Search Results (318)

The Mycobacterium tuberculosis complex (MTBC) represents one of the most significant bacterial pathogen groups affecting both animals and humans worldwide. This review provides a comprehensive analysis of MTBC species distribution across different animal hosts and evaluates current laboratory diagnostic methodologies for pathogen detection and identification. The complex comprises seven primary species: Mycobacterium bovis, M. caprae, M. tuberculosis, M. microti, M. canettii, M. africanum, and M. pinnipedii, each exhibiting distinct host preferences, geographical distributions, and pathogenic characteristics. Despite sharing >99% genetic homology, these species demonstrate variable biochemical properties, morphological features, and pathogenicity profiles across mammalian species. Current diagnostic approaches encompass both traditional culture-based methods and advanced molecular techniques, including whole genome sequencing. This review emphasises the critical importance of rapid, accurate detection methods for effective tuberculosis surveillance and control programmes in veterinary and public health contexts. Full article

Background/Objectives: The diagnosis of Mycobacterium tuberculosis complex (MTBC) and nontuberculous mycobacterial (NTM) infections is accomplished by three main diagnostics methods: smear microscopy, culture, and molecular testing. Diagnostic algorithms used by laboratories can significantly impact clinical and infection control management. Current Canadian Tuberculosis Standards recommend the use of nucleic acid amplification testing (NAAT) for smear-positive patients and smear-negative patients upon request. An alternative algorithm is to utilize NAAT in the Panel approach on all samples, pulmonary and extrapulmonary, to potentially reduce time to diagnosis and treatment. This alternative approach was implemented in November 2019 at the Newfoundland and Labrador Public Health and Microbiology Laboratory (NL PHML) using a laboratory-developed multiplex real-time PCR (LDT m-qPCR) assay targeting Mycobacterium spp. (Myco spp.) and MTBC, performed in parallel with smear and culture. Methods: To investigate the impact of this alternate testing approach, we conducted an observational retrospective analysis of laboratory diagnostic and treatment data, recognizing that temporal changes in epidemiology, clinical practice, and laboratory workflow may also have influenced outcomes. To complete this, study data from three years before and four years after implementation were gathered. Results: The sensitivity/specificity of the smear, m-LDT qPCR-MTBC, m-LDT qPCR-Myco spp., and culture assays in this study were 18.1%/100%, 96.7%/99.8%, 47.6%/99.0%, and 96.8%/100%, respectively. The gold standard utilized for these calculations was clinical diagnosis for active MTBC disease and culture for NTM infections, recognizing that the use of clinical diagnosis may introduce subjectivity. The Panel approach reduced the time to diagnosis of tuberculosis MTBC by 29 days (p < 0.0001) for NL PHML, and when modelled for a laboratory with rapid culture identification, diagnosis was reduced by 14 days (p = 0.003). Among non-empirically treated tuberculosis patients, the time to treatment was decreased by 25.5 days (p < 0.001). For NTM infections, rapid diagnostics only affected one patient’s treatment. This finding agrees with clinical management guidelines, which do not routinely utilize rapid diagnostics for the diagnosis of disease or treatment decisions. The cost implications of additional NAAT testing were calculated to be an increase of CAD 23.62 per sample. Conclusions: Our findings support the adoption of a molecular assay for MTBC as an initial diagnostic tool to decrease time to diagnosis and time to treatment, depending on local epidemiology and irrespective of smear status. Utilizing a molecular assay for genus level identification of NTM had minimal impact on clinical management suggesting its limited diagnostic utility in a broad population setting. Full article

Cell division is critical for the survival, growth, pathogenesis, and antibiotic susceptibility of Mycobacterium tuberculosis (Mtb). However, the regulatory networks governing the transcription of genes involved in cell growth and division in Mtb remain poorly understood. This study aimed to investigate the impact of BlaI overexpression on cell division and growth in Mtb and elucidate the underlying mechanisms. Mycobacterium smegmatis mc²155 was used as the model organism. Recombinant strains overexpressing BlaI were constructed. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), ethidium bromide and Nile red uptake assays, minimum inhibitory concentration (MIC) determination, drug resistance analysis, quantitative real-time PCR (qRT-PCR) assays, and electrophoretic mobility shift assay (EMSA) were employed to assess changes in bacterial morphology, cell wall permeability, antibiotic susceptibility, gene transcription levels, and the interaction between BlaI and its target genes. Overexpression of BlaI disrupted bacterial division in M. smegmatis, leading to growth delay, cell elongation, and formation of multi-septa. It also altered the lipid permeability of the cell wall and enhanced the sensitivity of M. smegmatis to β-lactam antibiotics. BlaI overexpression affected the transcription of cell division-related genes, particularly downregulating ftsQ. Additionally, BlaI negatively regulated the transcription of Rv1303—a gene co-transcribed with ATP synthase-encoding genes—inhibiting ATP synthesis. This impaired the phosphorylation of division complex proteins, ultimately affecting cell division and cell wall synthesis. Overexpression of BlaI in Mtb interferes with bacterial division, slows growth, and alters gene expression. Our findings identify a novel role for BlaI in regulating mycobacterial cell division and β-lactam susceptibility, providing a foundation for future mechanistic studies in M. tuberculosis, with validation required to assess relevance to clinical tuberculosis—though validation in M. tuberculosis and preclinical models is required. Full article

