Tuberculosis

BackgroundBovine tuberculosis (bTB) is a chronic infectious disease primarily caused by Mycobacterium bovis, which inflicts significant economic losses on the global livestock industry worldwide and can also cause tuberculosis (TB) disease in other mammalian species, including humans. Alveolar macrophages are the host cells targeted by the pathogen during the early stages of infection. While they play a crucial role in controlling infection, the exact nature of the host-pathogen interaction and the genetic and epigenetic factors that modulate infection outcome remain poorly understood. ResultsHere, we used transcriptomics (RNA-seq) and chromatin configuration analyses (ChIP-seq and ATAC-seq) to examine the effects of intracellular mycobacterial infection on the bovine alveolar macrophage (bAM) transcriptome and epigenome. The primary focus was M. bovis infection, but we also conducted parallel comparative analyses using M. tuberculosis (the primary cause of human TB--hTB), M. bovis BCG (the vaccine strain), and gamma-irradiated (killed) M. bovis. Integration of RNA-seq, ChIP-seq, and ATAC-seq data revealed coordinated remodelling of chromatin accessibility and histone modification landscapes underpinning transcriptional activation of key immune and metabolic pathways in response to infection. The identification of candidate genes, including ERBB4, LRCH1, MRTFA, and RNPC3, through integrative analysis with a genome-wide association study (GWAS) for M. bovis infection susceptibility underscores the functional relevance of these regulatory networks. ConclusionsOur results demonstrate that M. bovis drives extensive reprogramming of the bAM epigenome, distinct from the responses elicited by other members of the M. tuberculosis complex (MTBC). The results of this multi-omics comparison provide new insights into the function of pivotal response genes and support the hypothesis that pathogen-driven epigenetic reprogramming of the bovine host macrophage is key to M. bovis survival. It also identifies molecular targets that may inform genome-enabled breeding strategies to enhance bTB disease resilience in cattle.

RATIONALEThe host-protective role of alpha-1-antitrypsin (AAT) against mycobacteria may be partly attributed to its binding to the cytoplasmic glucocorticoid receptor (GR) that results in gene regulation in macrophages that favors killing of ingested mycobacteria. The AAT-GR complex was found to be significantly responsible for limiting Mycobacterium avium complex (MAC) burden in macrophages; this host-protective function of AAT-GR is due, in part, to induction of COLONY STIMULATING FACTOR-2 (CSF-2) gene which encodes for granulocyte-monocyte colony stimulating factor (GM-CSF). METHODSTo better understand the role of AAT-GR binding during mycobacterial infection, we performed bulk RNA sequencing (RNA-seq) on four different groups of cells: (i) control THP-1 cells (THP-1control); (ii) THP-1control cells infected with Mycobacterium intracellulare (MAC); (iii) THP-1control cells incubated with MAC + AAT; and (iv) THP-1 cells knocked down for GR (THP-1GR-KD) incubated with MAC + AAT. RESULTSOur analyses revealed that MAC infection significantly upregulated 1,977 genes and significantly downregulated 2,303 genes in THP-1control cells. Additionally, AAT significantly upregulated 1,200 genes and downregulated 890 genes in MAC-infected THP-1control cells. Furthermore, the regulation of 1,624 genes that are regulated by AAT+GR in THP-1control cells was augmented in THP-1GR-KD cells, indicating that the regulation of these genes by AAT+MAC is inhibited by GR. Conversely, the regulation of 1,683 genes by AAT+MAC in THP-1control cells was attenuated in THP-1GR-KD cells, indicating that the regulation of these genes by AAT+MAC is enhanced by GR. MAC also induced both CSF2 (GM-CSF) and CSF1 (encodes for monocyte colony stimulating factor, M-CSF) expression. Whereas AAT inhibited MAC-induced M-CSF mRNA was dependent on GR, this inhibition of M-CSF protein was not dependent on GR. In contrast, AAT did not inhibit MAC-induced CSF2 (GM-CSF) expression. Since either MAC or AAT induced GM-CSF expression in macrophages, further investigation revealed that AAT-inhibition of cell-associated MAC burden was abrogated upon neutralization of endogenous GM-CSF. CONCLUSIONSThe ability of AAT to induce GM-CSF and to inhibit MAC-induced M-CSF may skew macrophages to a phenotype that is better endowed to control mycobacterial infection.

