Resistant Tuberculosis Research Articles

Development and preliminary assessment of the iFIND TBR: all-in- one molecular diagnostic assay for rapid detection of Mycobacterium tuberculosis and rifampicin resistance

IntroductionEarly and accurate diagnosis of tuberculosis (TB) is crucial for initiating timely treatment and preventing new infections. In this study, we introduced the iFIND TBR assay, an automated all-in-one tuberculosis detection approach that simultaneously detect Mycobacterium tuberculosis (MTB) and rifampicin (RIF) resistance.MethodsThe limits of detection (LOD), sensitivity, specificity, and RIF-R rpoB mutation detection of the iFIND TBR were tested on Mycobacterium tuberculosis DNA or sputum samples spiked with known numbers of M.tuberculosis H37Rv. Frozen clinical samples from patients suspected of having TB were also tested.ResultsThe LOD of the iFIND TBR for MTB detection were 13.34 CFU/ml (95% CI, 11.71-16.47), and for RIF resistance was 109.79CFU/mL (95% CI, 95-138.19). The iFIND TBR assay accurately distinguish MTB strains from non-tuberculous mycobacteria (NTM) without any cross reactivity. Testing on 157 clinical sputum samples, compared with the bacteriologically TB standard, the overall sensitivity and specificity of the iFIND TBR was 100% (95%CI, 94.64, 100) and 85.29% (95% CI, 74.61, 92.72), respectively. When assessing RIF susceptibility, the iFIND TBR achieved a sensitivity of 98.15% (95% CI, 90.11–99.95) and a specificity of 85.71% (95% CI, 67.33–95.97), compared with phenotypic drug susceptibility testing. Discordant RIF susceptibility results were more frequently observed in samples exhibiting heteroresistance.DiscussionThese findings demonstrate that iFIND TBR assay performs well in detecting TB and RIF resistance, and shows promise as a point-of-care tool in resource-limited areas.

A Rare Case of Tremor Induces by Cycloserine in Drug-Resistant Tuberculosis Patient

Background: Tuberculosis is a contagious disease that generated by Mycobacterium tuberculosis. Drug-Resistant tuberculosis (DR-TB) is inculpated the use of the second-line anti-tubercular treatment which is associated with many drug side effects or so called, Adverse Drug Reactions (ADR). Cycloserine (Cs) is an important drug against drug resistant tuberculosis (DR-TB). Cycloserine has been used in tuberculosis therapy since the late 1950s. Identical with most drug, Cycloserine can cause many Adverse Drug Reactions (ADR). Case Illustration: A 23-year-old woman diagnosed with drug-resistant tuberculosis is undergoing long-term treatment. The patient received treatment for DR-TB with the Bdq-Lfx-Cfz-Cs-E regimen. After the patient underwent the 10th month of advanced phase treatment, the patient complained of shaking in both hands (tremors). The tremor is felt to be more severe in the right hand and the patient cannot grip objects tightly. Discussion: Cycloserine (Cs) play an important role in second-line drug management of DR-TB. Cs-Induced psychosis and other neurological side-effects can be detrimental towards patients yet they are rarely reports in DR-TB cases. Cs is correlated with severe psychiatric cases and Central Nervous System related ADRs. Cs-associated ADR is most likely because of production of gamma-aminobutyric acid as a result of inhibition of glutamic decarboxylase. Study Shown that among 132 patients who reported side effects in the cycloserine group, 2 (1.4%) experienced major side effects, namely tremors. Side effects possibly or probably related to Cs appeared after a median of 71 days (range 10–331 days) of Cs treatment. Conclusion: the drug side effects such as tremors are very rare in drug-resistant tuberculosis patients. In this case, the patient's complaint of tremors could be caused by cycloserine as an anti-tuberculosis drug.

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.

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.

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.

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.

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.

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.

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

Genome sequencing analysis of the pncA, rpsA and panD genes responsible for pyrazinamide resistance of Mycobacterium tuberculosis from Indonesian isolates.

