Therapeutic option for treating methicillin-resistant Staphylococcus aureus (MRSA) infection is urgently required since its resistance to a broad spectrum of currently available antibiotics. Here, we report that isoniazid is able to potentiate the killing efficacy of tigecycline to MRSA. The combination of isoniazid and tigecycline reduces the minimal inhibitory concentration of clinic MRSA strains to tigecycline. The killing activity of tigecycline is further confirmed by killing experiments and murine infection model. We further demonstrate the mechanism that isoniazid increases intracellular accumulation of tigecycline by promoting the influx but limiting the efflux of tigecycline through proton motive force. We also show that isoniazid and tigecycline synergize to increase the abundance of isoniazid-NAD adduct, which in turn damage cell membrane, possibly contributing to the disruption of PMF. Whereas phosphatidylethanolamine and cardiolipin are able to abrogate the synergistic effect of isoniazid plus tigecycline. Thus our study provides a new perspective that antibiotics, e.g. isoniazid, once recognized only to target Mycobacterium tuberculosis, can be repurposed as antibiotic adjuvant to tigecycline, expanding our choice of antibiotic-antibiotic combinations in treating bacterial infectious diseases.

Isoniazid is primarily metabolized by the arylamine N-acetyltransferase 2 (NAT2) enzyme. Single nucleotide polymorphisms (SNPs) in the NAT2 gene could classify an individual into three distinct phenotypes: rapid, intermediate and slow acetylators. NAT2 SNPs and the slow acetylator phenotype have been implicated as risk factors for the development of antitubercular drug-induced liver injury (AT-DILI) in several tuberculosis (TB) populations.

We conducted a prospective observational study to characterize and compare the NAT2 SNPs, genotypes and phenotypes among patients with TB and AT-DILI from the Southern and Western regions of India. The NAT2 pharmacogenomic profile of patients from these regions was compared with the reports from several geographically diverse TB populations and participants of different genetic ancestries extracted from literature reviews and the 'All of Us' Research Program database, respectively.

The TB patients of Southern and Western regions of India and several other geographically closer regions exhibited near similar NAT2 MAF characteristics. However significant heterogeneity in NAT2 SNPs was observed within and between countries among AT-DILI populations and the participants of different genetic ancestry from the 'All of Us' Research Program database. The MAF of the NAT2 SNPs rs1041983, rs1801280, rs1799929, rs1799930 and rs1208 of the TB patients from Southern and Western Indian Sites were in near range to that of the South Asian genetic ancestry of 'All of Us' Research Program database. About one-third of the total TB patients from the Southern and Western regions of India were NAT2 slow acetylators, among whom a relatively higher proportion experienced AT-DILI.

Further studies exploring the risk of NAT2 SNPs in different AT-DILI patients with larger sample sizes and a population-specific approach are required to establish a policy for NAT2 genotyping as a pre-emptive biomarker for AT-DILI monitoring for personalized isoniazid therapy in clinics.

In vitro maturation (IVM) is a very important technology for the modernization of animal husbandry. Previous studies have demonstrated that the mitochondria-targeting antioxidant mitoquinone mesylate (MitoQ) was known for its protective role in a variety of tissues and cells; however, its function in Tibetan sheep oocytes is not fully understood. This study used a Tibetan sheep model to evaluate the effects of oocytes exposed to MitoQ on maturation and subsequent embryonic development. During IVM, cumulus-oocyte-complexes were exposed to 0-400 nM MitoQ to evaluate the viability of cumulus cells expansion and oocyte maturation, and determine the optimal concentration of 100 nM. Here, we discovered that 100 nM MitoQ addition to the medium improved the Tibetan sheep oocyte maturation rate (P < 0.05) and cumulus cells expansion rate (P > 0.05). In addition, immunostaining showed that decreased ROS levels (P < 0.01), increased GSH levels (P < 0.01). MitoQ-treated oocytes showed enhanced mitochondrial activity (P < 0.01) and mitochondrial membrane potential (P < 0.05). MitoQ increased Ca2 + levels (P < 0.01) and attenuated early apoptosis (P < 0.01). No differences were observed for cleavage rate (P > 0.05), and improved number of blastocyst cells and the blastocyst rate (P < 0.05) after in vitro fertilization. Moreover, various genes associated with oocyte oxidative stress (GCLC, SOD1) in mature oocytes were beneficially regulated in the MitoQ-treated oocytes. In conclusion, MitoQ can enhance the oocyte maturation rate, improve subsequent embryonic development in Tibetan sheep.

Tuberculosis is an infectious condition caused by Mycobacterium tuberculosis, primarily targeting the pulmonary system, with the potential to disseminate to various other organs via the haematogenous pathway, ranking among the top ten causes of global mortality. Tuberculosis remains a serious public health problem worldwide. This narrative review aims to emphasise the clinical importance of the inter-relationships between nutrition, pharmacotherapy, and the most common drug-nutrient interactions in the context of tuberculosis and multi-drug-resistant tuberculosis management. Nowadays, pharmacologic approaches utilise polytherapeutic regimens that, although showing increased efficacy, prominently affect the nutritional status of patients and modify multiple metabolic pathways, thus influencing both the effectiveness of therapy and the patient outcomes. There is much evidence that antituberculosis drugs are associated with deficiencies in essential vitamins and various micronutrients, leading to serious adverse consequences. Moreover, poor nutrition exacerbates TB outcomes, and TB further exacerbates nutritional status, a vicious cycle that is particularly prevalent in low-resource environments. Nutritional support is necessary, and clinicians ought to evaluate it on a patient-by-patient basis, as empirical evidence has shown that it can improve immune recovery, decrease tuberculosis-associated morbidity, and increase adherence to therapy. However, drug-food interactions are increasingly prevalent, and patients with tuberculosis require personalised dietary and pharmacological regimens. In this context, antituberculosis treatment requires a holistic approach, based on the collaboration of the prescribing physician, pharmacist, and nutritionist, to assess the patient's needs from a nutritional and pharmacological perspective, with the ultimate goal of decreasing mortality and improving the prognosis of patients through personalised therapies.

Tuberculosis remains a significant public health challenge globally. The emergence of multidrug-resistant Mycobacterium tuberculosis strains presents one of the biggest hurdles in tuberculosis management. Both first- and second-line tuberculosis drugs are associated with common adverse reactions, which can lead to treatment interruptions and decreased adherence. In this article, we review the most commonly used drugs for the treatment of tuberculosis, focusing on the adverse reactions they may cause. We will examine the frequency and timeline of adverse drug reactions involving gastrointestinal, cardiac, neurological, nephrological, and cutaneous systems. Identifying patients at risk of developing those reactions is crucial for healthcare providers to implement monitoring strategies and manage complications effectively. In the review, we present the data about risk factors, management recommendations, and drug discontinuation rates as a result of side effects.