IntroductionPredictive biomarkers for symptomatic tuberculosis (TB) progression would transform targeted prevention efforts. Although interferon-gamma release assays (IGRAs), including QuantiFERON(R) TB-Gold Plus (QFT-Plus), have been studied for this purpose, systematic evaluation of the QFT-Plus TB1 and TB2 Interferon-Gamma (IFN{gamma}) concentrations remains limited, particularly in high-burden TB settings. MethodsBaseline TB1 and TB2 IFN{gamma} concentrations from 5,259 participants in TB-endemic regions were analyzed in relation to subsequent TB outcomes over a median of 525 days follow-up. Participants were categorized as controls (no TB), suspected TB (no microbiological confirmation), or laboratory-confirmed TB, including a subset meeting a stringent case definition ([&ge;]2 positive microbiologic tests). Associations between baseline IFN{gamma} concentrations and progression to symptomatic TB were assessed. ResultsIn the full cohort (IGRA+/-participants), baseline TB2 IFN{gamma} concentrations were significantly higher compared to controls among participants who developed suspected TB (p=0.01), laboratory-confirmed TB (p=0.01), or met the stringent case definition (p<0.0001). In IGRA+ participants, baseline TB2 concentrations were significantly higher than controls in suspected (p=0.01) and laboratory-confirmed (p=0.02) groups. Associations with baseline TB1 IFN{gamma} concentrations and TB progression were observed for participants meeting the stringent case definition within the full cohort (p=0.009). Among stringent definition cases, TB2 concentrations achieved an area under the Receiver Operating Characteristic curve of 0.84, with a sensitivity of 80% and specificity of 78%. ConclusionsQuantitative IFN{gamma} concentrations from QFT-Plus, particularly TB2, were associated with progression to symptomatic TB, met or exceeded WHO-recommended sensitivity and specificity thresholds for predictive biomarkers, and may support biomarker-based stratification in TB clinical research. SummaryIn an exploratory analysis from a global tuberculosis (TB) epidemiology study, higher QuantiFERON-TB Gold Plus IFN{gamma} concentrations were associated with progression to symptomatic TB and met WHO predictive biomarker thresholds, supporting their potential value for risk stratification in TB research.

Intravital microscopy enables direct visualization of dynamic cellular processes within intact tissues, but its application to Mycobacterium tuberculosis (Mtb) has been limited by Biosafety Level 3 (BSL-3) containment requirements and the technical challenges of stabilizing the lung for high-resolution imaging. Here, we present a protocol that combines the thoracic Window for High-Resolution Imaging of the murine Lung (WHRIL) with a genetically defined, triple-auxotrophic Mtb strain (mc27902) approved for use under BSL-2 conditions. We describe the construction of a tdTomato-expressing derivative (mc28471) preparation of bacteria for intravenous infection and intravital imaging in reporter mice. This system enables visualization of rapid bacterial entry into the pulmonary vasculature, subsequent aggregation, and vascular occlusion, dissemination into the lung parenchyma, and macrophage uptake over three days post-infection. This protocol provides the first practical platform for real-time intravital imaging of mycobacteria in the lung and establishes a foundation for mechanistic studies of bacterial physiology, host recognition, and immune-mediated clearance using safe Mtb surrogates. SummaryThis protocol describes a biosafety level 2 (BSL-2)-compatible intravital imaging platform for visualizing Mycobacterium tuberculosis (Mtb) in the intact murine lung at single cell resolution. By combining the Window for High-Resolution Imaging of the murine Lung (WHRIL) with a fluorescently labeled, genetically defined triple auxotrophic Mtb strain (mc27902), this approach overcomes long-standing biosafety and technical barriers that have prevented real-time imaging of mycobacterial infection in vivo. The method enables direct visualization of early bacterial localization, aggregation, vascular interactions, and macrophage uptake during the initial hours to days following infection, providing a practical foundation for mechanistic studies of host-pathogen interactions under safe experimental conditions.

