Treatment Of Drug-resistant Tuberculosis Research Articles

Safety Profile of Medicines Used for the Treatment of Drug-Resistant Tuberculosis: A Descriptive Study Based on the WHO Database (VigiBase®).

The introduction of new drugs that increase the usage of repurposed medicines for managing drug-resistant tuberculosis (DR-TB) comes with challenges of understanding, properly managing, and predicting adverse drug reactions (ADRs). In addition to the health consequences of ADRs for the individual, ADRs can reduce treatment adherence, thus contributing to resistance. This study aimed to describe the magnitude and characteristics of DR-TB-related ADRs through an analysis of ADRs reported to the WHO database (VigiBase) in the period from January 2018 to December 2020. A descriptive analysis was performed on selected reports from VigiBase on the basis of medicine-potential ADR pairs. The ADRs were stratified by sex, age group, reporting country, seriousness, outcome of the reaction, and dechallenge and rechallenge. In total, 25 medicines reported to be suspected individual medicines or as a fixed-dose combination in the study period were included the study. Pyrazinamide (n = 836; 11.2%) was the most commonly reported medicine associated with ADRs, followed by ethionamide (n = 783; 10.5%) and cycloserine (n = 696; 9.3%). From the report included in this analysis, 2334 (31.2%) required complete withdrawal of the suspected medicine(s), followed by reduction of the dose (77; 1.0%) and an increased dose (4; 0.1%). Almost half of the reports were serious ADRs mainly caused by bedaquiline, delamanid, clofazimine, linezolid, and cycloserine that are the backbone of the DR-TB treatment currently in use. A third of the reports required medication withdrawal, which impacts treatment adherence and ultimately leads to drug resistance. Additionally, more than 40% of the reports indicated that ADRs appeared two months after the commencement of treatment, thus it's important to remain alert for the potential ADRs for the entire duration of the treatment.

Optimizing mycobacteria molecular diagnostics: No decontamination! Human DNA depletion? Greener storage at 4 °C!

Tuberculosis (TB) is an infectious disease caused by the group of bacterial pathogens Mycobacterium tuberculosis complex (MTBC) and is one of the leading causes of death worldwide. Timely diagnosis and treatment of drug-resistant TB is a key pillar of WHO's strategy to combat global TB. The time required to carry out drug susceptibility testing (DST) for MTBC via the classic culture method is in the range of weeks and such delays have a detrimental effect on treatment outcomes. Given that molecular testing is in the range of hours to 1 or 2 days its value in treating drug resistant TB cannot be overstated. When developing such tests, one wants to optimize each step so that tests are successful even when confronted with samples that have a low MTBC load or contain large amounts of host DNA. This could improve the performance of the popular rapid molecular tests, especially for samples with mycobacterial loads close to the limits of detection. Where optimizations could have a more significant impact is for tests based on targeted next generation sequencing (tNGS) which typically require higher quantities of DNA. This would be significant as tNGS can provide more comprehensive drug resistance profiles than the relatively limited resistance information provided by rapid tests. In this work we endeavor to optimize pre-treatment and extraction steps for molecular testing. We begin by choosing the best DNA extraction device by comparing the amount of DNA extracted by five commonly used devices from identical samples. Following this, the effect that decontamination and human DNA depletion have on extraction efficiency is explored. The best results were achieved (i.e., the lowest Ct values) when neither decontamination nor human DNA depletion were used. As expected, in all tested scenarios the addition of decontamination to our workflow substantially reduced the yield of DNA extracted. This illustrates that the standard TB laboratory practice of applying decontamination, although being vital for culture-based testing, can negatively impact the performance of molecular testing. As a complement to the above experiments, we also considered the best Mycobacterium tuberculosis DNA storage method to optimize molecular testing carried out in the near- to medium-term. Comparing Ct values following three-month storage at 4 °C and at -20 °C and showed little difference between the two. In summary, for molecular diagnostics aimed at mycobacteria this work highlights the importance of choosing the right DNA extraction device, indicates that decontamination causes significant loss of mycobacterial DNA, and shows that samples preserved for further molecular testing can be stored at 4 °C, just as well at -20 °C. Under our experimental settings, human DNA depletion gave no significant improvement in Ct values for the detection of MTBC.