Given that more than 1 million people annually develop isoniazid-resistant tuberculosis (Hr-TB), the issue of Hr-TB may go unnoticed. However, limited studies have focused on the clinical treatment of Hr-TB in China, particularly regarding treatment outcomes and influencing factors. This study aimed to evaluate the treatment outcomes of Hr-TB patients in Shanghai from 2018 to 2021 and analyse the influencing factors, including demographic characteristics, clinical features, and treatment-related factors.

This study retrospectively reviewed the medical records of Hr-TB patients registered in the TB management information system from 2018 to 2021. Differences in demographic characteristics, clinical information, and treatment outcomes were evaluated. Multivariable logistic regression was used to identify risk factors associated with unfavourable outcomes.

A total of 664 patients with Hr-TB were included in the analysis. A total of 84 cases (12.7%) had unfavourable outcomes. Only 318 (47.9%) Hr-TB patients used regimens containing fluoroquinolones. Adverse events occurred in 127 cases (19.1%), of which 12 cases (1.81%) discontinued treatment due to adverse events. There was statistically significant difference in the occurrence of adverse events between the different treatment regimens (P < 0.001). Multivariable logistic regression showed that older age (adjusted odds ratio = 6.13, 95% confidence intervals [CI] = 1.24-30.24, P = 0.026), use of injectable agents (adjusted odds ratio = 3.75, 95% CI = 1.29-10.94, P = 0.016), and treatment duration (95% CI = 21.85-1487.61, P < 0.001) were risk factors for unfavourable treatment outcomes.

Unfavourable outcomes were more frequent among older patients and those receiving injectable agents among Hr-TB patients in Shanghai, a low-endemic region for TB. This emphasizes the need for timely diagnosis and optimized treatment strategies for isoniazid-resistant tuberculosis.

Acetic acid, as a weak organic acid, has a wide range of food, pharmaceutical, and industrial applications. It is also used as a green solvent, catalyst, and reagent in chemical experiments. Properties such as non-toxicity, safety, availability, and low cost have made it the preferred choice for acetylation processes. In this project, the interactions of a series of alkyl/aryl/heteroaryl hydrazides with acetic acid were investigated under reflux heating. A variety of reactions, including C- and N-acetylation, hydrolysis, and rearrangement, occurred in the presence of acetic acid. Most of the products were recrystallized in good to excellent yields under these conditions without the need for further purification. All synthesized compounds were characterized by NMR (1H and 13C), FT-IR, and CHNS analysis. In addition, a novel method was proposed for the preparation of products 2a and 2i-q. This method has the potential to be extended to similar reagents. To investigate the biological activity and drug-like properties, some in silico methods were employed on the synthesized compounds. Screening using the ChEMBL database revealed that out of 17 synthesized compounds, compounds 2b (ChEMBL93746), 2c (ChEMBL22425), and 2d (ChEMBL441343) exhibited significant activity against targets SIRT1, TPMT, and Tyrosinase, with measured values below 200 μM. Molecular docking demonstrated that compound 2o interacted with all three targets. These findings provide valuable insights into its potential as a promising multi-target drug candidate for future investigations.

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of hospital- and community-acquired infections, necessitating the development of novel antibacterials. Here, we designed and synthesized 30 osthole derivatives with pyridinium quaternary ammonium moieties. In vitro bioassay showed that compounds 8u and 8ac exhibited potent antibacterial activity against S. aureus ATCC 29213 and ten clinical MRSA isolates (MIC = 0.5-1 μg/mL), with low hemolytic activity, rapid bactericidal effects, and minimal resistance induction. In MRSA-infected mouse models of skin abscesses and sepsis, 8u and 8ac also displayed excellent antibacterial effects and safety, which were comparable to vancomycin. Mechanistic studies revealed that 8u and 8ac selectively target bacterial membranes via binding to phosphatidylglycerol (PG), increasing intracellular reactive oxygen species (ROS), inducing content leakage, and ultimately causing bacterial death. These findings suggest 8u and 8ac as promising novel lead candidates for anti-MRSA drug development.

Tuberculosis (TB) is a bacterial disease that poses significant challenges in its treatment. It requires prolonged use of high doses of medication, which can lead to various side effects. These side effects often contribute to low patient adherence to treatment, thereby increasing the risk of developing drug-resistant strains. The SQ109 is a second-generation agent developed from ethambutol that has been emerging as a promising TB agent. The functionalization of its skeleton appears as a strategy to improve the physicochemical and biological properties. Hence, we report the synthesis of functionalized SQ109 scaffolds, the in vitro evaluation against Mycobacterium tuberculosis H37Rv strains, molecular docking simulations, and molecular dynamics of the interactions with the target membrane protein.

Drug resistance in tuberculosis seriously affects the eradication of tuberculosis, and isoniazid resistance is the second most commonly observed drug resistance in patients with tuberculosis. Timely and accurate detection of isoniazid resistance is critical to the treatment of tuberculosis.

A duplex one-step recombinase-aided PCR (DO-RAP) assay was developed for the rapid and sensitive detection of the katG Ser315Thr and inhA-15 (C-T) mutations in Mycobacterium tuberculosis, which are the most common isoniazid-resistant mutations. Quantitative recombinant plasmids were used to evaluate the sensitivity of DO-RAP, and 91 Mycobacterium tuberculosis strains with different genotypes, as well as 5 common respiratory tract bacteria, were used to evaluate the specificity of DO-RAP. A total of 78 sputum specimens were simultaneously detected using DO-RAP, quantitative PCR (qPCR) and sanger sequencing of nested PCR products. Sanger sequencing results were used as the standard to verify the clinical performance of DO-RAP.

The reaction time of DO-RAP was less than 1 h. The sensitivity of DO-RAP was 2 copies/reaction, which was 10 times higher than qPCR. The sensitivity of DO-RAP for detecting heterogenous resistance was 5%. There was no cross-reactivity between the isoniazid wild-type gene, drug-resistant mutant genes, and other common respiratory tract bacteria. Compared with Sanger sequencing, the sensitivity, specificity, PPV and NPV of DO-RAP were all 100%. There were 7 specimens with gray zone or negative qPCR results but positive DO-RAP test results.

The DO-RAP can be adopted in ordinary qPCR equipment for the rapid, highly sensitive and specific detection of the isoniazid resistance genes of Mycobacterium tuberculosis.