Developing the most suitable treatment against tuberculosis based on resistance profiles is imperative to effectively cure tuberculosis patients. Whole-genome sequencing is a molecular method that allows for the rapid and cost-effective detection of mutations in multiple genes associated with anti-tuberculosis drug resistance. This sequencing approach addresses the limitations of culture-based methods, which may not apply to certain anti-TB drugs, such as pyrazinamide, because of their specific culture medium requirements, potentially leading to biased resistance culture results. Thirty-four M. tuberculosis isolates were subcultured on a Lowenstein-Jensen medium. The genome of these bacteria was subsequently isolated using cetyltrimethylammonium bromide. Genome sequencing was performed with Novaseq Illumina 6000 (Illumina), and the data were analysed using the GenTB and Mykrobe applications. We also conducted a de novo analysis to compare the two methods and performed mutation analysis of other genes encoding pyrazinamide resistance, namely rpsA and panD. The results revealed mutations in the pncA gene, which were identified based on the databases accessed through GenTB and Mykrobe. Two discrepancies between the drug susceptibility testing and sequencing results may suggest potential instability in the drug susceptibility testing culture, specifically concerning PZA. Meanwhile, the results of the de novo analysis showed the same result of pncA mutation to the GenTB or Mykrobe; meanwhile, there were silent mutations in rpsA in several isolates and a point mutation; no mutations were found in the panD gene. However, the mutations in the genes encoding pyrazinamide require further and in-depth study to understand their relationship to the phenotypic profile. Compared to the conventional culture method, the whole-genome sequencing method has advantages in determining anti-tuberculosis resistance profiles, especially in reduced time and bias.

Identifying risk factors for recurrent multidrug resistant tuberculosis based on patient’s record data from 2016 to 2021: retrospective study

Globally, the prevalence of multidrug-resistant tuberculosis (MDR-TB) has been increasing recently. This is a major public health concern, as MDR-TB is more difficult to treat and has poorer outcomes compared to drug-sensitive tuberculosis. The main objective of the study was to identify risk factors for recurrent multidrug-resistant tuberculosis, at Alert Specialized Hospital, Addis Ababa, by using different parametric shared frailty models. From January 2016 to December 2021, a retrospective study was conducted on MDR-TB patients at Alert Specialized Hospital in Addis Ababa. The data for the study were collected from the medical records of MDR-TB patients at the hospital during this time period. Gamma and inverse-Gaussian shared frailty models were used to analyze the dataset, with the exponential, Weibull, and lognormal distributions included as baseline hazard functions. The data were analyzed using R statistical software. The median recurrence time of the patients was 12 months, and 149 (34.3%) had recurrences. The clustering effect was statistically significant for multiple drug-resistant tuberculosis patients’ recurrence. According to the Weibull-Inverse-Gaussian model, factors that reduced time to MDR-TB recurrence included lower weight (ɸ = 0.944), smoking (ɸ = 0.045), alcohol use (ɸ = 0.631), hemoptysis (ɸ = 0.041), pneumonia (ɸ = 0.564), previous anti-TB treatment (ɸ = 0.106), rural residence (ɸ = 0.163), and chronic diseases like diabetes (ɸ = 0.442) were associated with faster recurrence. While, higher education (ɸ = 3.525) and age (ɸ = 1.021) extended time to recurrence. For weight increment, smokers and alcohol users, clinical complications of hemoptysis and pneumonia, patients with pulmonary disease who had a history of previous anti-TB treatment, and being rural residents are prognostic factors. There was a significant clustering effect at the Alert Specialized Hospital in Addis Ababa, Ethiopia. The Weibull-Inverse Gaussian Shared Frailty Model was chosen as the best model for predicting the time to recurrence of MDR-TB.