Comparison of Hearing Thresholds among Patients on Treatment for Drug-Resistant Versus Drug-Susceptible Pulmonary Tuberculosis in A SubSaharan African Healthcare Setting

Background: Pulmonary tuberculosis is a debilitating infectious disease that affects all age groups and sadly, a leading cause of death in developing countries particularly in sub-Saharan Africa. One major challenge facing the global efforts against tuberculosis is drug-resistance, which necessitates the use of aminoglycoside-based second line drugs that are known to have ototoxic potentials. Hearing impairment can be a source of social distress, professional disability and in some cases, litigation. This research compared the pure tone audiometric patterns of patients on treatment for drug-resistant versus drug-susceptible pulmonary tuberculosis. The incidence of hearing loss between the groups was assessed. Patients and Method: The research was a prospective comparative study of all eligible newly diagnosed pulmonary tuberculosis patients admitted into the Pulmonology unit of Federal Medical Centre, Owerri, Nigeria. Pre-treatment (baseline) and monthly pure tone audiometry was done for each patient before and during treatment respectively. The patients were followed up and assessed for three months. Data collected was analyzed with Statistical Package for Social Sciences (SPSS) version 20.0 software for Windows. Statistical significance was set at p< 0.05. Results: A total of 76 patients (38 in each group) completed the study. The M:F ratio was 1.53:1 and 1.24:1 for the drug resistant and drug susceptible groups respectively while the mean duration of presenting symptoms were 11.7 ± 7.8 and 7.4 ± 5.1 weeks for the groups respectively. The prevalence of baseline hearing impairment was 73.7% among both groups while by the third month it was 89.5% among the dug-resistant group and 78.9% among the drug-susceptible group implying a cumulative incidence of hearing loss of 15.8% and 5.3% respectively over three months. This difference was statistically significant. Conclusion: The incidence of hearing impairment among patients on treatment for drug-resistant pulmonary tuberculosis was approximately three-fold higher than their drug susceptible counterparts after three months of treatment; this was statistically significant.

The socio-demographic, clinical characteristics and outcomes of tuberculosis among HIV infected adults in Lithuania: A thirteen-year analysis.

Tuberculosis (TB) is a public health problem in Lithuania, among the 18 high-priority TB countries in the European region, and the most common AIDS-indicative disease with the highest proportion in the EU/EEA since 2015. The study aimed to identify socio-demographic, clinical characteristics and their relationship with TB outcomes in TB-HIV co-infected patients in Lithuania. A retrospective chart review analysed the characteristics of TB-HIV co-infected adults registered in State Information System of Tuberculosis over 2008-2020. The factors associated with drug-resistant TB and unsuccessful treatment outcome were identified by multivariable logistic regression. The study included 345 cases in 311 patients (239 new, 106 previously treated cases), median age 40 years (IQR 35-45), 80.7% male. 67.8% patients knew their HIV-positive status before TB diagnosis, median time to TB diagnosis was 8 years (IQR 4-12). 83.6% were unemployed, 50.5%-anytime intravenous drug users (IDU), 34.9% abused alcohol. Drug-resistant TB rates in new and previously treated TB cases were 38.1% and 61.3%, respectively. In multivariable analysis, higher risk of drug-resistant TB was associated with imprisonment in new (aOR 3.35; 95%CI 1.17-9.57) and previously treated (aOR 6.63; 95%CI 1.09-40.35) cases. In 52.3% of new TB cases and in 42.5% previously treated TB cases the treatment outcomes were unsuccessful. In multivariable analysis of new TB cases, current imprisonment (aOR 2.77; 95%CI 1.29-5.91) and drug-resistant TB (aOR 2.18; 95%CI 1.11-4.28) were associated with unsuccessful treatment outcome. In multivariable analysis of previously treated TB cases, female gender (aOR 11.93; 95%CI 1.86-76.69), alcohol abuse (aOR 3.17; 95%CI 1.05-9.58), drug-resistant TB (aOR 4.83; 95%CI 1.53-15.28) were associated with unsuccessful treatment outcome. In the TB-HIV-infected adult cohort in Lithuania, unemployment, imprisonment, IDU, alcohol abuse, known to be risk factors for TB, were very frequent. Drug resistance was an undeniable risk factor for unsuccessful treatment outcome and imprisonment was associated with drug resistant TB.

Shorter regimens improved treatment outcomes of multidrug-resistant tuberculosis patients in Tanzania in 2018 cohort.