The acquisition of isoniazid (INH) resistance is alarming, considering its importance as a key drug that forms the core of multidrug treatment regimens for tuberculosis (TB). Genetic mutations in the katG and inhA promoter regions play crucial roles in INH resistance, but their prevalence varies geographically. This study aimed to identify the most common mutations in the katG and inhA genes in INH-resistant (INH-R) Mycobacterium tuberculosis (MTB) clinical isolates in Cameroon. The research also explored the relationships between these mutations and patients' demographics (age, sex, and sample type).

We conducted a retrospective cross-sectional laboratory-based study on 500 INH-R isolates (with or without resistance to other first-line drugs) at the National Tuberculosis Reference Laboratory (NTRL) in Cameroon between January 2014 and December 2020. GenoType MTBDRplus assay was performed on the retrieved isolates and the frequency of katG and inhA mutations were calculated. Chi-square tests were utilized to assess the associations between these mutations and patients' age, sex and sample type.

A total of 410 (85.8%) culture-positive MTB isolates were analyzed, with a male-to-female ratio of 228 (55.6%) to 182 (44.4%) and an average age of 36.3 ± 13.4 years. Mutations in the katG and inhA genes were detected in 354 (86.3%) of cases, while 56 (13.7%) showed no mutations. Among the INH-R isolates, mutations in katG, inhA, and dual katG and inhA genes were present in 247 (60.2%), 76 (18.5%), and 31 (7.6%) isolates, respectively. Our analysis revealed significant associations between mutation prevalence and patient characteristics.

This study reaffirmed the importance of the katG S315T substitution as a key indicator of INH resistance, with the inhA C-15T mutation providing additional support. However, a notable proportion of isoniazid-resistant isolates did not exhibit these mutations, underscoring the need to comprehend resistance mechanisms. Given that these mechanisms are strongly associated with varying levels of INH resistance, it is crucial that TB management strategies incorporate genetic profiling alongside patient demographics to optimize treatment outcomes and enhance control measures.

Efficient management of drug-resistant tuberculosis relies on fast diagnostics. To accelerate phenotypic drug susceptibility testing [pDST] for Mycobacterium tuberculosis [TB], we introduce TRACeR-TB, a test that infers drug resistance from antibiotic-specific mRNA biomarkers.

To develop TRACeR-TB, target genes were first identified through RNA sequencing experiments conducted on two drug-exposed, susceptible strains for four antitubercular drugs. Based on these findings, we designed drug-specific multiplex Quantigene panels to quantify mRNA levels of 8-9 biomarkers per drug (class), directly from crude cell lysates. The performance of TRACeR-TB was compared to the widely used Mycobacteria Growth Indicator Tube [MGIT] pDST by subjecting 238 strains with diverse drug resistance profiles to both methods, and aligning results to genotypic data. Furthermore, we explored TRACeR-TB's potential for evaluating molecules that enhance antibiotic efficacy, and investigated its applicability in macrophage models to assess Mtb's intracellular stress responses to drugs.

Antituberculosis drugs trigger distinct transcriptional stress responses in susceptible, but not resistant bacilli, enabling a differentiation of the antibiotic phenotype in only 6 h. Validation on 238 strains showed TRACeR-TB had 100% (95% CI: 93·1-100%) sensitivity and 89·5% (95% CI: 74·7-97·2%) specificity compared to, respectively, 82·3% (95% CI: 69·2%-91·5%) and 94·8% (95% CI: 81·9%-99·4%) for MGIT pDST. TRACeR-TB specificity is likely underestimated due to the inclusion of isolates harbouring uncharacterised mutations. TRACeR-TB demonstrated 100% concordance with MGIT for drugs with reliable MGIT outcomes (moxifloxacin and isoniazid). Additionally, its sensitivity outperformed current rifampicin testing, detecting resistance in all borderline-resistant strains that MGIT missed, and bedaquiline testing. Furthermore, the assay detected the predicted effect of a novel drug booster and the intracellular drug-induced stress in macrophage models, highlighting its potential for drug optimisation.

TRACeR-TB is a complementary addition to current DSTs and can have a substantial impact on the TB diagnostics field. This tool can also play a vital role in identifying resistance mutations, thereby closing gaps in genotypic knowledge, and contribute to drug discovery and development.

Institut Pasteur, Agence Nationale de la Recherche.

This study leverages the Bacterial and Viral Bioinformatics Resource Center (BV-BRC) to analyze over 27,000 Mycobacterium tuberculosis (MTB) genomic strains, providing a comprehensive and large-scale overview of antibiotic resistance (AMR) prevalence and resistance patterns. We used MTB++, which is the newest and most comprehensive AI-based MTB drug resistance profiler tool, to predict the resistance profile of each of the 27,000 MTB isolates and then used feature analysis to identify key genes that were associated with the resistance. There are three main contributions to this study. Firstly, it provides a detailed picture of the prevalence of specific AMR genes in the BV-BRC dataset as well as their biological implications, providing critical insight into MTB's resistance mechanisms that can help identify genes of high priority for further investigation. The second aspect of this study is to compare the prevalence of antibiotic resistance across previous studies that have addressed both the temporal and geographical evolution of MTB drug resistance. Lastly, this study emphasizes the need for targeted diagnostics and personalized treatment plans. In addition to these contributions, the study acknowledges the limitations of computational prediction and recommends future experimental validation.

Tuberculosis (TB) remains a major global threat, with 10 million new cases and 1.5 million deaths each year. In multidrug-resistant tuberculosis (MDR-TB), resistance is most commonly observed against isoniazid (INH) and rifampicin (RIF), the two frontline drugs. Isoniazid resistance is predominantly linked to mutations in the InhA gene, which encodes an enzyme involved in mycolic acid synthesis, a vital component of the mycobacterial cell wall. Mutations in InhA reduce drug binding, rendering INH ineffective. These morbidity and mortality figures, along with the fact that the rise and global spread of drug-resistant TB, underscores the need for the discovery of novel therapeutics. In this direction, we have previously synthesized, characterized, and screened a library of diaryl ether dehydrozingerone derivatives against mycobacteria and identified two best hits, 7 and 14, based on bacteriostatic activities. The present study aimed to thoroughly investigate the antituberculosis potential of these compounds, particularly regarding drug-resistant TB. Our findings revealed that both compounds exhibited tuberculocidal activity against the standard laboratory strain Mycobacterium tuberculosis (M. tb) H37Rv, with minimal bactericidal concentrations (MBC) of 4μg/ml for compound 7 and 8 μg/ml for compound 14. Next, concentration vs time-kill kinetics of both these compounds showed concentration-dependent bactericidal activities against M. tb and complete pathogen eradication from culture at just 16× MIC. Both compounds were found to be suitable for combination regimens as their interactions with isoniazid and rifampicin against M. tb were observed to be synergistic. Additionally, 7 and 14 exhibited minimal hemolysis against human RBCs and less cytotoxicity was observed against three human cell lines up to 1000 μM. Molecular docking revealed that these compounds bind more effectively to M. tb InhA, including its mutant forms where isoniazid binding is impaired, outperforming both isoniazid and triclosan in binding affinity. Importantly 7 and 14 showed potent activity against drug-susceptible clinical isolates and two isoniazid-resistant M. tb clinical isolates equivalent to that against M. tb H37Rv. The most interesting observation was that both compounds were found to be effective against three multi-drug resistant (MDR) strains of M. tb, thereby depicting their potential against drug-resistant TB. An ex vivo assay on RAW 264 cells infected with M. tb demonstrated a significant reduction in bacterial load at 8× MIC, revealing the fact that these compounds are highly effective against intracellular M. tb H37Rv. To the best of our knowledge, this is the first study that reports promising antimycobacterial potential of 7 and 14 against drug-susceptible, isoniazid-resistant, and MDR tuberculosis which warrants further exploration considering the need for new anti-TB medicine.