Comparison of Truenat Mycobacterium tuberculosis with line probe assay for the diagnosis of rifampicin resistance and mutation pattern of Mycobacterium tuberculosis

Abstract Background: There is an increasing incidence of multidrug-resistant tuberculosis (TB)/preextensively drug-resistant TB (XDR TB) and XDR TB globally. Therefore, rapid diagnostic tests with good sensitivity and specificity are need of hour. Truenat Mycobacterium tuberculosis (MTB) is one such test which gives results in 1–2 h and can withstand a variety of environmental conditions. Objective: The objective of this study was to compare Truenat MTB with line probe assay (LPA) for the diagnosis of rifampicin resistance and to study the mutation pattern of MTB. Materials and Methods: A comparative record-based study was carried out among 325 patients with multidrug-resistant TB. Sputum samples for pulmonary TB and appropriate site samples for extrapulmonary TB were obtained and tested with Truenat-MTB and LPA. A comparison between results obtained by Truenat-MTB and LPA was done. Based on first-line-LPA and second-line-LPA, gene mutation pattern was studied. Results: Males (69.2%) were more than females (30.8%). 30–49 (34.5%) years of age were most commonly affected. The sensitivity, specificity, positive predictive value, and negative predictive value of Truenat MTB compared to LPA were 82.86%, 93.45%, 60.41%, and 97.83%, respectively. The most common gene mutation observed was katG MUT1 in 59 cases. This was followed by rpoB MUT1 in three cases, rpoB MUT2A in two cases, rpoB MUT2B in four cases, and rpoB MUT3 in 12 cases. gyrA mutation was seen in nine cases among which gyrA MUT3A was seen in one case, gyrA MUT3B in one case, and gyrA MUT3C was seen in four cases. Two cases of rrs MUT1 were seen. Five cases of inhA MUT1 were seen. Conclusion: Truenat has been found to be economical, less time-consuming, giving fast results, and accurate in the diagnosis of DR-TB. The most common gene mutation observed was katG MUT1 in 59 cases.

Experience of Using Delamanid in the Treatment of Multiple Drug Resistant Tuberculosis

The objective: to evaluate treatment results in MDR TB patients when delamanid is added to the treatment regimen.Subjects and Methods. 91 patients with multiple drug resistant pulmonary tuberculosis were included in the study, of which 36 people (39.6%) were HIV positive. Patients were divided into four comparison groups depending on HIV status and inclusion of delamanid in the treatment regimen. Groups receiving delamanid included only patients in whom bedaquiline or linezolid had been discontinued due to adverse reactions.Results. The results of treatment of MDR TB when delamanid is added to the chemotherapy regimen during the intensive phase, indicate its high effectiveness and safety including HIV positive patients.

Detection of Rifampicin Resistance rpoB Gene Using GeneXpert MTB/RIF Assay in Pulmonary Tuberculosis Cases at Debre Tabor Comprehensive Specialized Hospital, Northwest Ethiopia.

Tuberculosis (TB) is a preventable and treatable disease leading to the second death globally. The evolution of drug resistance in Mycobacterium tuberculosis (MTB), particularly rifampicin resistance (RR), has hampered TB control efforts. Thus, this study aimed to provide information regarding the magnitude of MTB and rifampicin resistance among patients tested using the GeneXpert method. A retrospective analysis was carried out at DTCSH. The study included TB registration logbook data from all patients who visited the hospital and were tested for MTB with the Xpert MTB/RIF assay from 2017 to 2024. The laboratory-based data were entered, cleaned, and analyzed using SPSS version 26 software. Multilogistic regression analysis was employed, and a p value ≤ 0.05 was considered statistically significant. A total of 12,981 patient results were included, of which 8.9% (1160/12,981) were MTB-positive and 7.1% (82/1160) were RR. Individuals aged 15-29 years (AOR = 2.13; 95% CI = 1.55-2.93, p < 0.001), living in rural areas (AOR = 1.23; 95% CI = 1.08-1.41, p = 0.003), and HIV+ (AOR = 1.79; 95% CI = 1.48-2.33, p < 0.001) had a higher risk of developing tuberculosis. While RR was identified in 63.4% (52/82) of new, 24.4% (20/82) of re-treated, and 12.2% (10/82) of failed presumptive TB patients. In this study, MTB and RR trends were high. Productive age groups, rural populations, and HIV patients were at risk. To lessen the burden of this contagious and fatal disease, it is recommended to increase early diagnosis of drug-resistant TB and enhance infection control.