In 2018, shorter treatment regimens (STR) for people with drug-resistant tuberculosis (DR-TB) were introduced in Tanzania and included kanamycin, high-dose moxifloxacin, prothionamide, high-dose isoniazid, clofazimine, ethambutol and pyrazinamide. We describe treatment outcomes of people diagnosed with DR-TB in a cohort initiating treatment in 2018 in Tanzania. This was a retrospective cohort study conducted at the National Centre of Excellence and decentralised DR-TB treatment sites for the 2018 cohort followed from January 2018 to August 2020. We reviewed data from the National Tuberculosis and Leprosy Program DR-TB database to assess clinical and demographic information. The association between different DR-TB regimens and treatment outcome was assessed using logistic regression analysis. Treatment outcomes were described as treatment complete, cure, death, failure or lost to follow-up. A successful treatment outcome was assigned when the patient achieved treatment completion or cure. A total of 449 people were diagnosed with DR-TB of whom 382 had final treatment outcomes: 268 (70%) cured; 36 (9%) treatment completed; 16 (4%) lost to follow-up; 62 (16%) died. There was no treatment failure. The treatment success rate was 79% (304 patients). The 2018 DR-TB treatment cohort was initiated on the following regimens: 140 (46%) received STR, 90 (30%) received the standard longer regimen (SLR), 74 (24%) received a new drug regimen. Normal nutritional status at baseline [adjusted odds ratio (aOR)=6.57, 95% CI (3.33-12.94), p < 0.001] and the STR [aOR=2.67, 95% CI (1.38-5.18), p=0.004] were independently associated with successful DR-TB treatment outcome. The majority of DR-TB patients on STR in Tanzania achieved a better treatment outcome than on SLR. The acceptance and implementation of STR at decentralised sites promises greater treatment success. Assessing and improving nutritional status at baseline and introducing new shorter DR-TB treatment regimens may strengthen favourable treatment outcomes.

In vitro activity of tetracycline analogs against multidrug-resistant and extensive drug resistance clinical isolates of Mycobacterium tuberculosis

BackgroundMultidrug-resistant tuberculosis (MDR-TB) has become a big threaten to global health. The current strategy for treatment of MDR-TB and extensive drug resistant tuberculosis (XDR-TB) is with low efficacy and high side effect. While new drug is fundamental for cure MDR-TB, repurposing the Food and Drug Administration (FDA)-approved drugs represents an alternative soluation with less cost. MethodsThe activity of 8 tetracycline-class antibiotics against mycobacterium tuberculosis (M.tb) were determined by Minimum Inhibitory Concentration (MIC) in vitro. A transposon M.smeg libraries was generated by using the Harm phage and then used to isolate the conditional growth mutants in doxycycline containing plate. Eleven mutants were isolated and genomic DNAs were extracted using the cetyltrimethyl ammonium bromide (CTAB) method and analyzed by whole genome sequencing. ResultsWe found that three of eight drugs efficiently inhibited mycobacteria growth under the peak plasma concentration in the human body. Further tests showed these three tetracycline analogs (demeclocycline, doxycycline and methacycline) had antimicrobial activity against seven clinical isolates, including MDR and XDR strains. Among them, Doxycycline had the lowest MICs in all mycobacteria strains tested in this study. By using a transposon library, we identify the insertion of transposon in two genes, porin and MshA, associatewith the resistant to doxycycline. ConclusionsOur findings show that tetracycline analogs such as doxycycline, has bactericidal activity against not only drug sensitive M.tb, but also clinical MDR and XDR strains, provided proof of concept to repurpose doxycycline to fight MDR-TB and XDR-TB. Further investigations are warranted to clarify the underlying mechanism and optimize the strategy in combination with other anti-TB drugs.

Audiometric Profile of Patients on Treatment for Drug-Resistant Pulmonary Tuberculosis in Owerri, South-East Nigeria.

Background: Tuberculosis is an existential medical challenge in certain parts of the world necessitating global efforts. Perhaps more challenging is the treatment of drug-resistant forms of the disease as this requires use of second line drugs, predominantly potentially ototoxic aminoglycosides. The hearing impairment so caused, besides constituting social disability, can impair compliance and have far-reaching consequences. This study aimed at assessing the hearing patterns of patients on treatment for drug-resistant pulmonary tuberculosis to determine if, and to what extent their treatment affected their hearing status. Patients and method: The study was an 18-month prospective analysis of consecutive newly diagnosed drug-resistant pulmonary tuberculosis patients in a tertiary hospital in Owerri, Nigeria. Baseline audiometry was conducted on the patients with subsequent monthly audiometry for 3 months during treatment. A control group drawn from normal population and matched for age and sex with the study group was recruited and audiometry performed on the participants in similar pattern. The audiometric patterns of both groups were analyzed and compared using Statistical Package for Social Sciences (SPSS) version 20.0 software for Windows. Statistical significance was set at p&lt; 0.05. Results: Thirty-eight (38) patients treated for drug-resistant pulmonary tuberculosis completed the study alongside thirty-eight (38) control subjects with M:F ratio was 1.53:1. The baseline prevalence of hearing impairment of any sort was 73.7% and 68.4% among the test and control groups respectively, whereas after three months it was 89.5% and 68.4% respectively. The cumulative incidence of hearing loss over three months was 15.8% and 0% respectively. This difference was statistically significant. Conclusion: Treatment of drug-resistant tuberculosis with second line drugs can lead to significant hearing impairment within the first three months of treatment.