Mycobacterium tuberculosis infections continue to pose a significant global health challenge, particularly due to the rise of multidrug-resistant strains, random mycobacterial mutations, and the complications associated with short-term antibiotic regimens. Currently, five approved drugs target cell wall biosynthesis in Mycobacterium tuberculosis. This review provides a comprehensive analysis of these drugs and their molecular mechanisms. Isoniazid, thioamides, and delamanid primarily disrupt mycolic acid synthesis, with recent evidence indicating that delamanid also inhibits decaprenylphosphoryl-β-D-ribose-2-epimerase, thereby impairing arabinogalactan biosynthesis. Cycloserine remains the sole approved drug that inhibits peptidoglycan synthesis, the foundational layer of the mycobacterial cell wall. Furthermore, ethambutol interferes with arabinogalactan synthesis by targeting arabinosyl transferase enzymes, particularly embB- and embC-encoded variants. Beyond these, six promising molecules currently in Phase II clinical trials are designed to target arabinan synthesis pathways, sutezolid, TBA 7371, OPC-167832, SQ109, and both benzothiazinone derivatives BTZ043 and PBTZ169, highlighting advancements in the development of cell wall-targeting therapies.

Globally, drug-resistant tuberculosis (DR-TB) is responsible for 13% of mortality attributable to antimicrobial resistance. In Ethiopia, extrapulmonary tuberculosis (EPTB) is a significant public health challenge, and drug resistance (DR) in EPTB is often overlooked. In a cross-sectional study conducted between August 2022 and October 2023, we aimed to explore the magnitude of phenotypic drug resistance and identify genetic mutations linked to resistance using 189 Mycobacterium tuberculosis (MTB) isolates cultured from extrapulmonary clinical specimens. Additionally, we assessed the agreement of the phenotypic and whole genome sequencing (WGS) based genotypic drug resistance detection. We performed phenotypic drug sensitivity testing (pDST) using liquid culture BD BACTECTM MGITTM 960 system and WGS using Illumina NextSeq500/550. The genomic data analysis pipelines MTBSeq and TBProfiler were used to predict drug resistance-conferring mutations. The agreement between the pDST and WGS was analyzed using SPSS version 29.0 software. Our result demonstrated phenotypic resistance to at least one anti-TB drug was detected in 16.9% (32/189) of the study participants. Isoniazid-resistant rifampicin-susceptible-TB (Hr-TB) and multi-drug-resistant TB (MDR-TB) phenotypes accounted for 2.6% (5/189) and 4.2% (8/189) respectively. Prevalence of MDR-TB was 2.4% (4/170) among newly diagnosed and 21.1% (4/19) among previously treated cases. WGS identified more (14/160, 8.75%) rifampicin-resistant genotypes (RR-TB) compared to pDST (8/189, 4.2%). We have identified a putative compensatory mutation for rifampicin (rpoBSer450Leu, rpoCAsp747Ala) for the first time from an EPTB clinical specimen in Ethiopia. Overall, there was a 3.75% rifampicin mono-resistant-TB(RMR-TB) genotype, which remains undetected using the conventional pDST and represented 42.9% (6/14) of the identified RR-TB genotypes. Mutations conferring rifampicin resistance-interim (rpoB.Ser450Ala) represented the majority (83.3%) of RMR-TB. Changes in ethA genes associated with ethionamide resistance were the most common resistance (n=7, 87.5%) in MDR-TB cases. There was a strong agreement between the pDST and WGS-TB Profiler pipeline to detect RR-TB (kappa=0.8) compared to the MTBSeq pipeline (k=0.58). In conclusion, MDR-TB, Hr-TB, and interim-RMR-TB are equally important public health challenges in the realm of EPTB in Ethiopia. The role of WGS is tremendous in detecting borderline/interim RMR-TB, which will help for tailored, personalized treatment strategies.

The current study aims to understand the resistance of Bifidobacterium adolescentis to different anti-tubercular drugs (first-line oral tuberculosis drugs). The bacteria were grown with anti-tubercular drugs such as isoniazid, pyrazinamide, and streptomycin to better understand the resistance phenomena. It was found that even at tenfold higher concentrations, growth rates remained unchanged. In addition, a small number of bacteria were found to aggregate strongly, a property that protects against the toxicity of the drug. Further FE-SEM (Field Emission Scanning Electron Microscopy) analysis revealed that some bacteria became excessively long, elongated, and protruded on the surface. Size scattering analysis confirmed the presence of bifidobacteria in the size range of 1.0-100 μm. After whole genome sequence analysis, certain mutations were found in the relevant gene. In vitro, foam formation and growth in the presence of H2O2 and HPLC (High Performance Liquid Chromatography) studies provide additional evidence for the presence of catalase. According to RAST (Rapid Annotation Using Subsystems Technology) annotation and CARD (Comprehensive Antibiotic Resistance Database analysis), there were not many components in the genome that were resistant to antibiotics. Whole genome sequence (WGS) analysis does not show the presence of bacteriocins and antibiotic resistance genes, but few hypothetical proteins were observed. 3D structure and docking studies suggest their interaction with specific ligands.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), continues to pose a significant global health threat. Identifying new druggable targets is crucial for the advancement of drug development. Equally critical is the development of precise methods for monitoring Mtb to effectively combat this disease. Addressing these needs, our study pinpointed the pore domain (PD) of MtbMmpL3 as a new binding site for virtual screening, which led to the discovery of the small molecule ZY27. To confirm the binding site and action mode of ZY27, we employed cosolvent molecular dynamics (CMD), steered molecular dynamics (SMD), and long timescale molecular dynamics (MD) simulations of 5 μs. These in silico studies verified that ZY27 binds to the PD of MtbMmpL3. In antimicrobial activity tests, ZY27 exhibited potent anti-Mtb activity and high selectivity among mycobacterial species. Whole-genome sequencing of spontaneous ZY27-resistant Mtb variants, complemented by acid-fast staining experiments, confirmed that ZY27 specifically targets MtbMmpL3. Utilizing the ligand-protein binding data, we designed and synthesized two solvatochromic fluorescent probes, 27FP1 and 27FP2, based on ZY27. Further investigations through flow cytometry and confocal microscopy confirmed that these probes specifically label Mtb cells via the MtbMmpL3 binding mechanism.