Effectiveness of new antituberculosis drugs in the treatment of children and adolescents with chemoresistant tuberculosis

BACKGROUND. There is a significant decrease the effectiveness of antituberculous (anti-TB) treatment on the background of multidrug and extensive drug resistance (MDR/XDR) of Mycobacterium tuberculosis. Therefore, in order to increase the effectiveness of treatment MDR-/XDR-TB a new antimycobacterial drugs such as bedaquiline (Bdq), delamanid (Dlm) and pretomanid have been introduced both for adults, children and adolescents in recent years. MATERIALS AND METHODS. On the basis of a retrospective cohort analysis of the data of patients' medical records the evaluation of the clinical effectiveness of chemotherapy with Bdq and Dlm was carried out. The main group: 40 children and adolescents with MDR-/XDR-TB of lungs, who received complex antimycobacterial therapy (AMBT) with Bdq and Dlm. The control group consisted of 27 patients who received complex AMBT without Bdq and Dlm. Age range – from 3 to 18 years. RESULTS AND DISCUSSION. On the background of AMBT during the first 3 months of treatment was established stopping bacterial secretion among all patients of main and control groups. However, in control group compare to main one stopping bacterial secretion was significant slowly (p&lt;0.05). At the stage of completion of the intensive phase of AMBT, the normalization of immunological indicators occurred in 29.6±2.8 % of control group and in 43.4±4.5 % of main one. A significant difference between the groups among the immunoregulatory index CD3+CD4+/CD3+CD8+, IgM and circulating immune complexes was obtained. Among children and adolescents of the main group positive dynamic of immunological changes were observed 1.5 times more often. Among all patients of main group the resolution of the infiltration, consolidation of the focus and the absence of decay cavities were ascertained at the end of the anti-TB course. Anti-TB treatment with the formation of small residual changes into lung tissue ended in 77.5 % patients of main group. In 12.5 % cases of control group destructions persisted and bacterial excretion resumed. A large residual changes such as multiple dense foci, fibrosis and residual decay cavities in control group were observed 2.3 times more often (51.9 % vs 22.5 %), p&lt;0.05, than in main one. Using Bdq and Dlm among children and adolescents with MDR-/XDR-TB significantly increased efficiency of complex treatment. Among main group (72.5 %) compare to control (33.3 %) one the results of treatment to be considered “cured” were 2.2 times more likely and 1.5 times less often – “completed” (27.5 % vs 51.8 % respectively). The success rate of treatment among children and adolescents who received Bdq and Dlm was 100.0 % and among patients without these new drugs – 85.2 %. CONCLUSIONS. The criteria used show that AMBT combined with Bdq and Dlm is 1.5-2.2 times more effective (according to a separate criterion) than AMBT without these drugs.

Rifampicin-resistant Tuberculosis and Associated Factors Among Pulmonary Tuberculosis Patients in Mahakali Provincial Hospital, Nepal

The study aims at assessing the prevalence of RR-TB and identify associated factors among pulmonary TB patients using GeneXpert MTB/RIF assay data from January to December 2023. Tuberculosis (TB) continues to pose a significant global health threat, with rifampicin-resistant (RR) strains presenting a formidable challenge to disease control efforts. This study based the retrospective cross-sectional study conducted at Mahakali Provincial Hospital in Nepal. Out of 2587 presumptive TB cases, 11.8% were confirmed positive for TB, with males constituting a significantly higher proportion (66.1%) than females (33.9%). Among TB-positive cases, 3% showed resistance to rifampicin, predominantly affecting males (77.8%). Age group analysis revealed higher TB detection rates in the 46-60 years group, while rifampin -resistance tuberculosis (RR-TB) cases were more evenly distributed across age groups without statistical significance. Ethnicity and residential locality did not show significant associations with RR-TB. Multivariate logistic regression highlighted gender as RR-TB and associated factors among pulmonary tuberculosis patients in a Mahakali Provincial Hospital, Nepal. Rifampicin-resistant TB (RR-TB) remains a significant challenge at Mahakali Provincial Hospital, with a 3% prevalence, predominantly affecting males. Gender is a key factor in RR-TB prevalence. To manage and reduce RR-TB effectively, it is necessary to implement targeted interventions for high-risk groups, particularly males, and to enhance diagnostic capabilities.