Use of Short Oral Regimens for Treatment of Drug Resistant Tuberculosis in a Patient with HIV Infection

We present the clinical case of effective treatment of tuberculosis in a patient with disseminated pulmonary and extrapulmonary pre-extensive drug resistant tuberculosis, HIV-infection and other severe opportunistic and concomitant infections. Short all-oral regimen has been used for the treatment. This clinical case demonstrates the clinical efficacy of modern treatment regimens, good compatibility with other drugs and management of adverse events without treatment interruption.

A rapid, accurate, and low-cost method for detecting Mycobacterium tuberculosis and its drug-resistant genes in pulmonary tuberculosis: Applications of MassARRAY DNA mass spectrometry.

Mycobacterium tuberculosis (MTB) identification and drug resistance diagnosis are very important for treatment of drug-resistant tuberculosis (DR-TB). Therefore, high throughput, accurate and low-cost molecular detection techniques are urgently needed. This study aimed to evaluate the clinical application value of MassARRAY in tuberculosis diagnosis and drug resistance screening. The limit of detection (LOD) and clinical application value of MassARRAY were evaluated using reference strains and clinical isolates. MTB in bronchoalveolar lavage fluid (BALF) and sputum samples were detected using MassARRAY, quantitative real-time polymerase chain reaction (qPCR) and MGIT960 liquid culture (culture). Using culture as the standard, the efficacy of MassARRAY and qPCR for the detection of TB was analyzed. Mutation of drug resistance genes in MTB clinical isolates was tested using MassARRAY, high-resolution melting curve (HRM), and Sanger sequencing. Using sequencing as the standard, the efficacy of MassARRAY, and HRM for the detection of each drug resistance site of MTB was analyzed. Simultaneously, the mutation of drug resistance genes by the MassARRAY method was compared with the results of drug susceptibility testing (DST), and the genotype-phenotype relationship was analyzed. The ability of MassARRAY to discriminate mixed infections was detected using mixtures of standard strains (M. tuberculosis H37Rv) and drug-resistant clinical isolates and mixtures of wild-type and mutant plasmids. In MassARRAY, 20 related gene mutations could be detected by two PCR systems. All genes could be accurately detected when the bacterial load was 104 CFU/mL. When the load of wild-type and drug-resistant MTB mixture was 105 CFU/mL (respectively reached 104 CFU/mL), variants and wild-type genes could be detected simultaneously. The sensitivity of MassARRAY (96.9%) for identification was higher than that of qPCR (87.5%) (p < 0.001). The sensitivity and specificity of MassARRAY for all drug resistance gene mutations were 100.0%, with higher accuracy and consistency than HRM (sensitivity = 89.3% and specificity = 96.9%, p = 0.001). Analyzing the relationship between MassARRAY genotype and DST phenotype, the accuracy of katG_315, rpoB_531, rpsL_43, rpsL_88, and rrs_513 sites was 100.0%, and embB_306 and rpoB_526 were inconsistent with the DST results when the base changes were different. MassARRAY can obtain base mutation information and identify heteroresistance infections simultaneously when the mutant proportion was at least 5-25%. It has good application prospects in the diagnosis of DR-TB with high throughput, accurate and low-cost.