Bedaquiline resistance is emerging globally and threatens the effectiveness of the novel short all-oral regimens for rifampicin-resistant tuberculosis. Following a systematic literature review, we quantified 13 sequence, biochemical, and structural features of 62 Rv0678 missense variants reported in 136 Mycobacterium tuberculosis isolates. Using rigorous machine learning methods, we show that the strongest contributing features were the evolutionary conservation score and the shortest atomic distance to key functional sites. The final 5-feature model had good performance (ROC-AUC 0.826) and classified the bedaquiline phenotype with high accuracy [sensitivity 87.1% (95% CI, 78.3-92.6) and specificity 88.2% (95% CI, 76.6-94.5)]. Performance was lower in external validation, likely due to the measurement error introduced when using diverse phenotypic methods. missense variants on the mmpR5 protein structure and function. Integrating the five-feature in-silico in variant interpretation software could improve the prediction of the effect of Rv0678 variants and guide clinical management of rifampicin-resistant tuberculosis.

BackgroundTuberculosis (TB) remains a major global health concern, posing a substantial burden in Pakistan. Genetic factors play a pivotal role in individual susceptibility to TB. Surfactant protein A and surfactant protein D are essential components of the innate immune system, contributing to pulmonary host defense against Mycobacterium tuberculosis (MTB). AimThis study aimed to investigate the association between single nucleotide polymorphisms (SNPs) in the SP-A1gene at rs1059047 (+1101 C/T) and the SP-D gene at rs3088308 (911 T/A) and TB susceptibility in the Pakistani population. MethodA case-control study was conducted, comprising 350 individuals, including 150 healthy controls, 100 TB patients, and 100 TB contacts. Genotyping was performed using tetra ARMS-PCR. GraphPad Prism v.10 was used for statistical analysis. ResultsOur results revealed no significant association between the SP-A1 gene polymorphism at rs1059047 (+1101 C/T) and SP-D gene polymorphism at rs3088308 (911 T/A) and TB susceptibility in the Pakistani population (p>0.5). Interestingly, concerning the rs3088308 polymorphism in the SP-D gene, a comparison between healthy controls and TB contacts indicated that the homozygous TT genotype was significantly associated with protection against LTBI (73.53% vs. 82.35%; p=0.00, OR=0.19, 95% CI=0.08-0.51).

Recent studies suggested that human cytomegalovirus (HCMV) exposure may increase tuberculosis (TB) disease risk. We assessed the association between active HCMV infection and recent HCMV exposure with tuberculosis (TB) disease among TB-presumptive South African adults. This was a nested case-control analysis that utilized stored plasma and serum samples collected from adults ([&ge;]18 years) with presumptive TB self-presenting to primary care clinics in in the Kraaifontein District in Cape Town, South Africa. Cases (n=98) and HIV status frequency matched controls (n=199) basing on mycobacterial culture and or GeneXpert Ultra were included in the study. HCMV DNAemia was detected by qPCR well as current HCMV reactivation or reinfection and recent HCMV infection, reactivation or reinfection were categorized using PCR and serology (IgM and IgG avidity ELISA) results. The median age of all participants was 37 years (IQR 29-47), 164 (55.2%) were male and 119 (40.1%) had previous TB treatment. Overall, 21 (7.1%) had HCMV DNAemia, 19 (6.4%) had positive HCMV IgM and 2 (0.7%) had low HCMV avidity. In a logistic regression model adjusting for age, gender, HIV status and BMI, TB disease was associated with current HCMV reactivation or reinfection [adjusted odds ratio (aOR) 4.88, 95%CI 1.59-16.31, p=0.007]. There was no association with recent HCMV infection, reactivation or reinfection. Unlike recent HCMV infection, reactivation or reinfection, active HCMV replication although not frequent was associated with TB disease which suggests that TB disease or an underlying common factor reactivates HCMV replication in this population.