In previous studies, we demonstrated the potent activity of a library of 25 N,N'-disubstituted diamines (NNDDA) toward Trypanosomatid and Apicomplexa parasites. Considering the structure similarity between this collection and SQ109, an antituberculosis compound, and its compelling antiparasitic properties, we aimed to repurpose this library for tuberculosis treatment. We assayed this collection against Mycobacterium tuberculosis H37Rv and M. avium, obtaining several compounds with MIC values below 10 µM. The most active analogs were also evaluated against M. smegmatis, a non-pathogenic species, and the non-tuberculosis mycobacteria M. abscessus, M. kansasii, and M. fortuitum. 3c stands out as the lead mycobacterial compound of the collection, with potent activity against M. tuberculosis (minimal inhibitory concentration [MIC] = 3.4 µM) and moderate activity against M. smegmatis, M. kansasii, and M. fortuitum (all with MIC values of 26.8 µM). To unravel the mechanism of action, we employed the web-based platform Polypharmacology Browser 2 (PPB2), obtaining carbonic anhydrases as potential drug targets. Nevertheless, none of the compounds displayed experimental inhibition. In summary, our study confirms the validity of the repurposing approach and underscores the antimycobacterial potential of NNDDA compounds, especially the analog 3c, setting a stepping stone for further studies.

CRISPR-dead Cas9 interference (CRISPRi) has become a valuable tool for precise gene regulation. In this study, CRISPRi was designed to target the inhA gene of Mycobacterium smegmatis (Msm), a gene necessary for mycolic acid synthesis. Our findings revealed that sgRNA2 induced with 100 ng/ml aTc achieved over 90% downregulation of inhA gene expression and inhibited bacterial viability by approximately 1,000-fold. Furthermore, CRISPRi enhanced the susceptibility of M. smegmatis to isoniazid and rifampicin, which are both 50% and 90% lower than those of the wild-type strain or other strains, respectively. This study highlights the ability of CRISPRi to silence the inhA gene, which impacts bacterial viability and drug susceptibility. The findings provide valuable insights into the utility of CRISPRi as an alternative tool for gene regulation. CRISPRi might be further assessed for its synergistic effect with current anti-tuberculosis drugs and its possible implications for combating mycobacterial infections, especially drug-resistant tuberculosis.

Tuberculosis (TB) represents a global public health threat and is a leading cause of morbidity and mortality worldwide. Effective control of TB is complicated with the emergence of multidrug resistance. Yet, there is a fundamental gap in understanding the complex and dynamic interactions between different Mycobacterium tuberculosis strains and the host. In this pilot study, we investigated the host immune response to different M. tuberculosis strains, including drug-sensitive avirulent or virulent, and rifampin-resistant or isoniazid-resistant virulent strains in human THP-1 cells. We identified major differences in the gene expression profiles in response to infection with these strains. The expression of IDO1 and IL-1β in the infected cells was stronger in all virulent M. tuberculosis strains. The most striking result was the overexpression of many interferon-stimulated genes (ISGs) in cells infected with the isoniazid-resistant strain, compared to the rifampin-resistant and the drug-sensitive strains. Our data indicate that infection with the isoniazid-resistant M. tuberculosis strain preferentially resulted in cGAS-STING/STAT1 activation, which induced a characteristic host immune response. These findings reveal complex gene signatures and a dynamic variation in the immune response to infection by different M. tuberculosis strains.

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.

Few studies in routine settings have confirmed the high accuracy of the Xpert MTB/RIF assay for detecting rifampicin resistance (RR) and the first-line probe assay (FL-LPA) for detecting both RR and isoniazid resistance (INHR).

The performance of Xpert MTB/RIF and MTBDRplus VER 2.0 LPA was evaluated in 180 Mycobacterium tuberculosis samples collected from January 2018 to December 2019 in Rio de Janeiro, Brazil. The results were compared with those from BACTEC MGIT 960 culture and drug susceptibility testing (DST). Whole-genome sequencing was performed on the samples with discordant results.

The Xpert MTB/RIF assay showed a sensitivity (Se) of 93.3% and a specificity (Sp) of 97.6%, detecting RR. The performance of FL-LPA to identify RIF and INH resistance was, respectively, (Se) 100% and 83.3% and (Sp) 98.8% and 100%. Among 18 clinical isolates with INHR detected by FL-LPA, mutations in the katG gene were observed in 100% of samples, of which only two (11.1%) had mutations in both katG and inhA genes. Overall, the discordant results were identified in 9 (5%) samples. Among the four Xpert RIF-resistant and DST-sensitive, two harbored mutations in rpoB Leu430Pro. Among the four FL-LPA-sensitive and DST-resistant, one had a mutation in inhA 17G>T. FL-LPA showed high accuracy in detecting RR and INHR.

The MTBDRplus test demonstrated excellent performance in detecting RR, and INHR in clinical isolates under routine conditions at a reference laboratory in Rio de Janeiro, Brazil. Incorporating both tests can improve drug-resistant tuberculosis treatment outcomes and monitor the INHR incidence.