Novel Approaches for the Treatment of Drug-Resistant Tuberculosis

Pharmacognosy Research,2023,15,2,235-241.DOI:10.5530/pres.15.2.025Published:February 2023Type:Review ArticleAuthors:Sonam Pushkar, Vibhav Varshney, Pushpendra Pushkar, and Harish Kumar Sagar Author(s) affiliations:Sonam Pushkar1,*, Vibhav Varshney2, Pushpendra Pushkar3, Harish Kumar Sagar4 1Department of Pharmacy, GSVM Medical College, Kanpur, Uttar Pradesh, INDIA. 2Institute of Pharmaceutical Research, GLA University, Mathura, Uttar Pradesh, INDIA. 3Department of Pharmacology, GSVM Medical College, Kanpur, Uttar Pradesh, INDIA. 4ICMR National JALMA Institute for Leprosy and Other Mycobacterial Diseases, Agra, Uttar Pradesh, INDIA. Abstract:Tuberculosis (TB) is a leading infectious disease that caused the deaths of a total of 1.5 million people in 2020 and is one of the top causes of death globally. India is a country with the highest TB burden, and it may affect all age groups. It is caused by the Mycobacterium tuberculosis bacteria, an intracellular pathogen, and its multidrug and extensively drug-resistant strains, which continue to emerge and spread, resulting in the deadliest infectious disease. After a gap of more than 40 years, the FDA approvals over the past decade of three second-line anti-TB drugs, bedaquiline, delamanid, and pretomanid, have been major forward steps in the management of drug-resistant-TB (DR-TB). Many medicinal plants such as Zanthoxylum leprieurii, Lantana camara, and Cryptolepis sanguinolenta have extensive therapeutic potential and represent a prospective option to fight against DR-TB. Some novel compounds are in the early clinical trial phases such as DprE1 inhibitors TBA-7371 and BTZ-043, and many others that are showing promising futures. This review describes DR-TB and its current chemotherapy guidelines including novel and repurposed drugs that are included in the anti-TB regimens, medicinal plants that have therapeutic potential for the development of drug-hit candidates, drugs that are currently in clinical development, host-directed therapy, and new drug delivery systems to better understand the novel therapeutic approaches that are currently being studied for the efficacious and safe management of DR-TB, a worldwide health problem. Keywords:Drug-resistant tuberculosis, immunomodulators., Medicinal plants, Nanotubes, NitroimidazolesView:PDF (189.22 KB)

Variation in missed doses and reasons for discontinuation of anti-tuberculosis drugs during hospital treatment for drug-resistant tuberculosis in South Africa.

Updated World Health Organization (WHO) treatment guidelines prioritize all-oral drug-resistant tuberculosis (DR-TB) regimens. Several poorly tolerated drugs, such as amikacin and para-aminosalicylic acid (PAS), remain treatment options for DR-TB in WHO-recommended longer regimens as Group C drugs. Incomplete treatment with anti-TB drugs increases the risk of treatment failure, relapse, and death. We determined whether missed doses of individual anti-TB drugs, and reasons for their discontinuation, varied in closely monitored hospital settings prior to the 2020 WHO DR-TB treatment guideline updates. We collected retrospective data on adult patients with microbiologically confirmed DR-TB between 2008 and 2015 who were selected for a study of acquired drug resistance in the Western Cape Province of South Africa. Medical records through mid-2017 were reviewed. Patients received directly observed treatment during hospitalization at specialized DR-TB hospitals. Incomplete treatment with individual anti-TB drugs, defined as the failure to take medication as prescribed, regardless of reason, was determined by comparing percent missed doses, stratified by HIV status and DR-TB regimen. We applied a generalized mixed effects model. Among 242 patients, 131 (54%) were male, 97 (40%) were living with HIV, 175 (72%) received second-line treatment prior to first hospitalization, and 191 (79%) died during the study period. At initial hospitalization, 134 (55%) patients had Mycobacterium tuberculosis with resistance to rifampicin and isoniazid (multidrug-resistant TB [MDR-TB]) without resistance to ofloxacin or amikacin, and 102 (42%) had resistance to ofloxacin and/or amikacin. Most patients (129 [53%]) had multiple hospitalizations and DST changes occurred in 146 (60%) by the end of their last hospital discharge. Incomplete treatment was significantly higher for amikacin (18%), capreomycin (18%), PAS (17%) and kanamycin (16%) than other DR-TB drugs (P<0.001), including ethionamide (8%), moxifloxacin (7%), terizidone (7%), ethambutol (7%), and pyrazinamide (6%). Among the most frequently prescribed drugs, second-line injectables had the highest rates of discontinuation for adverse events (range 0.56-1.02 events per year follow-up), while amikacin, PAS and ethionamide had the highest rates of discontinuation for patient refusal (range 0.51-0.68 events per year follow-up). Missed doses did not differ according to HIV status or anti-TB drug combinations. We found that incomplete treatment for second-line injectables and PAS during hospitalization was higher than for other anti-TB drugs. To maximize treatment success, interventions to improve person-centered care and mitigate adverse events may be necessary in cases when PAS or amikacin (2020 WHO recommended Group C drugs) are needed.