Mycobacteria have a hydrophobic cell envelope that makes uniform growth in liquid culture challenging. Non-ionic detergents including Tween-80 and tyloxapol are commonly added to media when culturing mycobacterial species in the laboratory. Tyloxapol was reported to exhibit anti-tuberculous activity during animal infection with M. tuberculosis in the 1950s. In the 1980s, microscopy studies suggested that tyloxapol impacted the inter-action between M. tuberculosis and the phagosomal membrane, preventing mycobacterial access to the cytoplasm. It is now known that the ESX-1 Type VII secretion system mediates the interaction between pathogenic mycobacteria and the phagosomal membrane. Mycobacterium marinum is a pathogenic mycobacterial species that has been widely used to understand the molecular mechanisms and host responses to the ESX-1 system. The hemolytic activity of M. marinum allows the study of ESX-1 lytic activity outside of the context of a host cell. We found that tyloxapol inhibits the hemolytic activity of M. marinum in a concentration dependent manner. The addition of 100-fold less tyloxapol than commonly used for mycobacterial growth differentially inhibits the production and secretion of ESX-1 substrates required for lytic activity. Our findings directly impact how the field interprets data from studies where M. marinum, and potentially other mycobacterial species were grown in tyloxapol. Our findings may explain the original ob-servations linking tyloxapol to anti-tuberculosis activity. Author SummaryTuberculosis, which is caused by Mycobacterium tuberculosis, is one of the worlds deadliest diseases. We lack a clear understanding of how M. tuberculosis and related mycobacterial species cause disease. In the 1950s, it was reported that treating M. tuberculosis infected animals with tyloxapol improved the survival and in some cases protected the animals from death. Tyloxapol is a detergent that is commonly added to mycobacterial cultures to promote dispersed growth in the laboratory. Later studies suggested that tyloxapol altered the interaction between M. tuberculosis and the phagosomal membrane during macrophage infection. The ability to escape the phagosome is essential for mycobacteria to cause disease, and is mediated by a Type VII protein secretion system, ESX-1. Using M. marinum, a well-established model for understanding the molecular mechanisms of ESX-1 secretion, we show that tyloxapol used at more than 100-fold less than what is commonly used to grow mycobacteria in the lab, inhibits ESX-1 secretion. Our findings have widespread implications on how we interpret our findings as a field, and may explain why tyloxapol impacted M. tuberculosis infection of both animals and macrophages. Our study also indicates that tyloxapol can be used as a tool to understand the molecular mechanisms of ESX-1 protein secretion.

Background: With the emergence of drug-resistant strains and an unprecedented threat to control initiatives, tuberculosis remains to be a major public health risk in Ethiopia. Resistance to rifampicin (RR) is an important indicator, since RR is an acceptable surrogate for multidrug-resistant TB (MDR-TB). Over 95% of RR is based on mutations in an 81base pair segment of the rpoB gene, detected using rapid molecular assays. Despite this, detailed molecular epidemiological information is scarce. This study characterized the specific rpoB gene mutation patterns among patients in Addis Ababa, Ethiopia. Methods: A cross-sectional study was conducted in 753 Mycobacterium tuberculosis complex (MTBC) clinical samples, corroborated as positive for MTBC from 2020 to 2024; respective probe mutation patterns were generated by the Xpert MTB/RIF platform. Demographic and clinical variables were also assessed for detecting the potential risk factors. Results: The overall RR-TB rate was 2.3% (17/753). Molecular analysis showed a distinct pattern of mutation, with codon 526 mutations being the most frequent, occurring in 54.3% of the resistance mechanisms. This was followed by those at codons 531 (21.7%) and 533 (15.2%). Most significant was the fact that 100% of RR-TB was observed among treatment-naive patients, providing unequivocal evidence that primary transmission is the exclusive cause of resistance in this population. Moreover, there were no statistically significant correlations between RR-TB and demographic factors, including sex, age, or HIV co-infection. Conclusion: The study demonstrates a steady, low-grade epidemic of RR-TB in Addis Ababa, dominated by a virulent bacterial strain with a distinctive mutation at codon 526. These observations highlight the imperative necessity for a strategic shift from a reactive, clinically-oriented model to proactive public health measures. To effectively break the chains of transmission, we recommend the universal application of drug susceptibility testing, enhanced and socially-directed contact tracing, and integrating molecular surveillance into the TB control program.