Tuberculosis (TB), primarily caused by Mycobacterium tuberculosis (Mtb), remains a leading cause of infectious disease mortality worldwide. Global TB control efforts face several hurdles, including the lack of a broadly effective vaccine, limited sensitivity of current diagnostics, particularly for paucibacillary and extrapulmonary TB, and significant adverse effects associated with prolonged small-molecule drug regimens. The growing prevalence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains further underscores the urgent need for innovative therapeutic strategies. We outline characteristics of next-generation TB therapeutics. We show that antibody (Ab)-drug conjugates (ADCs) satisfy many of those desirable characteristics. Since a major hurdle to this approach lies in Mtb-specific Abs, we highlight an open-access resource comprising a broad panel of Mtb-specific mouse monoclonal antibodies targeting key factors involved in Mtb survival, immune evasion, and pathogenesis. These critical Mtb virulence factors include heat shock proteins (GroES, DnaK, and HspX), surface-associated or secreted proteins (LAM, Ag85, HBHA, Mpt64/CFP-21, and PhoS1/PstS1), cell wall/envelope-associated proteins (LprG/p27), and detoxifying enzymes (KatG and SodA). The resource provides full-length sequences of the immunoglobulin variable regions, enabling antibody engineering and facilitating translational TB research across vaccine design, diagnostic development, and immunotherapeutic applications, in addition to ADCs. This ADC targeted delivery strategy holds promise for overcoming TB heterogeneity and eliminating both active and dormant Mtb populations within a single therapeutic formulation and offers a novel avenue for precision TB treatment. Full article

It is estimated that one in four people worldwide carries Mycobacterium tuberculosis bacteria. MPT64 is a protein exclusively secreted by Mycobacterium tuberculosis complex (MTC) bacteria. It serves as a crucial diagnostic marker and plays a role in the bacterium’s survival by modulating the host immune response. Consequently, the development of innovative diagnostic tools based on MPT64, as well as the production of high-purity MPT64 protein to support research on tuberculosis pathogenesis and the advancement of novel therapeutic strategies, is of great importance. In this study, optimization experiments were conducted to produce this protein in E. coli with high yield and purity. First, a gBlock was designed by codon optimization and then cloned into a plasmid vector using the LIC method. For more efficient production, E. coli BL21(DE3)-R3-pRARE2 strain, which carries rare tRNAs for rare codons, was used as the host. Five different culture media were tested to maximize protein production, with the highest yield obtained in eBHI medium. The resulting protein yield was 4.9 mg/L. To the best of our knowledge, this study provides the most detailed information on the recombinant production and characterization of MPT64 to date. Therefore, these results contribute important data for future studies on the MPT64 protein. Full article

The early secreted antigenic target of 6 kDa (ESAT-6), a main effector molecule of the ESX-1 secretion system, is identified as a virulence determinant and immunoregulatory protein of Mycobacterium tuberculosis (Mtb), affecting the interaction between host immune cells and pathogens. ESAT-6 facilitates the survival of mycobacteria and their cell-to-cell spreading through membrane-permeabilizing activity and the regulation of host immune cell functions. In this review, we first summarize the recent knowledge of the roles of ESAT-6 in the survival of bacteria, phagosomal escape, and pathogenicity during Mtb infection. Then, we focused on its complex immunomodulatory effects on different immune cells, such as macrophages, dendritic cells, neutrophils, and T cells, accentuating its capability to either facilitate or inhibit immune responses through different signaling pathways. While our review has summarized its main roles in immunopathology in the context of tuberculosis, we additionally search for emerging evidence indicating that ESAT-6 has anti-inflammatory and immunosuppressive properties. Particularly, we discuss recent preclinical studies showing its capability to suppress transplant rejection and alloimmunity, probably via the induction of regulatory T cells. Nevertheless, the potential clinical use of ESAT-6 remains uncertain and needs further verification by comprehensive preclinical and clinical studies. Thus, we propose that ESAT-6 may be exploited to ameliorate immunopathology in TB infection and to suppress immune-mediated inflammation or transplant rejection as well. Full article