Whole-genome sequencing-based analyses of drug-resistant Mycobacterium tuberculosis from Taiwan

Drug-resistant tuberculosis (DR-TB) posed challenges to global TB control. Whole-genome sequencing (WGS) is recommended for predicting drug resistance to guide DR-TB treatment and management. Nevertheless, data are lacking in Taiwan. Phenotypic drug susceptibility testing (DST) of 12 anti-TB drugs was performed for 200 Mycobacterium tuberculosis isolates. WGS was performed using the Illumina platform. Drug resistance profiles and lineages were predicted in silico using the Total Genotyping Solution for TB (TGS-TB). Using the phenotypic DST results as a reference, WGS-based prediction demonstrated high concordance rates of isoniazid (95.0%), rifampicin (RIF) (98.0%), pyrazinamide (98.5%) and fluoroquinolones (FQs) (99.5%) and 96.0% to 99.5% for second-line injectable drugs (SLIDs); whereas, lower concordance rates of ethambutol (87.5%), streptomycin (88.0%) and ethionamide (84.0%). Furthermore, minimum inhibitory concentrations confirmed that RIF rpoB S450L, FQs gyrA D94G and SLIDs rrs a1401g conferred high resistance levels. Besides, we identified lineage-associated mutations in lineage 1 (rpoB H445Y and fabG1 c-15t) and predominant lineage 2 (rpoB S450L and rpsL K43R). The WGS-based prediction of drug resistance is highly concordant with phenotypic DST results and can provide comprehensive genetic information to guide DR-TB precision therapies in Taiwan.

Relative bioavailability of delamanid 50 mg tablets dispersed in water in healthy adult volunteers.

Delamanid is a novel drug for the treatment of drug-resistant tuberculosis, manufactured as 50-mg solid and 25-mg dispersible tablets. We evaluated the effects of dispersing the 50-mg tablet, focusing on the relative bioavailability. Delamanid, 50-mg tablets administered dispersed vs swallowed whole, was investigated in a phase I, four-period, crossover study. Two of three dose strengths of delamanid (25, 50 or 100 mg) were given to healthy adult participants, in both whole and dispersed forms, with a 7-day washout period. Blood samples were collected over 168 h after each dose. Delamanid and its metabolite DM-6705 were analysed with a validated liquid chromatography tandem mass spectrometry assay. The pharmacokinetics of both analytes were analysed using nonlinear mixed-effect modelling. Palatability and acceptability were determined using a standardized questionnaire. Twenty-four participants completed the study. The bioavailability of dispersed tablets was estimated to be 107% of whole tablets, with a 90% confidence interval of 99.7-114%, fulfilling bioequivalence criteria. The two formulations were not significantly different regarding either bioavailability or its variability. Bioavailability increased at lower doses, by 34% (26-42%) at 50 mg and by 74% (64-86%) at 25 mg, relative to 100 mg. The majority of participants (93%) found the dispersed formulation acceptable in palatability across all delamanid doses. Dispersed 50-mg delamanid tablets have similar bioavailability to tablets swallowed whole in adult volunteers. This can be an option for children and other patients who cannot swallow whole tablets, improving access to treatment.

Structure-Activity Relationship of Novel Pyrimidine Derivatives with Potent Inhibitory Activities against Mycobacterium tuberculosis.

Discovery of novel antitubercular drugs is an effective strategy against drug-resistant tuberculosis (TB). Our previous study has identified LPX-16j as a novel antitubercular compound. Herein, we perform a comprehensive structure-activity relationship (SAR) based on LPX-16j, indicating that the central pyrimidine ring moiety was crucial for the antitubercular activities of its derivatives, and replacing the naphthyl group with hydrophobic substitutes was well tolerated. The representative derivative 5a exhibited potent activity against H37Ra, H37Rv, and clinical drug-resistant TB with minimum inhibitory concentration (MIC) values of 0.5-1.0 μg/mL. Meanwhile, 5a showed an acceptable safety in vivo and displayed a favorable oral bioavailability with a value of 40.7%. The differential scanning fluorescence, isothermal titration calorimetry, and molecular docking assays indicated that PknB could be one of the targets of compound 5a. Overall, this study identified 5a as a novel promising lead compound with the potential to develop candidates for the treatment of drug-resistant TB.

Clofazimine for the treatment of tuberculosis.