Mycobacterium tuberculosis (Mtb) primarily infects human lung macrophages, which serve as its major replication niche. Mtb can manipulate host macrophage cell death pathways to its advantage by inhibiting apoptosis and inducing necrotic cell death. However, the specific necrotic cell death pathway activated in human macrophages after Mtb infection remains unclear. Here, we used the THP-1 cell line and primary human monocyte-derived macrophage (hMDM) to analyze multiple programmed cell death pathways during days 1-3 after Mtb infection. Confocal microscopic analysis demonstrates that Mtb-infected THP-1 cells or hMDMs rarely exhibited apoptosis. Immunoblotting shows that Mtb induces significant CASP3 and GSDME activation in THP-1 cells, but not in hMDMs. We show that Mtb, in THP-1 cells but not hMDM, induces a significant increase in GSDMD cleavage, a hallmark of pyroptosis. MLKL phosphorylation was not observed in THP-1 cells or hMDMs during Mtb infections, indicating an absence of necroptosis. No changes in ferroptosis markers such as GPX4 expression or lipid peroxidation levels were detected. Time-lapse live-cell imaging revealed no lysosomal membrane permeabilization prior to plasma membrane rupture (PMR). However, we observed DNA release from Mtb-infected THP-1 cells and hMDMs after PMR. The DNA released from THP-1 cells exhibits low levels of myeloperoxidase and histone H3 citrullination. High-resolution confocal imaging shows that Mtb is associated with the released DNA. We demonstrate that pyroptosis induction in THP-1 cells is dispensable for the DNA release and cell death induction. In conclusion, our results reveal that Mtb-triggered cell death in hMDMs bypasses canonical cell death pathways like apoptosis, pyroptosis, necroptosis, and ferroptosis. Instead, cell death in both THP-1 cells and hMDMs correlates with DNA release, potentially through a pathway similar to NETosis in neutrophils.

Mycobacterium abscessus is a rapidly growing non-tuberculous mycobacterium with rising global incidence. This pathogen exhibits intrinsic resistance to most antibiotics, presenting a major public health threat. Ethionamide (ETH) requires bioactivation by monooxygenase EthA to form the active ETH-NAD adduct. We previously identified MAB_3513 (NudC) as a phosphohydrolase that confers intrinsic resistance to M. abscessus by hydrolyzing this adduct. However, deletion of nudC results in only partial susceptibility to ETH, indicating the existence of additional resistance mechanisms. This study identified MAB_0984 as the EthR regulator in M. abscessus. Deletion of ethR in a nudC knockout background ({Delta}{Delta}ethR) significantly enhanced ETH-NAD adduct accumulation, leading to hypersusceptibility to ETH. Notably, the {Delta}ethR mutant exhibited higher susceptibility than {Delta}nudC, demonstrating that EthR is a more dominant mediator of ETH resistance than NudC. Furthermore, MAB_0985 (EthA1) and MAB_0103 (EthA2) were identified as the primary EthAs in M. abscessus. Deletion of either gene alone or in combination in the {Delta}nudC reduced adduct formation and increased resistance, while the triple mutant {Delta}{Delta}ethA1{Delta}ethA2 restored wild-type resistance. Using an intergenic region-eGFP reporter system and quantitative reverse transcription-PCR, we demonstrated that EthR confers resistance by specifically suppressing ethA1 expression in M. abscessus. The Mycobacterium tuberculosis EthR inhibitor BDM31343 could boost the efficacy of ETH against M. abscessus by inhibiting EthR. Collectively, this study identified the ethR and ethA genes in M. abscessus for the first time and elucidated their role in mediating resistance to ETH. Therefore, EthR is a promising target for potentiating the efficacy of ETH against M. abscessus. Impact statementMycobacterium abscessus constitutes an escalating global health threat, primarily due to its intrinsic resistance to most antibiotics. This study identifies MAB_0984 (EthR) as a dominant resistance determinant that exerts a more profound impact on ETH susceptibility than the previously characterized NudC. We demonstrate that EthR mediates resistance by specifically repressing the expression of EthA1 (MAB_0985), one of the primary monooxygenases responsible for ETH bioactivation. The EthRMtb inhibitor BDM31343 potentiated the activity of ETH against M. abscessus through inhibition of the EthR. These findings elucidated the mechanism of ETH resistance in M. abscessus, identifying EthR as a promising target for boosting the efficacy of ETH against M. abscessus.

