Drug-resistant Mycobacterium Tuberculosis Research Articles

Catalase activity deficiency sensitizes multidrug-resistant Mycobacterium tuberculosis to the ATP synthase inhibitor bedaquiline.

Multidrug-resistant tuberculosis (MDR-TB), defined as resistance to the first-line drugs isoniazid and rifampin, is a growing source of global mortality and threatens global control of tuberculosis disease. The diarylquinoline bedaquiline has recently emerged as a highly efficacious drug against MDR-TB and kills Mycobacterium tuberculosis by inhibiting mycobacterialATP synthase. However, themechanisms underlying bedaquiline's efficacy against MDR-TB remain unknown. Here we investigate bedaquiline hyper-susceptibility in drug-resistant Mycobacterium tuberculosis using systems biology approaches. We discovered that MDR clinical isolates are commonly sensitized to bedaquiline. This hypersensitization is caused by several physiological changes induced by deficient catalase activity. These include enhanced accumulation of reactive oxygen species, increased susceptibility to DNA damage, induction of sensitizing transcriptional programs, and metabolic repression of several biosynthetic pathways. In this work we demonstrate how resistance-associated changes in bacterial physiology can mechanisticallyinduce collateral antimicrobial drug sensitivity and reveal druggable vulnerabilities in antimicrobial resistant pathogens.

In vitro monitoring of drug resistance emergence during stepwise induction of bedaquiline and clofazimine, alone and in combination: a phenotypic and genotypic analysis.

The co-resistance between bedaquiline and clofazimine raises significant concerns, as they are commonly co-administered as core drugs in drug-resistant TB regimens. The present study aimed to monitor drug resistance-associated gene mutations and the phenotypic change in Mycobacterium tuberculosis (Mtb) under a stepwise drug resistance induction in vitro using bedaquiline, clofazimine or combined drugs. Drug-resistant Mtb strains were gradually induced in vitro on a drug-containing solid medium with a 2-fold increasing concentration of bedaquiline, clofazimine and their combination. The MIC of the induced drug-resistant Mtb strains was determined. The drug resistance-associated genes, including Rv0678, Rv1979c, atpE and pepQ, were sequenced and analysed. Unlike exposure to bedaquiline alone or the combination of these two drugs, clofazimine alone resulted in drug resistance gene mutations occurring later, specifically in the fourth round of induction as opposed to the second round of induction. Besides, nucleotide deletion or insertion in Rv0678 was the main mutation type for induction under the two-drug combination, while single-nucleotide polymorphisms (SNPs) in Rv0678 were the major mutation types when induced by bedaquiline or clofazimine alone. Rv0678 mutation happened at a relatively lower bedaquiline concentration exposure alone, while atpE mutation occurred at a higher bedaquiline concentration. Regardless of the drug exposure manner, a strong correlation between bedaquiline MICs and clofazimine MICs was observed in all drug resistance strains. Combined exposure to bedaquiline and clofazimine developed Rv0678 mutation as early as exposure to bedaquiline alone. However, rather than SNPs, deletion and insertion were the dominant mutation types in dual-drug exposure strain.

Discovery of potent dihydro-oxazinoquinolinone inhibitors of GuaB for the treatment of tuberculosis

Tuberculosis is the leading cause of death from an infectious disease, and is caused by Mycobacterium tuberculosis (M.tb). More than 1 billion people worldwide are thought to harbor an M.tb infection. The multidrug therapy that represents the current standard of care requires a minimum of four months of dosing and drug resistant Mycobacterium tuberculosis treatment regimens are significantly longer. Inosine-5′-monophosphate dehydrogenase (GuaB) is the enzyme that performs the rate-limiting step in de novo guanine nucleotide biosynthesis that is critical for growth and viability of bacteria including M.tb. The development of a novel antibiotic that inhibits GuaB could combine with existing therapies in novel ways and thereby contribute to effective therapeutic regimens for the treatment of tuberculosis. Here we describe the discovery of structurally distinct small molecule GuaB inhibitors that are potent against M.tb H37Ra and H37Rv strains and have desirable safety and AMDE profiles.