Shorter (6-9months), fully oral regimens containing new and repurposed drugs are now the first-choice option for the treatment of drug-resistant tuberculosis (DR-TB). Clofazimine, long used in the treatment of leprosy, is one such repurposed drug that has become a cornerstone of DR-TB treatment and ongoing trials are exploring novel, shorter clofazimine-containing regimens for drug-resistant as well as drug-susceptible tuberculosis. Clofazimine's repurposing was informed by evidence of potent activity against DR-TB strains in vitro and in mice and a treatment-shortening effect in DR-TB patients as part of a multidrug regimen. Clofazimine entered clinical use in the 1950s without the rigorous safety and pharmacokinetic evaluation which is part of modern drug development and current dosing is not evidence-based. Recent studies have begun to characterize clofazimine's exposure-response relationship for safety and efficacy in populations with TB. Despite being better tolerated than some other second-line TB drugs, the extent and impact of adverse effects including skin discolouration and cardiotoxicity are not well understood and together with emergent resistance, may undermine clofazimine use in DR-TB programmes. Furthermore, clofazimine's precise mechanism of action is not well established, as is the genetic basis of clofazimine resistance. In this narrative review, we present an overview of the evidence base underpinning the use and limitations of clofazimine as an antituberculosis drug and discuss advances in the understanding of clofazimine pharmacokinetics, toxicity, and resistance. The unusual pharmacokinetic properties of clofazimine and how these relate to its putative mechanism of action, antituberculosis activity, dosing considerations and adverse effects are highlighted. Finally, we discuss the development of novel riminophenazine analogues as antituberculosis drugs.

Identification of seven types of pili in Mycobacterium tuberculosis: Using atomic force microscopy.

Pili are polymeric, hydrophobic, proteinaceous structures generally composed of a major repeating subunit called pilin and, in some cases, a minor tip-associated adhesin subunit. Pili are involved in many virulence-associated functions, such as biofilm formation, adherence, and colonization of mucosal surfaces. Mycobacterium tuberculosis (MTB) strains were isolated from clinically and laboratory-confirmed cases of tuberculosis (TB). The TB isolates were subjected to the Xpert MTB/rifampicin test and then, further susceptibility testing was performed on them against first- and second-line drugs using proportional methods. Thereafter, the selected isolates were subculture in Dubos Tween-albumin liquid culture medium, and at their exponential growth phase (OD600 = 0.05 (5 × 106 colony-forming unit/mL), cells were observed under atomic force microscopy (AFM). For each isolate, 15-20 steel sample packs were prepared and observed under AFM. Here, the data presented are the result of average observation. Under AFM, seven different types of pili were detected, out of which four types, i.e., Type III, Type IV secretion pili, and Type IV-like pili, curli-like pili (MTP) were similar to reported pili in Gram-negative and Gram-positive bacteria. Whereas the other three forms, i.e., Type V (relief funnel pili), Type VI (adhesion tapering), and Type VII (adhesion flap pili), were newly identified and named according to their appearance. Both Types of IV pili were detected in all clinical isolates irrespective of their susceptibility patterns, although significant differences were observed from the side of their protruding. Type Curli pili is similar in appearance in all clinical isolates. Types VI and VII were detected only in extensively drug-resistant and totally drug-resistant-TB isolates (100%). The Type III pili (secretion needle pili) was present in both susceptible- and drug-resistant bacilli, although in drug-resistant strains, we found a considerable difference in their length (50 μ ±10 nm in length) and sometimes, they also had tapering at end. The Type V pili was seen in susceptible isolates but it was at the resting stage (100%; lying aside of cell wall) whereas in drug-resistant isolates, they were getting apart from the cell wall of bacilli with a clear tapering or funnel shape structure. The results of this study highlight the importance of new types of pili expressions in respect of susceptibility patterns in TB. The identified new types of pili would be promising approaches for the treatment and prevention of drug-resistant TB, which needs further investigation.

What Makes People With Chronic Illnesses Discontinue Treatment? A Practice Theory Informed Analysis of Adherence to Treatment among Patients With Drug-Resistant Tuberculosis in Pakistan.

Non-adherence to treatment is a frequently observed phenomenon amongst those on long-term treatment for chronic illnesses. This qualitative study draws upon the tenets of 'practice theory' to reveal what shapes patients' ability to adhere to the demanding treatment for drug-resistant tuberculosis (DR-TB) at three treatment sites in Khyber-Pakhtunkhwa (KP) province of Pakistan. This qualitative study involved observation of service provision over a period of nine months of stay at, and embedment within the three treatment sites and in-depth interviews with 13 service providers and 22 patients who became non-adherent to their treatment. Consistent with the extensive research based on the barriers and facilitator approach, both patients, and providers in our study also talked of patients' doubts about diagnosis and treatment efficacy, side-effects of drugs, economic constraints, unreliable disbursements of monetary incentive, attitude of providers and co-morbidities as reasons for non-adherence to treatment. Applying a practice theory perspective yielded more contextualised insights; inadequate help with patients' physical complaints, unempathetic responses to their queries, and failure to provide essential information, created conditions which hindered the establishment and maintenance of the 'practice' of adhering to treatment. These supply-side gaps created confusion, bred resentment, and exacerbated pre-existing distrust of public health services among patients, and ultimately drove them to disengage with the TB services and stop their treatment. We argue that the lack of supply-side 'responsiveness' to patient needs beyond the provision of a few material inputs is what is lacking in the existing DR-TB program in Pakistan. We conclude that unless Pakistan's TB program explicitly engages with these supply side, system level gaps, patients will continue to struggle to adhere to their treatments and the TB program will continue to lose patients. Conceptually, we make a case for reimagining the act of adherence (or not) to long-term treatment as a 'Practice.'