Eco-friendly Biosynthesis of Silver Nanoparticles Using Elephantorrhiza elephantina: Characterization and Antimicrobial Activity against Mycobacterium tuberculosis Surrogate Models

The emergence of multidrug-resistant (MDR) and extensively-drug resistant (XDR) Mycobacterium tuberculosis (MTB) strains have scampered efforts to arrest the tuberculosis (TB) pandemic due to treatment failures based on current drugs. The need for novel therapeutics has never been more urgent. Research is leaning towards alternative composite antimicrobials such as silver nanoparticles (AgNPs). Elephantorrhiza elephantina (E. elephantina) is an indigenous Southern African rhizomatous plant which has been used for eons in African traditional medicine for the management of TB. The purpose of this study was to biosynthesize and characterize AgNps using E. elephantina, and to evaluate their antimicrobial effectiveness against surrogate MTB species. The study also sought to screen for the participating secondary metabolites in E. elephantina acting as bio reducing, capping and stabilising agents; and to determine the toxicity of the lyophilised root extract in vivo. Qualitative phytochemical screening techniques confirmed the presence of bioactive secondary metabolites with functional groups capable of mediating in the biosynthesis of AgNPs. UV-Vis spectrometry established the identity of the nanostructures as AgNPs. Transmission electron microscopy and dynamic light scattering confirmed the AgNPs to have an average size of 44 nm, with spherical and cubic morphologies. The biosynthesised AgNPs were potent inhibitors of the model MTB species with an MIC of 19.53 µg/mL, and inhibition zones of 20mm and 18mm against Mycolicibacterium aurum and Mycolicibacterium smegmatis respectively at their MICs. Oral toxicity evaluations based on OECD guideline 425 determined the LD50 of the lyophilised E. elephantina root extract to be safe above 4000mg/kg body weight. The study concluded that biosynthesized AgNPs from E. elephantina root extract, using a one-pot green-synthesis technique, were both safe and effective, offering a promising alternative therapeutic strategy for combating multidrug-resistant TB.

Widespread loss-of-function mutations implicating preexisting resistance to new or repurposed anti-tuberculosis drugs

BackgroundFive New or Repurposed Drugs (NRDs) were approved in the last decade for treatment of multi-drug resistant tuberculosis: bedaquiline, clofazimine, linezolid, delamanid, and pretomanid. Unfortunately, resistance to these drugs emerged faster than anticipated, potentially due to preexisting resistance in naïve strains. Previous investigations into the rapid emergence have mostly included short variants. For the first time, we utilize de novo-assembled genomes, and systematically include Structural Variations (SV) and heterogeneity to comprehensively study this rapid emergence. We show high prevalence of preexisting resistance, identify novel markers of resistance, and lay the foundation for preventing preexisting resistance in future drug development. MethodsFirst, a systematic literature review revealed 313 NRD resistance variants in 13 genes. Next, 409 globally diverse clinical isolates collected prior to the drugs’ programmatic use (308 were multidrug resistant, 106 had de novo assembled genomes) were utilized to study the 13 genes comprehensively for conventional, structural, and heterogeneous variants. FindingsWe identified 5 previously reported and 67 novel putative NRD resistance variants. These variants were 2 promoter mutations (in 8/409 isolates), 13 frameshifts (21/409), 6 SVs (9/409), 35 heterogeneous frameshifts (32/409) and 11 heterogeneous SVs (12/106). Delamanid and pretomanid resistance mutations were most prevalent (48/409), while linezolid resistance mutations were least prevalent (8/409). InterpretationPreexisting mutations implicated in resistance to at least one NRD was highly prevalent (85/409, 21 %). This was mostly caused by loss-of-function mutations in genes responsible for prodrug activation and efflux pump regulation. These preexisting mutations may have emerged through a bet-hedging strategy, or through cross-resistance with non-tuberculosis drugs such as metronidazole. Future drugs that could be resisted through loss-of-function in non-essential genes may suffer from preexisting resistance. The methods used here for comprehensive preexisting resistance assessment (especially SVs and heterogeneity) may mitigate this risk during early-stage drug development.