Drug repurposing: An antidiabetic drug Ipragliflozin as Mycobacterium tuberculosis sirtuin-like protein inhibitor that synergizes with anti-tuberculosis drug isoniazid

The surge of drug-resistant Mycobacterium tuberculosis (DR-TB) impedes the World Health Organization's efforts in ending TB and calls for new therapeutic formulations. M. tuberculosis sirtuin-like protein Rv1151c is a bifunctional enzyme with both deacetylation and desuccinylation activities, which plays an important role in M. tuberculosis drug resistance and stress responses. Thus, it appears to be a promising target for the development of new TB therapeutics. In this study, we screened 31,057 ligand compounds from seven compound libraries in silico to identify inhibitors of Rv1151c. Ipragliflozin can bind to Rv1151c and interact stably. Ipragliflozin can change the acylation level of M. tuberculosis by inhibiting Rv1151c and effectively inhibit the growth of M. tuberculosis H37Rv and M. smegmatis. It can potentiate the first-front anti-TB drug isoniazid. As an antidiabetic drug, Ipragliflozin can be potentially included in the regimen to treat diabetes-tuberculosis comorbidity.

Toxoplasma gondii macrophage migration inhibitory factor shows anti-Mycobacterium tuberculosis potential via AZIN1/STAT1 interaction.

Mycobacterium tuberculosis (MTB) is a pathogenic bacterium, belonging to the family Mycobacteriaceae, that causes tuberculosis (TB). Toxoplasma gondii macrophage migration inhibitory factor (TgMIF), a protein homolog of macrophage migration inhibitory factor, has been explored for its potential to modulate immune responses during MTB infections. We observed that TgMIF that interacts with CD74, antizyme inhibitor 1 (AZIN1), and signal transducer and activator of transcription 1 (STAT1) modulates endocytosis, restoration of mitochondrial function, and macrophage polarization, respectively. These interactions promote therapeutic efficacy in mice infected with MTB, thereby presenting a potential route to host-directed therapy development. Furthermore, TgMIF, in combination with first-line TB drugs, significantly inhibited drug-resistant MTB strains, including multidrug-resistant TB. These results demonstrate that TgMIF is potentially a multifaceted therapeutic agent against TB, acting through immune modulation, enhancement of mitochondrial function, and dependent on STAT1 and AZIN1 pathways.

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.

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.

Mechanism research of Tollip negative feedback regulation in TLR4 signaling pathways based on spinal tuberculosis: Detection of Tollip and NF-κB expression levels

The emergence of drug-resistant mycobacterium tuberculosis (MTB, or TB) strains has led to an increasing incidence of TB. Spinal tuberculosis is the most common extrapulmonary tuberculosis. In the present study, tollip, a negative feedback regulatory factor in TLR4 signaling pathway was chosen based on previous studies on osteoarticular tuberculosis. U937 cells were transfected with recombinant lentivirus containing shRNA (RNA interference, RNAi) or overexpression vector containing Tollip gene and tested in vitro. The expression levels of Tollip and TLR4 were detected by Real-time PCR and immunofluorescence techniques, and the cell morphology and infection effect were observed by DAPI staining. The results suggested that Tollip gene could negatively inhibit the expression of related factors in TLR4 signaling pathway, and thus is a potential biomarker for early diagnosis.

Discovery of benzo[c]phenanthridine derivatives with potent activity against multidrug-resistant Mycobacterium tuberculosis.

Mycobacterium tuberculosis (Mtb), the pathogen responsible for tuberculosis (TB), is the leading cause of bacterial disease-related death worldwide. Current antibiotic regimens for the treatment of TB remain dated and suffer from long treatment times as well as the development of drug resistance. As such, the search for novel chemical modalities that have selective or potent anti-Mtb properties remains an urgent priority, particularly against multidrug-resistant (MDR) Mtb strains. Herein, we design and synthesize 35 novel benzo[c]phenanthridine derivatives (BPDs). The two most potent compounds, BPD-6 and BPD-9, accumulated within the bacterial cell and exhibited strong inhibitory activity (MIC90 ~2 to 10 µM) against multiple Mycobacterium strains while remaining inactive against a range of other Gram-negative and Gram-positive bacteria. BPD-6 and BPD-9 were also effective in reducing Mtb survival within infected macrophages, and BPD-9 reduced the burden of Mycobacterium bovis BCG in the lungs of infected mice. The two BPD compounds displayed comparable efficacy to rifampicin (RIF) against non-replicating Mtb (NR-Mtb). Importantly, BPD-6 and BPD-9 inhibited the growth of multiple MDR Mtb clinical isolates. Generation of BPD-9-resistant mutants identified the involvement of the Mmr efflux pump as an indirect resistance mechanism. The unique specificity of BPDs to Mycobacterium spp. and their efficacy against MDR Mtb isolates suggest a potential novel mechanism of action. The discovery of BPDs provides novel chemical scaffolds for anti-TB drug discovery.IMPORTANCEThe emergence of drug-resistant tuberculosis (TB) is a serious global health threat. There remains an urgent need to discover new antibiotics with unique mechanisms of action that are effective against drug-resistant Mycobacterium tuberculosis (Mtb). This study shows that novel semi-synthetic compounds can be derived from natural compounds to produce potent activity against Mtb. Importantly, the identified compounds have narrow spectrum activity against Mycobacterium species, including clinical multidrug-resistant (MDR) strains, are effective in infected macrophages and against non-replicating Mtb (NR-Mtb), and show anti-mycobacterial activity in mice. These new compounds provide promising chemical scaffolds to develop potent anti-Mtb drugs of the future.

