the compounds. Results: Molecular docking and MD simulations indicated that Andrographolide, Thymoquinone, and Caffeic Acid Phenethyl Ester effectively inhibited the growth of *M. tuberculosis*. The analysis revealed favorable binding interactions and conformational changes in DHFR, with significant activity observed for Thymoquinone. Conclusion: This study suggests that Andrographolide, Thymoquinone, and Caffeic Acid Phenethyl Ester may serve as promising candidates for further development as anti-tuberculosis drugs. Subsequent in vitro and in vivo studies are warranted to validate their therapeutic potential.