Due to interindividual variability in drug metabolism and pharmacokinetics, traditional isoniazid fixed-dose regimens may lead to suboptimal or toxic isoniazid concentrations in the plasma of patients with tuberculosis, contributing to adverse drug reactions, therapeutic failure, or the development of drug resistance. Achieving precision therapy for isoniazid requires a multifaceted approach that could integrate various clinical and genomic factors to tailor the isoniazid dose to individual patient characteristics. This includes leveraging molecular diagnostics to perform the comprehensive profiling of host pharmacogenomics to determine how it affects isoniazid metabolism, such as its metabolism by N-acetyltransferase 2 (NAT2), and studying drug-resistant mutations in the Mycobacterium tuberculosis genome for enabling targeted therapy selection. Several other molecular signatures identified from the host pharmacogenomics as well as other omics-based approaches such as gut microbiome, epigenomic, proteomic, metabolomic, and lipidomic approaches have provided mechanistic explanations for isoniazid pharmacokinetic variability and/or adverse drug reactions and thereby may facilitate precision therapy of isoniazid, though further validations in larger and diverse populations with tuberculosis are required for clinical applications. Therapeutic drug monitoring and population pharmacokinetic approaches allow for the adjustment of isoniazid dosages based on patient-specific pharmacokinetic profiles, optimizing drug exposure while minimizing toxicity and the risk of resistance. Current evidence has shown that with the integration of the host pharmacogenomics-particularly NAT2 and Mycobacterium tuberculosis genomics data along with isoniazid pharmacokinetic concentrations in the blood and patient factors such as anthropometric measurements, comorbidities, and type and timing of food administered-precision therapy approaches in isoniazid therapy can be tailored to the specific characteristics of both the host and the pathogen for improving tuberculosis treatment outcomes.

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb), which remains a significant global health challenge. The emergence of multidrug-resistant (MDR) Mtb strains imposes the development of new therapeutic strategies. This study focuses on the identification and evaluation of potential inhibitors against Mtb H37Ra through a comprehensive screening of an in-house chemolibrary. Subsequently, a promising pyrimidine derivative (LQM495) was identified as promising and then further investigated by experimental and in silico approaches. In this context, computational techniques were used to elucidate the potential molecular target underlying the inhibitory action of LQM495. Then, a consensus reverse docking (CRD) protocol was used to investigate the interactions between this compound and several Mtb targets. Out of 98 Mtb targets investigated, the enhanced intracellular survival (Eis) protein emerged as a target for LQM495. To gain insights into the stability of the LQM495-Eis complex, molecular dynamics (MD) simulations were conducted over a 400 ns trajectory. Further insights into its binding modes within the Eis binding site were obtained through a Quantum mechanics (QM) approach, using density functional theory (DFT), with B3LYP/D3 basis set. These calculations shed light on the electronic properties and reactivity of LQM495. Subsequently, inhibition assays and kinetic studies of the Eis activity were used to investigate the activity of LQM495. Then, an IC50 value of 11.0 ± 1.4 µM was found for LQM495 upon Eis protein. Additionally, its Vmax, Km, and Ki parameters indicated that it is a competitive inhibitor. Lastly, this study presents LQM495 as a promising inhibitor of Mtb Eis protein, which could be further explored for developing novel anti-TB drugs in the future.

This study aimed to investigate the antibacterial effects of plasma-activated saline (PAS) on My-cobacterium tuberculosis (Mtb).

We conducted a growth assay on 3 strains of Mtb and an antibiotic sensitivity test on 4 strains of Mtb. Both tests included groups treated with normal saline (NS), PAS, and hydrochloric acid (HCl). The test of antibiotic sensitivity consisted of parallel tests with two concentrations of bacteria suspension: 10-2 and 10-4. The selected antibiotics were rifampicin (RIF), isoniazid (INH), ethambutol (EMB), and streptomycin (SM). The number of bacteria was determined after one month of culture under different conditions. The Kruskal-Wallis test was used to analyze the differences in grouping factors at representative time points.

The growth assay indicated that PAS significantly inhibited the growth of 3 strains of Mtb compared with NS and HCl treatment groups. Furthermore, except for the initial observation time point, the remaining three observation time points consistently demonstrate no significant differences between the NS group and the HCl group. The antibiotic sensitivity test of INH, SM, and RIF indicated that PAS could inhibit the growth of antibiotic-resistant Mtb, and the antibiotic sensitivity test of INH and SM with bacterial suspension concentration of 10-2 and SM with bacterial suspension concentration of 10-4 showed statistically different results. The antibiotic sensitivity test of EMB indicated that the growth of Mtb in PAS was slower than that in NS and HCl in both antibiotic-resistant and sensitive Mtb, but there was no statistical difference.

The study indicates that PAS contains a significant amount of active substances and exhibits high oxidizability and an acidic pH state. The unique physicochemical properties of PAS significantly delayed the growth of Mtb, compared to the NS and the HCl. PAS not only inhibited the growth of drug-sensitive strains but also significantly enhanced the sensitivity of drug-resistant strains to anti-tuberculosis drugs, which may provide a new therapeutic strategy for the treatment of tuberculosis.

Tuberculosis (TB) stands as the second most prevalent cause of global human mortality from infectious diseases. In 2022, the World Health Organization documented an estimated number of global TB cases reaching 7.5 million, which causes death for 1.13 million patients. The continuous growth of drug-resistant TB cases due to various mutations in the Mycobacterium tuberculosis (MTB) strain, raises the urgency of the exploration of novel anti-TB treatments. Ursolic acid (UA) is a natural pentacyclic triterpene found in various plants that has shown potential as a novel anti-TB agent. This review aims to provide an overview of the therapeutic prospects of UA against MTB, with a particular emphasis on in silico, in vitro, and in vivo studies. Various mechanisms of action of UA against MTB are briefly recapped from in silico studies, such as enoyl acyl carrier protein reductase inhibitors, FadA5 (Acetyl-CoA acetyltransferase) inhibitors, tuberculosinyl adenosine transferase inhibitors, and small heat shock protein 16.3 inhibitor. The potential of UA to overcome drug resistance and its synergistic effects with existing antituberculosis drugs are briefly explained from in vitro studies using a variety of methods, such as Microplate Alamar Blue Assay, Mycobacteria Growth Indicator Tube 960 and Resazurin Assays, morphological change evaluation using transmission electron microscopy, and in vivo studies using BALB/C infected with multi drug resistant clinical isolates. Besides its promising mechanism as an antituberculosis drug, its complex chemical composition, limited availability and supply, and lack of intellectual property are also reviewed as those are the most frequently occurring challenges that need to be addressed for the successful development of UA as novel anti-TB agent.