3,5-disubstituted pyridines with potent activity against drug-resistant Mycobacterium tuberculosis clinical isolates.

Aim: We designed and synthesized a series of compounds with a 3,5-disubstituted pyridine moiety and evaluated them against Mycobacterium tuberculosis (Mtb) and drug-resistant Mtb clinical isolates.Methodology: A library of 3,5-disubstituted pyridine was synthesized. The compounds were screened for activity against M. tuberculosis H37Rv. The optimal substitutions needed for the activity were identified through structure-activity relationship (SAR) studies.Results: From the screening studies, compounds 24 and 26 were identified as potent members of this series with Minimum Inhibitory Concentration (MIC) of 1.56μg/ml against M. tuberculosis H37Rv. These compounds did not show any inhibition against a panel of ESKAPE pathogens at >50μg/ml indicating their selective killing of M. tuberculosis H37Rv. Importantly, compound 24 showed a selectivity index of 54.64 against CHO-K1 and 78.26 against VERO cell lines, while compound 26 showed a selectivity index of 108.5 against CHO-K1 and 63.2 against VERO cell lines, respectively. Compound 24 formed a stable complex with the target protein DprE1 with predicted binding energy -8.73kcal/mol and inhibited multidrug-resistant clinical isolate of M. tuberculosis at 6.25μg/ml.Conclusion: This study identified the 3,5-disubstituted pyridine derivative 24 with potent antituberculosis activity and can be taken forward to generate new preclinical candidate.

Synthesis and InhA Inhibition of Imidazo[1,2-a]pyridine Derivatives as Anti-Tuberculosis Agents

Abstract: Imidazopyridine holds significance as a crucial fused bicyclic heterocycle within the realm of medicinal chemistry, being acknowledged as a "privileged scaffold" owing to its extensive utility. Numerous methodologies for the synthesis of imidazo[1,2-a]pyridines have been documented, with a considerable focus on strategies aimed at functionalizing these compounds. This study aimed to explore the potential of novel imidazo[1,2- a] pyridine derivatives as agents against drug-resistant Mycobacterium tuberculosis, which poses significant challenges in tuberculosis (TB) treatment. The research involved the synthesis of substituted imidazo[1,2- a]pyridine derivatives using site identification and molecular docking techniques. Characterization of the synthesized compounds was carried out using FT-IR, LC-MS, 1H NMR, and 13C NMR analysis. Compounds 6a and 6k showed good anti-TB activity against the H37Rv strain of Mycobacterium tuberculosis, with MIC values of 0.6 μM and 0.9 μM, respectively, which were comparable with the standard drug isoniazid. These findings suggest that imidazo[1,2-a]pyridine derivatives, especially compounds 6a and 6k, have potential as agents against drug-resistant TB, providing valuable insights for ongoing efforts in developing effective TB treatments.

Mutations in Rv0678, Rv2535c, and Rv1979c Confer Resistance to Bedaquiline in Clinical Isolates of Mycobacterium Tuberculosis.