Whole-genome sequencing (WGS) of Mycobacterium tuberculosis (Mtb) is widely used in the epidemiological investigation of recent transmission events, resulting in high-resolution strain typing. Accurate and rapid strain typing is essential for informing outbreak investigations and guiding tuberculosis control strategies. However, the gold-standard reference-guided SNP-calling pipeline currently used for strain typing relies on computationally intensive reference-mapping approaches, making it challenging to perform in many high-burden, resource-limited settings, where simplified and scalable genomic tools are urgently needed. To address these limitations, we explored reference-free methods for medium resolution epidemiology, namely Mtb strain (lineage) typing, using a dataset of 535 complete genomes spanning the human- and animal-adapted lineages. Illumina paired-end reads were simulated from each complete genome, assembled, and analysed using three reference-free, k-mer-based tools: MASH, PopPUNK, and SKA2 (Split K-mer Analysis). Genetic distances were generated for each method and compared with a ground truth lineage assignment from with TB Profiler. Our results demonstrated that reference-free methods can effectively distinguish Mtb lineages, with SKA2 showing the most promising performance across all datasets. SKA2 consistently recovered lineage and sub-lineage structure with high accuracy, demonstrating strong potential as an alternative to traditional WGS workflows. These findings highlight the utility of reference-free methods, particularly SKA2, for enabling accessible, scalable, and rapid Mtb strain typing, while supporting genomic epidemiology with low computational resources.

Ziehl-Neelsen (ZN) smear microscopy remains central to tuberculosis (TB) diagnosis and treatment monitoring, yet its sensitivity is limited by incomplete recovery of Mycobacterium tuberculosis during pre-analytical processing. This study evaluated whether modifying centrifugation force and duration improves bacillary recovery and ZN smear performance. Laboratory experiments were conducted using M. tuberculosis H37Rv and pulmonary TB sputum samples. Following NALC-NaOH decontamination, samples were centrifuged at 2,000, 3,000, or 6,000 x g for 40 min, and the effect of centrifugation time at 3,000 x g was assessed by comparing 20 and 40 min using the same specimens. ZN smear grading and positivity were evaluated in triplicate and compared statistically, with significance set at P < 0.05. In H37Rv suspensions, smear grading increased with higher centrifugal force, while smear positivity plateaued at 3,000 x g. In contrast, clinical sputum samples showed progressive increases in both smear grading and positivity with increasing centrifugal force, with statistically significant improvements in positivity (p = 0.0097). Extending centrifugation time at 3,000 x g did not change smear positivity in laboratory suspensions or clinical sputum (P = 0.30). These findings indicate that standard centrifugation conditions are sufficient for laboratory strains, whereas higher centrifugal forces enhance bacillary recovery from clinical sputum, improving ZN smear sensitivity. Optimizing relative centrifugal force during pre-analytical processing may therefore reduce false-negative results and strengthen the diagnostic and treatment-monitoring performance of ZN smear microscopy in routine TB laboratories.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb), remains a major global health challenge, with approximately 10.8 million new cases and 1.25 million deaths reported in 2023. Human responses to M.tb are heterogeneous with clinical outcomes including bacterial clearance, asymptomatic latent M.tb infection, and severe fatal pulmonary TB. Here, we aim to address knowledge gaps in the organization of M.tb granulomas by identifying cell-based spatial features indicating asymptomatic lung infection. To address this gap, which cannot be directly studied in humans, we used lung sections from M.tb infected Diversity Outbred mice with acute pulmonary TB, asymptomatic M.tb infection, or chronic pulmonary TB that were stained for T cells, B cells, macrophages, and bronchiolar epithelial cells by multiplexed immunofluorescence. We first developed a new, accurate model to automatically segment lung granulomas, detect/quantify the cell types within granulomas, and extract the location of immune cells in granulomas for each disease state. Analysis of model-derived results show that lung granulomas from asymptomatic mice have a characteristic spatial profile consisting of higher CD4+ and CD8a+ T cell densities, closer B cell proximity to bronchiolar epithelium, and increased T cell-macrophage proximity in asymptomatic M.tb infection. Next, we propose a second novel approach to utilize a large language model (LLM) to independently decode complex cellular patterns within granulomas, and distinguished key immunological signatures: balanced immune expression in asymptomatic M.tb mice, dysfunctional responses with low cellularity in acute TB, and highest immune cells in chronic TB. Overall, the results from this study show that lung granulomas in asymptomatic infection are characterized by increased T cell density, increased numbers of peribronchiolar B cells, and T cells closer to macrophages as compared to acute and chronic TB. These methods and results help establish an automated pipeline to extract and analyze data from multiplexed fluorescence images and provide a foundation to better understand how granuloma architecture varies by disease state.