Novel six-month all oral treatment of pre-extensively drug-resistant tuberculosis in Canada: New treatment options present new implementation challenges.

Drug-resistant tuberculosis (TB) is a major global health challenge in part because there are fewer effective treatments and these treatments have been prolonged and more toxic. The evidence base for more effective, shorter, standardized treatments is evolving rapidly. Herein, we report the first case of pre-extensively drug-resistant pulmonary TB treated with a novel six-month all oral bedaquiline, pretomanid and linezolid (BPaL) regimen in Canada. Recent clinical trial data supporting BPaL therapy is presented in the context of current and evolving clinical guidelines. In this article, we highlight significant implementation challenges and make recommendations for what needs to be addressed to ensure safe programmatic use of BPaL in Canada. Key recommendations include the development of infrastructure for timely access to novel TB drug susceptibility testing, streamlining access to novel TB drugs, and cautious use of such drugs in collaboration with care teams with expertise in drug-resistant TB management.

Highly Sensitive Detection of Complicated Mutations of Drug Resistance in Mycobacterium tuberculosis Using a Simple, Accurate, Rapid, and Low-Cost Tailored-Design Competitive Wild-Type Blocking Assay.

Establishing simple, rapid, and highly sensitive molecular assays is crucial for timely diagnosis and effective treatment of drug-resistant tuberculosis. However, current genotypic drug susceptibility testing (DST) still encounters enormous challenges including lower sensitivity than phenotypic DST and insufficient accuracy. Herein, a simple, low-cost, multiplex real-time polymerase chain reaction-based assay is established to achieve highly sensitive detection of low-abundant mutants through competitive wild-type blocking (COWTB). Analytical performance of the COWTB assay can achieve 1% or even 0.1% mutants under background of 10000 wild-type genomes/test. Furthermore, clinical practice feasibility is evaluated to identify resistance to rifampicin (RIF), isoniazid (INH), and streptomycin (SM) on 92 actual clinical samples, its sensitivity is 93.8% for RIF and 100% for INH and SM, and specificity is 100% each for RIF, INH, and SM when using DNA sequencing as the reference standard. In comparison, the sensitivity of reverse dot blotting assay commonly used in clinics is 93.8%, 90.0%, and 84.6%, and the specificity is 96.1%, 98.6%, and 100% for RIF, INH, and SM, respectively. Importantly, the COWTB assay can also be applicable for other drug-resistant mutations and pave a promising detection strategy to fill the gap between phenotypic and genotypic DST for detecting low-abundant drug-resistant M. tuberculosis.

Specific Manifestations of Neurotoxicity of Some Drug Combinations for Treatment of Drug Resistant Tuberculosis from the Perspective of Experimental Studies

The objective: to evaluate comparative neurotoxicity of combinations of anti-tuberculosis and antimicrobial drugs with different and similar toxic potentials assessing behavioral changes in rats.Subjects and Methods: non-linear female rats divided in 3 groups were used in this study. For 14 days, the rats received a daily combinations of drugs: Group 1 – Mxf + Lzd + Cs + Pto, Group 2 – Mxf + Bdq + Cs + Z , and Group 3 – Bdq + Lzd + Cfz + Z. Neurotoxicity was assessed by changes in behavioral responses using Open Field Test. The number of crossed squares and racks was recorded which characterized horizontal and vertical activity, also peeping into burrows (exploratory activity), the number of groomings (washing and scratching) and physiological functions were registered.Results. In rats of Group 1 versus baseline parameters, we observed a significant limitation of horizontal motor activity and a sharp decrease (by 5 times) in exploratory activity, a 2.8-fold decrease in the number of groomings which indicated emotional suppression. In rats of Groups 2 and 3, the decrease in motor and exploratory activity was insignificant but there was a more pronounced emotional depression. The use of the Mxf + Lzd + Cs + Pto combination in which all drugs possessed a neurotoxic potential, led to diverse and profound changes in behavioral responses which indicated a pronounced neurotoxic effect.