Reduced bedaquiline (BDQ) sensitivity to antimycobacterial drugs has been linked to mutations in the Rv0678, pepQ, and Rv1979c genes of Mycobacterium tuberculosis (MTB). Resistance-causing mutations in MTB strains under treatment may have an impact on novel BDQ-based medication regimens intended to reduce treatment time. Due to this, we investigated the genetic basis of BDQ resistance in Turkish TB patients with MTB clinical isolates. Furthermore, mutations in the genes linked to efflux pumps were examined as a backup resistance mechanism. We scrutinized 100 MTB clinical isolates from TB patients using convenience sampling. Eighty MDR and twenty pan-drug susceptible MTB strains were among these isolates. Sequencing was performed on all strains, and genomic analyses were performed to find mutations in BDQ resistance-associated genes, including Rv0678 and pepQ(Rv2535c), which correspond to a putative Xaa-Pro aminopeptidase, and Rv1979c. Of the 74 isolates with PepQ (Rv2535c) mutations, four isolates (2.96%) exhibited MGIT-BDQ susceptibility. Twenty-one (19.11%) of the ninety-one isolates carrying mutations, including Rv1979c, were MGIT-BDQ-sensitive. Nonetheless, out of the 39 isolates with Rv0678 mutations, four (2.96%) were sensitive to MGIT-BDQ. It was found that resistance-associated variants (RAVs) in Rv0678, pepQ, and Rv1979c are often linked to BDQ resistance. In order to include variations in efflux pump genes in genome-based diagnostics for drug-resistant MTB, further evidence about their involvement in resistance is needed.

Identification of Chemical Scaffolds That Inhibit the Mycobacterium tuberculosis Respiratory Complex Succinate Dehydrogenase.

Drug-resistant Mycobacterium tuberculosis is a significant cause of infectious disease morbidity and mortality for which new antimicrobials are urgently needed. Inhibitors of mycobacterial respiratory energy metabolism have emerged as promising next-generation antimicrobials, but a number of targets remain unexplored. Succinate dehydrogenase (SDH), a focal point in mycobacterial central carbon metabolism and respiratory energy production, is required for growth and survival in M. tuberculosis under a number of conditions, highlighting the potential of inhibitors targeting mycobacterial SDH enzymes. To advance SDH as a novel drug target in M. tuberculosis, we utilized a combination of biochemical screening and in-silico deep learning technologies to identify multiple chemical scaffolds capable of inhibiting mycobacterial SDH activity. Antimicrobial susceptibility assays show that lead inhibitors are bacteriostatic agents with activity against wild-type and drug-resistant strains of M. tuberculosis. Mode of action studies on lead compounds demonstrate that the specific inhibition of SDH activity dysregulates mycobacterial metabolism and respiration and results in the secretion of intracellular succinate. Interaction assays demonstrate that the chemical inhibition of SDH activity potentiates the activity of other bioenergetic inhibitors and prevents the emergence of resistance to a variety of drugs. Overall, this study shows that SDH inhibitors are promising next-generation antimicrobials against M. tuberculosis.

Compounds Derived from 5-Fluoropyridine and Benzo[b]thiophene: Killing Mycobacterium tuberculosis and Reducing its Virulence.

The rise of drug-resistant Mycobacterium tuberculosis (Mtb) has extended the duration of tuberculosis (TB) treatment and reduced the likelihood of cure. One strategy to combat this issue is the development of inhibitors targeting the virulence factors of bacterial pathogens. Mtb' catalase (KatG) is crucial for its detoxification mechanisms and also serves as a significant virulence factor for the bacterium. In this study, twelve derivatives synthesized from 5-fluoropyridine and benzo[b]thiophene demonstrated antimycobacterial efficacy with minimum inhibitory concentrations (MICs) varying between 0.5 and 32 μg/mL. Compound 2, 1-(benzo[b]thiophen-2-ylmethylene) thiosemicarbazide, emerged as the most potent candidate. It effectively inhibited Mtb KatG, enhanced the production of reactive oxygen species (ROS) in Mtb, and achieved Mtb killing within 96 hours at a concentration of 2 μg/mL (4×MIC). Molecular docking simulations revealed that compound 2 binds tightly to the active site of Mtb-KatG with a docking score of 114, indicating that it may serve as a potent inhibitor of Mtb-KatG. The rabbit skin tuberculosis model was employed to assess the virulence of Mtb. Animal study results indicated that the granulomas induced by Mtb after treatment with compound 2 were reduced in size, exhibited a lower bacterial load, and the bacteria were no longer aggregated, in contrast to those caused by untreated Mtb. Hence, compound 2 can be regarded as a molecule capable of neutralizing the virulence factors of Mtb. This research offers insights into the design of anti-Mtb molecules with novel mechanisms of action.