The lack of a reliable chronic murine model limits drugs evaluation against Mycobacterium abscessus. Models show discrepancies, especially regarding host factors (mouse strain, sex and age). Using beads-model, we compared BALB/cJRJ and C57BL/6NCrl across sexes and ages. BALB/cJRJ showed more sustained infection and lower variability, with no significant sex- or age-related differences. Considering these results and the higher prevalence of NTM pulmonary infections in female patients, 5-6 weeks-old female BALB/cJRJ are appropriate for M. abscessus beads-model.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), has regained its position as the worlds leading killer among infectious diseases. Despite extensive research progress across epidemiology, diagnosis, drug development, treatment regimens, vaccines, drug resistance, virulence factors, and immune mechanisms, MTB-related knowledge remains fragmented across thousands of publications, limiting its effective use. To address this gap, we present MTB-KB, a literature-curated knowledgebase that systematically integrates high-impact findings from eight major sections of TB research. The current release contains 75,170 associations from 1,246 publications, covering 18,439 entities standardized using authoritative databases and WHO-endorsed classifications. A central feature is the interactive knowledge graph, which links cross-section associations to reveal and infer MTB-host interactions, treatment strategies, and vaccine development opportunities. MTB-KB also provides a user-friendly interface with browsing, advanced search, and statistical visualization. Overall, by consolidating dispersed MTB knowledge into a structured and accessible platform, MTB-KB provides a valuable resource for researchers, clinicians, and policymakers, supporting both basic and clinical TB research, enabling evidence-based TB prevention, diagnosis, and treatment, and contributing to global elimination efforts. MTB-KB is accessible at https://ngdc.cncb.ac.cn/mtbkb/.

Rationale: Sputum-based testing using Xpert MTB/RIF Ultra (Xpert) is the most common molecular testing method for diagnosing tuberculosis (TB). Objectives: To evaluate whether sputum quality influences Xpert positivity and diagnostic accuracy. Methods: We screened consecutive people for presumptive TB in India, the Philippines, Vietnam, Nigeria, South Africa, Uganda, and Zambia as part of the R2D2 TB Network and ADAPT studies. Participants provided 2-3 sputum samples for Xpert and culture reference testing. The quality of the first sputum sample was graded following standardized procedures by trained research staff and used for Xpert testing. We performed logistic regression to evaluate whether sputum grade was independently associated with Xpert positivity, and calculated sensitivity and specificity of Xpert against a culture-based microbiological reference standard (MRS). Measurements and Main Results: Among 1,855 participants, 798 (43%) were female, 348 (19%) were living with HIV (PLHIV), and 1795 (97%) had a cough of [&ge;]2 weeks. Overall, 313 (17%) had a positive Xpert result. Most sputum samples were salivary (83%). Xpert positivity was lowest among salivary samples (16.1%) and highest among purulent samples (31.2%). After adjusting for demographic and clinical variables, there was no significant association between any sputum grade and Xpert positivity. Xpert sensitivity (salivary: 89%, mucoid: 91%, mucopurulent: 87%, purulent: 100%) and specificity (>98%) were high across sputum grades. Conclusions: Sputum quality was not independently associated with Xpert positivity and Xpert sensitivity was high across all sputum grades. These findings support molecular testing of all sputum samples for TB diagnosis regardless of macroscopic appearance.