Multidrug-resistant tuberculosis (MDR-TB) has posed a serious threat to global public health, and antimicrobial peptides (AMPs) have emerged to be promising candidates to tackle this deadly infectious disease. Previous study has suggested that two AMPs, namely D-LAK120-A and D-LAK120-HP13, can potentiate the effect of isoniazid (INH) against mycobacteria. In this study, the strategy of combining INH and D-LAK peptide as a dry powder formulation for inhalation was explored. The antibacterial effect of INH and D-LAK combination was first evaluated on three MDR clinical isolates of Mycobacteria tuberculosis (Mtb). The minimum inhibitory concentrations (MICs) and fractional inhibitory concentration indexes (FICIs) were determined. The combination was synergistic against Mtb with FICIs ranged from 0.25 to 0.38. The INH and D-LAK peptide at 2:1 mole ratio (equivalent to 1: 10 mass ratio) was identified to be optimal. This ratio was adopted for the preparation of dry powder formulation for pulmonary delivery, with mannitol used as bulking excipient. Spherical particles with mass median aerodynamic diameter (MMAD) of around 5 µm were produced by spray drying. The aerosol performance of the spray dried powder was moderate, as evaluated by the Next Generation Impactor (NGI), with emitted fraction and fine particle fraction of above 70 % and 45 %, respectively. The circular dichroism spectra revealed that both D-LAK peptides retained their secondary structure after spray drying, and the antibacterial effect of the combination against the MDR Mtb clinical isolates was successfully preserved. The combination was found to be effective against MDR Mtb isolates with KatG or InhA mutations. Overall, the synergistic combination of INH with D-LAK peptide formulated as inhaled dry powder offers a new therapeutic approach against MDR-TB.

One of the biggest health challenges of today's world is the emergence of antimicrobial resistance (AMR), which renders conventional therapeutics insufficient and urgently demands the generation of novel antimicrobial strategies. Mycobacterium tuberculosis (M. tuberculosis), the pathogen causing tuberculosis (TB), is among the most successful bacteria producing drug-resistant infections. The versatility of M. tuberculosis allows it to evade traditional anti-TB agents through various acquired and intrinsic mechanisms, rendering TB among the leading causes of infectious disease-related mortality. In this context, researchers worldwide focused on establishing novel approaches to address drug resistance in M. tuberculosis, developing diverse alternative treatments with varying effectiveness and in different testing phases. Overviewing the current progress, this paper aims to briefly present the mechanisms involved in M. tuberculosis drug-resistance, further reviewing in more detail the under-development antibiotics, nanotechnological approaches, and natural therapeutic solutions that promise to overcome current treatment limitations.

Tuberculosis (TB), an infectious disease caused by Mycobacterium tuberculosis is one of the top ten causes of death worldwide. Isoniazid (INH) is an important component of anti-tuberculosis therapy (ATT). Low isoniazid levels can serve as a risk factor for the development of treatment failure, relapse of disease and acquired secondary resistance. Hence, serum level of isoniazid becomes a critical factor in determining the treatment outcome of patients on ATT. This study aimed to evaluate the correlation between serum isoniazid concentration and therapeutic response in patients of pulmonary tuberculosis in Central India.

This was a prospective single cohort observational study conducted at a tertiary care hospital. Therapeutic response in newly diagnosed patients of pulmonary TB was determined based the microbiological, clinical and radiological parameters. Serum INH levels were estimated based on a spectrophotometric method using nano-spectrophotometer.

In this study, patients had a significant improvement in treatment outcome as evident by a significant decrease in the TB score I at end of IP (p = 0.001) and a significant decline in the Timika score at end of CP (p = 0.001). Although all patients converted to sputum negative at end of CP, 20% remained positive at end of IP. Lower INH levels were seen in 13.3% of the study population. Higher INH levels were observed in sputum converters, patients with low TB score I and low Timika score, although no statistically significant difference was noted (p > 0.05).

In this study, we could not find any statistically significant association between serum INH levels and therapeutic outcome of the patients. Further studies on a larger population could provide better understanding about the prevalence of low serum isoniazid levels among the Indian population and establish its relationship with therapeutic outcome. Also, the usage of a comparatively less expensive spectrophotometric method of analysis makes this feasible in almost every district hospital without the need of high-performance liquid chromatography which is costlier and needs more expertise.

This study employed adaptive laboratory evolution to improve the acid tolerance of Lactiplantibacillus plantarum, a vital strain in food fermentation and a potential probiotic. Phenotype and genomic analyses identified the overexpression of stress response proteins, ATP synthases, and transporters as pivotal in conferring acid tolerance to the evolved strains. These adaptations led to a shorter lag phase, improved survival rates, and higher intracellular pH values compared to the wild-type strain under acid stress conditions. Additionally, the evolved strains showed an increased expression of genes in the fatty acid synthesis pathway, resulting in a higher production of unsaturated fatty acids. The changes in cell membrane composition possibly prevented H+ influx, while mutant genes related to cell surface structure contributed to observed elongated cells and thicker cell surface. These alterations in cell wall and membrane composition, along with improved transporter efficiency, were key factors contributing to the enhanced acid tolerance in the evolved strains.

Isoniazid-resistant tuberculosis (Hr-TB) is an important drug-resistant tuberculosis (TB). In addition to rifampicin, resistance to other medications for Hr-TB can impact the course of treatment; however, there are currently limited data in the literature. In this study, the drug susceptibility profiles of Hr-TB treatment and resistance-conferring mutations were investigated for Hr-TB clinical isolates from Thailand. Phenotypic drug susceptibility testing (pDST) and genotypic drug susceptibility testing (gDST) were retrospectively and prospectively investigated using the Mycobacterium Growth Indicator Tube (MGIT), the broth microdilution (BMD) method, and whole-genome sequencing (WGS)-based gDST. The prevalence of Hr-TB cases was 11.2% among patients with TB. Most Hr-TB cases (89.5%) were newly diagnosed patients with TB. In the pDST analysis, approximately 55.6% (60/108) of the tested Hr-TB clinical isolates exhibited high-level isoniazid resistance. In addition, the Hr-TB clinical isolates presented co-resistance to ethambutol (3/161, 1.9%), levofloxacin (2/96, 2.1%), and pyrazinamide (24/118, 20.3%). In 56 Hr-TB clinical isolates, WGS-based gDST predicted resistance to isoniazid [katG S315T (48.2%) and fabG1 c-15t (26.8%)], rifampicin [rpoB L430P and rpoB L452P (5.4%)], and fluoroquinolones [gyrA D94G (1.8%)], but no mutation for ethambutol was detected. The categorical agreement for the detection of resistance to isoniazid, rifampicin, ethambutol, and levofloxacin between WGS-based gDST and the MGIT or the BMD method ranged from 80.4% to 98.2% or 82.1% to 100%, respectively. pDST and gDST demonstrated a low co-resistance rate between isoniazid and second-line TB drugs in Hr-TB clinical isolates.

The prevalence of isoniazid-resistant tuberculosis (Hr-TB) is the highest among other types of drug-resistant tuberculosis. Currently, the World Health Organization (WHO) guidelines recommend the treatment of Hr-TB with rifampicin, ethambutol, pyrazinamide, and levofloxacin for 6 months. The susceptibility profiles of Hr-TB clinical isolates, especially when they are co-resistant to second-line drugs, are critical in the selection of the appropriate treatment regimen to prevent treatment failure. This study highlights the susceptibility profiles of the WHO-recommended treatment regimen in Hr-TB clinical isolates from a tertiary care hospital in Thailand and the concordance and importance of using the phenotypic drug susceptibility testing or genotypic drug susceptibility testing for accurate and comprehensive interpretation of results.