Design, synthesis and docking studies of new molecular hybrids bearing benzimidazole and thiazolidine-2,4-dione as potential antitubercular agents

Finding novel therapeutic medications to combat tuberculosis (TB) is crucial, as evidenced by the disease's growth as a worldwide health concern in recent decades and the rise of drug-resistant forms of Mycobacterium tuberculosis (Mtb). In this article, we describe the synthesis and design of a novel class of thiazolidine-2,4-dione derivatives (5a-i) based on 1H-benzo [d]imidazoles as antitubercular drugs. Spectroscopic techniques and elemental analysis were used to characterize each of the newly synthesized molecules. The antitubercular activity of all the newly synthesized title compounds was assessed against drug-sensitive Mtb H37Rv, multidrug-resistant (MDR-TB), and extensively drug-resistant (XDR-TB) tuberculosis. Compounds 5e and 5 h had the most antitubercular activity among all the newly synthesized hybrids against drug-sensitive, MDR-TB, and XDR-TB strains, with MIC values ranging from 0.21 to 47.84 μM. When it comes to drug-sensitive, drug-resistant, and XDR Mtb strains, compound 5 h with a trifluoromethyl group is 1.71, 10.86, and 3.50 times more potent, whereas compound 5e with a nitro group is 1.12, 8.50, and 2.61 times more active. Remarkably, the compounds' in vitro cytotoxicity test demonstrated good selectivity indices, highlighting their safety on the normal lung fibroblast (WI-38) cell line experiment. To further understand the interactions between potent hybrids and the target enzyme, molecular docking investigations were conducted against the decaprenyl-phosphoryl-ribose 2′-epimerase (DprE1) enzyme. The target protein exhibited preferentially positive interactions with the potent compounds 5e, 5f, 5 h, and 5i. Relationships between structure-activity as well as drug-likeness were used to connect the freshly synthesized compounds' physical and biological properties. When considered collectively, these results suggest that compounds 5e and 5 h might be promising candidates for the development of drug-sensitive and drug-resistant TB therapies in the future.

Clinical application of whole-genome sequencing in the management of extensively drug-resistant tuberculosis: a case report

BackgroundWhole-genome sequencing (WGS)-based prediction of drug resistance in Mycobacterium tuberculosis has the potential to guide clinical decisions in the design of optimal treatment regimens.MethodsWe utilized WGS to investigate drug resistance mutations in a 32-year-old Tanzanian male admitted to Kibong’oto Infectious Diseases Hospital with a history of interrupted multidrug-resistant tuberculosis treatment for more than three years. Before admission, he received various all-oral bedaquiline-based multidrug-resistant tuberculosis treatment regimens with unfavourable outcomes.ResultsDrug susceptibility testing of serial M. tuberculosis isolates using Mycobacterium Growth Incubator Tubes culture and WGS revealed resistance to first-line anti-TB drugs, bedaquiline, and fluoroquinolones but susceptibility to linezolid, clofazimine, and delamanid. WGS of serial cultured isolates revealed that the Beijing (Lineage 2.2.2) strain was resistant to bedaquiline, with mutations in the mmpR5 gene (Rv0678. This study also revealed the emergence of two distinct subpopulations of bedaquiline-resistant tuberculosis strains with Asp47f and Glu49fs frameshift mutations in the mmpR5 gene, which might be the underlying cause of prolonged resistance. An individualized regimen comprising bedaquiline, delamanid, pyrazinamide, ethionamide, and para-aminosalicylic acid was designed. The patient was discharged home at month 8 and is currently in the ninth month of treatment. He reported no cough, chest pain, fever, or chest tightness but still experienced numbness in his lower limbs.ConclusionWe propose the incorporation of WGS in the diagnostic framework for the optimal management of patients with drug-resistant and extensively drug-resistant tuberculosis.