BackgroundMoxifloxacin is a key component of current MDR-TB therapy regimens. The choice to include it in therapy at standard or higher doses is based on the lack or presence of resistance mutations conferring low-level or high-level resistance to moxifloxacin, as detected by the Line probe assay (LPA). Due to inherent phenotypic and genotypic discordance, such resistance must be reconfirmed phenotypically using liquid culture and drug susceptibility testing (LC-DST) at critical concentration and clinical breakpoint of the drug. This takes several weeks, delaying the therapeutic decision. The current study intends to shorten this time by performing phenotypic DST directly on sputum samples. MethodsA cross-sectional study was conducted for 18 months from October 2023 to April 2025, in which smear positive sputum samples that were resistant to Rifampicin or Isoniazid or both were subjected to Direct Moxifloxacin DST, irrespective of patient characteristics. Results obtained by Direct DST were compared against Indirect LC-DST as the gold standard as well as with LPA to evaluate the diagnostic accuracy and time savings with direct DST. ResultsDirect DST exhibited high accuracy of 98.18%, high sensitivity (90.91%), high specificity (98.99%), excellent concordance (98.18%) and almost perfect agreement (kappa value - 0.901) when compared to Indirect DST. It saved an average of 10 {+/-} 3.20 days over Indirect DST to obtain the valid results. Similar performance was also observed in comparison to LPA with good sensitivity (90.91%), specificity (98.99%) and accuracy (98.18%). Significant discordance was however noted in classification of resistance by both direct and indirect DST compared to LPA. Few error rates and minimal cost advantages were some of the disadvantages of Direct-DST. ConclusionDirect DST demonstrated excellent performance characteristics, making it a reliable and rapid alternative to the gold standard, saving significant time in guiding therapeutic decisions for effective patient management.

Background: Host genetics alone explains limited susceptibility to tuberculosis (TB), particularly in people with HIV (PWH). Protein quantitative trait loci (pQTLs), genetic variants that regulate plasma protein levels, may bridge genetic and immunological mechanisms underlying TB progression. Methods: We conducted cis-pQTL mapping in 60 PWH who progressed to active TB and 194 matched controls from the Swiss HIV Cohort Study. Plasma proteomes were quantified via high-resolution mass spectrometry (dia-PASEF), and genotype-protein associations were analyzed separately in TB and control groups. Results: TB progressors harbored 26 cis-pQTLs linked to 12 proteins uniquely enriched in immune pathways (antigen presentation, complement activation, phagocytosis, and T-cell regulation). Controls showed 107 cis-pQTLs linked to 14 targets. Gene Ontology enrichment revealed 46 immune biological processes in TB versus only 1 in controls, with HLA-C, C4B, and CHIT1 as key TB-specific proteins. Conclusions: Integrating proteomics with genomics suggests differential regulation of immune proteins associated with TB progression in PWH. hese genetically anchored protein candidates support follow-up studies and future biomarker evaluation for TB risk prediction.

BackgroundReliable detection of latent Mycobacterium tuberculosis (Mtb) infection (LTBI) remains challenging, particularly in TB contacts and immunocompromised individuals, where interferon-{gamma} release assays (IGRAs) demonstrate variable sensitivity. IP-10, a chemokine produced at substantially higher concentrations than IFN-{gamma}, represents a promising immune marker. This study aimed to evaluate the diagnostic performance of two IP-10 based assays RIDA(R)QUICK TB (lateral flow) and RIDASCREEN(R) TB (ELISA), by comparison with QuantiFERON-TB Gold Plus (QFT-Plus) assay or a composite reference standard. MethodsA cross-sectional diagnostic accuracy study enrolled 99 adults: 49 with culture-confirmed active pulmonary TB, 30 close TB contacts and 20 individuals with autoimmune disease, in Bucharest, Romania. All participants underwent RIDA Quick, RIDA Screen and QFT-Plus testing. Indeterminate results for all assays were reclassified using a composite reference standard. ResultsAgainst culture in active TB cases, RIDA(R)QUICK TB demonstrated a sensitivity of 85.7% (95% CI: 72.8-94.1) and PPV of 97.7%, while RIDA(R)SCREEN TB achieved 91.8% sensitivity (95% CI: 80.4-97.7) and 97.8% PPV. Specificity and NPV could not be reliably estimated due to the near-absence of true-negative individuals. Agreement with QFT-Plus was moderate to good ({kappa}=0.47-0.93).ROC analysis performed against QFT-Plus as a comparator demonstrated good immunological discrimination for RIDA(R)QUICK TB (AUC = 0.828) and RIDA(R)SCREEN TB (AUC = 0.767), reflecting concordance with QFT-Plus rather than diagnostic accuracy against confirmed infection. ConclusionIP-10 based assays demonstrated higher sensitivity than QFT-Plus and excellent PPV across bacteriological standard, supporting their use as complementary tools for LTBI detection. Larger, more heterogeneous cohorts are needed to accurately define specificity and operational integration.