To evaluate the effectiveness and safety of Interferon-gamma release Assay (IGRA)-based isoniazid (INH) prophylaxis strategy to prevent tuberculosis (TB) infection in kidney transplantation (KT) with a risk of TB occurrence.

Adult KT recipients (KTRs) between June 2014 and July 2021 were retrospectively enrolled. The development of active TB after KT was evaluated.

Of 925 KTRs, 111 (12.0%) developed active TB. Among the 501 KTRs at a risk of TB occurrence, 70 (14.0%) patients developed active TB, while 41 (9.7%) of 424 patients without risk factors developed active TB (P = 0.05). Two hundred thirty-nine KTRs received IGRA test with 62 (25.9%) were positive. None of IGRA positive patients (0/40) receiving INH prophylaxis developed active TB, whereas 8 out of 22 patients who had positive IGRA results without INH prophylaxis developed active TB (0 vs. 36.4%, P < 0.01). Of note, for those in risk group but with negative IGRA result, no active TB was found even without INH prophylaxis. Although alanine aminotransferase and aspartate aminotransferase in INH prevention group were higher than those before treatment, they did not exceed three-fold of limit of reference range.

IGRA-based INH treatment is an effective and safe protocol to prevent the development of active TB in KTRs.

Mycobacterium tuberculosis (Mtb) is a pathogenic bacterium which causes tuberculosis (TB). TB control programmes are facing threats from drug resistance. Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mtb strains need longer and more expensive treatment with many medications resulting in more adverse effects and decreased chances of treatment outcomes. The World Health Organization (WHO) has emphasised the development of not just new individual anti-TB drugs, but also novel medication regimens as an alternative treatment option for the drug-resistant Mtb strains. Many plants, as well as marine creatures (sponge; Haliclona sp.) and fungi, have been continuously used to treat TB in various traditional treatment systems around the world, providing an almost limitless supply of active components. Natural products, in addition to their anti-mycobacterial action, can be used as adjuvant therapy to increase the efficacy of conventional anti-mycobacterial medications, reduce their side effects, and reverse MDR Mtb strain due to Mycobacterium's genetic flexibility and environmental adaptation. Several natural compounds such as quercetin, ursolic acid, berberine, thymoquinone, curcumin, phloretin, and propolis have shown potential anti-mycobacterial efficacy and are still being explored in preclinical and clinical investigations for confirmation of their efficacy and safety as anti-TB medication. However, more high-level randomized clinical trials are desperately required. The current review provides an overview of drug-resistant TB along with the latest anti-TB medications, drug-induced hepatotoxicity and oxidative stress. Further, the role and mechanisms of action of first and second-line anti-TB drugs and new drugs have been highlighted. Finally, the role of natural compounds as anti-TB medication and hepatoprotectants have been described and their mechanisms discussed.

Once hailed as miraculous solutions, antibiotics no longer hold that status. The excessive use of antibiotics across human healthcare, agriculture, and animal husbandry has given rise to a broad array of multidrug-resistant (MDR) pathogens, posing formidable treatment challenges. Antimicrobial resistance (AMR) has evolved into a pressing global health crisis, linked to elevated mortality rates in the modern medical era. Additionally, the absence of effective antibiotics introduces substantial risks to medical and surgical procedures. The dwindling interest of pharmaceutical industries in developing new antibiotics against MDR pathogens has aggravated the scarcity issue, resulting in an exceedingly limited pipeline of new antibiotics. Given these circumstances, the imperative to devise novel strategies to combat perilous MDR pathogens has become paramount. Contemporary research has unveiled several promising avenues for addressing this challenge. The article provides a comprehensive overview of these innovative therapeutic approaches, highlighting their mechanisms of action, benefits, and drawbacks.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a significant global health challenge, further compounded by the issue of antimicrobial resistance (AMR). AMR is a result of several system-level molecular rearrangements enabling bacteria to evolve with better survival capacities: metabolic rewiring is one of them. In this review, we present a detailed analysis of the metabolic rewiring of Mtb in response to anti-TB drugs and elucidate the dynamic mechanisms of bacterial metabolism contributing to drug efficacy and resistance. We have discussed the current state of AMR, its role in the prevalence of the disease, and the limitations of current anti-TB drug regimens. Further, the concept of metabolic rewiring is defined, underscoring its relevance in understanding drug resistance and the biotransformation of drugs by Mtb. The review proceeds to discuss the metabolic adaptations of Mtb to drug treatment, and the pleiotropic effects of anti-TB drugs on Mtb metabolism. Next, the association between metabolic changes and antimycobacterial resistance, including intrinsic and acquired drug resistance, is discussed. The review concludes by summarizing the challenges of anti-TB treatment from a metabolic viewpoint, justifying the need for this discussion in the context of novel drug discovery, repositioning, and repurposing to control AMR in TB.

To describe katG and inhA mutations, clinical characteristics, treatment outcomes and clustering of drug-resistant tuberculosis (TB) in the State of São Paulo, southeast Brazil.

Mycobacterium tuberculosis isolates from patients diagnosed with drug-resistant TB were screened for mutations in katG and inhA genes by line probe assay and Sanger sequencing, and typed by IS6110-restriction fragment-length polymorphism for clustering assessment. Clinical, epidemiological and demographic data were obtained from surveillance information systems for TB.

Among the 298 isolates studied, 127 (42.6%) were isoniazid-monoresistant, 36 (12.1%) polydrug-resistant, 93 (31.2%) MDR, 16 (5.4%) pre-extensively drug-resistant (pre-XDR), 9 (3%) extensively drug-resistant (XDR) and 17 (5.7%) susceptible after isoniazid retesting. The frequency of katG 315 mutations alone was higher in MDR isolates, while inhA promoter mutations alone were more common in isoniazid-monoresistant isolates. Twenty-six isolates phenotypically resistant to isoniazid had no mutations either in katG or inhA genes. The isolates with inhA mutations were found more frequently in clusters (75%) when compared to the isolates with katG 315 mutations (59.8%, p = 0.04). In our population, being 35-64 years old, presenting MDR-, pre-XDR- or XDR-TB and being a retreatment case were associated with unfavourable TB treatment outcomes.

We found that katG and inhA mutations were not equally distributed between isoniazid-monoresistant and MDR isolates. In our population, clustering was higher for isolates with inhA mutations. Finally, unfavourable TB outcomes were associated with specific factors.