Identification of antimycobacterial 8-hydroxyquinoline derivatives as in vitro enzymatic inhibitors of Mycobacterium tuberculosis enoyl-acyl carrier protein reductase

The increasing prevalence of drug-resistant Mycobacterium tuberculosis strains stimulates the discovery of new drug candidates. Among them are 8-hydroxyquinoline (8HQ) derivatives that exhibited antimicrobial properties. Unfortunately, there is a lack of data assessing possible targets for this class mainly against Mycobacterium tuberculosis enoyl-acyl carrier protein reductase (MtInhA), a validated target in this field. Thus, the main purpose of this study was to identify 8HQ derivatives that are active against M. tuberculosis and MtInhA. Initially, the screening against the microorganism of a small antimicrobial library and its new derivatives that possess some structural similarity with MtInhA inhibitors identified four 7-substituted-8HQ (series 5 – 5a, 5c, 5d and 5i) and four 5-substituted-8HQ active derivatives (series 7 – 7a, 7c, 7d and 7j). In general, the 7-substituted 8-HQs were more potent and, in the enzymatic assay, were able to inhibit MtInhA at low micromolar range. However, the 5-substituted-8-HQs that presented antimycobacterial activity were not able to inhibit MtInhA. These findings indicate the non-promiscuous nature of 8-HQ derivatives and emphasize the significance of selecting appropriate substituents to achieve in vitro enzyme inhibition. Finally, 7-substituted-8HQ series are promising new derivatives for structure-based drug design and further development.

A study on factors influencing delayed sputum conversion in newly diagnosed pulmonary tuberculosis based on bacteriology and genomics

Conversion of sputum from positive to negative is one of the indicators to evaluate the efficacy of anti-tuberculosis treatment (ATT). We investigate the factors associated with delayed sputum conversion after 2 or 5 months of ATT from the perspectives of bacteriology and genomics. A retrospective study of sputum conversion in sputum positive 1782 pulmonary tuberculosis (PTB) was conducted from 2021 to 2022 in Beijing, China. We also designed a case-matched study including 24 pairs of delayed-sputum-conversion patients (DSCPs) and timely-sputum-conversion patients (TSCPs), and collect clinical isolates from DSCPs before and after ATT and initial isolates of TSCPs who successfully achieved sputum conversion to negative after 2 months of ATT. A total of 75 strains were conducted drug sensitivity testing (DST) of 13 anti-TB drugs and whole-genome sequencing (WGS) to analyze the risk factors of delayed conversion and the dynamics changes of drug resistance and genomics of Mycobacterium tuberculosis (MTB) during ATT. We found TSCPs have better treatment outcomes and whose initial isolates show lower levels of drug resistance. Clinical isolates of DSCPs showed dynamically changing of resistance phenotypes and intra-host heterogeneity. Single nucleotide polymorphism (SNP) profiles showed large differences between groups. The study provided insight into the bacteriological and genomic variation of delayed sputum conversion. It would be helpful for early indication of sputum conversion and guidance on ATT.

Applying whole genome sequencing to predict phenotypic drug resistance in Mycobacterium tuberculosis: leveraging 20 years of nationwide data from Denmark.

Infection with Mycobacterium tuberculosis remains one of the biggest causes of death from a single microorganism worldwide, and the continuous emergence of drug resistance aggravates our ability to cure the disease. New improved resistance detection methods are needed to provide adequate treatment, such as whole genome sequencing (WGS), which has been used increasingly to identify resistance-conferring mutations over the last decade. The steadily increasing knowledge of resistance-conferring mutations increases our ability to predict resistance based on genomic data alone. This study evaluates the performance of WGS to predict M. tuberculosis complex resistance. It compares WGS predictions with the phenotypic (culture-based) drug susceptibility results based on 20 years of nationwide Danish data. Analyzing 6,230 WGS-sequenced samples, the sensitivities for isoniazid, rifampicin, ethambutol, and pyrazinamide were 82.5% [78.0%-86.5%, 95% confidence interval (CI)], 97.3% (90.6%-99.7%, 95% CI), 58.0% (43.2%-71.8%, 95% CI), and 60.5% (49.0%-71.2%, 95% CI), respectively, and specificities were 99.8% (99.7%-99.9%, 95% CI), 99.8% (99.7%-99.9%, 95% CI), 99.4% (99.2%-99.6%, 95% CI), and 99.9% (99.7%-99.9%, 95% CI), respectively. A broader range of both sensitivities and specificities was observed for second-line drugs. The results conform with previously reported values and indicate that WGS is reliable for routine resistance detection in resource-rich tuberculosis low-incidence and low-resistance settings such as Denmark.