Cartridge-Based Nucleic Acid Amplification Test Compared to Fine Needle Aspiration Cytology in Suspected Cases of Tubercular Lymphadenitis (the Indian Experience)

INTRODUCTION: Diagnosis of tubercular lymphadenitis is daunting as there are varied clinical presentations and no single confirmatory gold standard test. Cartridge-based nucleic acid amplification test (CBNAAT) of the lymph node is a rapid molecular diagnostic test for simultaneously detecting tuberculosis (TB) and rifampicin resistance. AIM: To evaluate the performance of the CBNAAT test for detecting M. tuberculosis in lymph node specimens compared to fine needle aspiration cytology (FNAC). MATERIALS AND METHODS: The study was conducted in a rural tertiary care hospital in central India. A total of 180 patients clinically suspected of tubercular lymphadenitis were included. The male-to-female ratio was 1:1.3. The average age was 33.3 years. The age group 21–40 years had the highest number of cases. The most common complaints among the patients were fever (29.4%), followed by loss of appetite (9.5%), weight loss (9.5%), and cough (6.6%). However, most patients presented to the hospital with only lymphadenopathy (44.4%). The most common site involved was the anterior cervical lymph node (78.8%), followed by the axillary group (10.5%), submandibular (2.8%), inguinal (2.8%), supraclavicular (2.2%), submental (1.7%) and infraclavicular (1.1%) group of lymph nodes. The patients were subjected to both FNAC and CBNAAT testing. Results were reported as positive or negative for M. tuberculosis as CBNAAT gives a semiquantitative estimate of the concentration of bacilli. Rifampicin resistance results were reported as detected or not detected. RESULTS: Cytological examination of the lymph node aspirates revealed that most were tubercular lymphadenitis cases. Cytomorphological analysis of the cases of tubercular lymphadenitis revealed Type 6 (tubercular abscess) as the predominant pattern. CBNAAT testing detected 26 cases of M. tuberculosis and three cases of rifampicin resistance. The study reported a specificity of 92.92% and low sensitivity of 26.86% of combined FNAC and CBNAAT is much higher compared to only CBNAAT. CONCLUSION: CBNAAT, along with FNAC, is a valuable addition in first-line investigations of tubercular lymphadenitis to make a timely diagnosis.

Benzyl/phenyl‐1,2,3‐Triazole Tethered 3‐Acetyl Coumarins as Potential Drug‐Resistant Antitubercular Agents: Synthesis, Biology, and in Silico Investigations as Mtb DNA Gyrase Inhibitors

AbstractOwing to the emergence of multi‐drug resistant tuberculosis, there is a need for the exploration of new antitubercular agents. In this context, new coumarin‐based 1,2,3‐triazole hybrids were developed and evaluated for their antimicrobial activity against ESKAPE pathogens and the Mtb H37Rv strain. Among them, compounds 9 c and 12 showed MICs of 1 and 2 μg/mL, respectively, against the Mtb strain. The lead compounds exhibited a good selectivity index against Vero cells and were equally effective against ETB‐resistant and RIF‐resistant Mtb strains. Time‐kill kinetic studies revealed the bacteriostatic properties of the lead compounds, while combination studies using FDA‐approved antibiotics showed no drug interactions. Based on the structural similarity, it was envisaged that they might inhibit the DNA gyrase, which was further proved by the DNA supercoiling inhibition assay. Additionally, in silico docking studies, binding energy calculations, and ADME/T studies for the synthesized conjugates showed favourable pharmacokinetic and physicochemical characteristics. Hence, these molecules could further pave the way for discovering new potent antitubercular agents to combat AMR.