Tuberculosis (TB) remains a major global health challenge, particularly in resource-limited settings where access to rapid and reliable diagnostics is limited. Conventional diagnostic methods, such as smear microscopy and culture, are either time-consuming or lack adequate sensitivity. This study optimized recombinase polymerase amplification (RPA) using 16 primer combinations targeting IS6110 highly specific to the Mycobacterium tuberculosis complex (MTC). A novel naked-eye assay, TB-GoldDx, was developed by integrating RPA combined with gold nanoparticles (AuNPs), enabling equipment-free diagnostics. TB-GoldDx demonstrated a detection limit of 0.001 ng of MTB H37Rv DNA (~210 bacilli) per 25 µL reaction. Among 100 bacterial strains, it achieved 95.83% sensitivity and 100% specificity among 100 bacterial strains, comprising 72 MTB isolates and 28 nontuberculous bacterial species. In 140 sputum samples, the assay showed 81.43% sensitivity and 58.57% specificity versus acid-fast bacilli (AFB) smear microscopy, with sensitivity improving to 95.45% in high-load AFB 3+ specimens. Compared to a commercial line probe assay (LPA), TB-GoldDx exhibited slightly higher sensitivity (84.78% vs. 82.61%) but lower specificity (54.05% vs. 78.38%). Delivering rapid, visual results in under an hour, TB-GoldDx offers a low-cost, easily deployable solution for point-of-care tuberculosis detection, especially in underserved regions, reinforcing global End TB efforts. Full article

Tuberculosis (TB) is an infection caused by Mycobacterium tuberculosis complex (MTBC), which can be exacerbated by fungal infections. This study evaluated the clinical characteristics and virulence of Candida spp. in patients with tuberculosis. Antifungal sensitivity, phospholipase and proteinase production, biofilm formation, phagocytic index, and reactive oxygen (ROS) and nitrogen (RNS) species were assessed. Candida spp. were isolated from 14 patients, 28.5% women and 71.4% men, mainly from sputum and tracheal secretions. Five (35.7%) patients were co-infected with Mycobacterium, Candida, and HIV. Candida albicans (78.6%) and Candida tropicalis (21.4%) were identified in all 14 patients. All isolates showed sensitivity to amphotericin B and dose-dependent responses to fluconazole (16 μg/mL). Phospholipase activity was detected in 35.7% of the isolates, whereas all isolates showed proteinase activity (100%). A significant difference in phospholipase activity, phagocytosis, and production of reactive oxygen species (ROS) and nitrogen species (RNS) was observed when Candida isolates from patients with TB, living with or without HIV, were compared to Candida isolates from healthy individuals. All isolates were biofilm producers. This study highlights the relevance of mycoses diagnosis in patients with TB, since Candida spp. may be more virulent and contribute to the deterioration of the clinical condition. Full article

Tuberculosis (TB) remains a formidable global public health challenge. The rising prevalence of drug-resistant TB and increased human immunodeficiency virus(HIV) co-infection further exacerbate TB control efforts. Mycobacterium tuberculosis (Mtb) achieves highly heterogeneous infection outcomes (active disease, latency, or clearance) through immune evasion and host metabolic reprogramming. While conventional diagnostic techniques offer cost-effectiveness and accessibility without complex infrastructure, they are constrained by low sensitivity, prolonged turnaround times, and an inability to distinguish latent TB infection (LTBI) from active TB disease (ATB). Recent research into host-derived biomarkers provides a promising strategy to overcome diagnostic bottlenecks by deciphering characteristic molecular changes in host–pathogen interactions. This review systematically reviews advances in host-derived biomarkers for TB diagnosis, critically discussing the clinical potential, translational challenges, and future research directions of integrated multi-omics biomarker panels to enhance diagnostic sensitivity and specificity, differentiate ATB from LTBI, and guide precision therapy. Full article

Mycobacterium (M.) tuberculosis mostly spreads from active tuberculosis (TB) patients to human contacts, although human-to-animal and animal-to-human transmission has been described. Here, we present a rare case of rifampicin-resistant tuberculosis (RR-TB) transmission from a companion dog to its owner, highlighting the zoonotic potential of the pathogen. Namely, a 37-year-old Croatian man was diagnosed with RR-TB, with whole-genome sequencing analysis revealing a close genetic link to the strain isolated from his dog, which had died of miliary TB six years earlier. This case emphasizes the complexity of TB transmission dynamics, particularly involving companion animals, and underlines the importance of integrated “One Health” approaches for TB control. Awareness of zoonotic TB risks is essential for the early detection and prevention of cross-species transmission, especially in vulnerable populations and households with close human–animal contact. Full article

Evolving technologies available to clinical laboratories and laboratory-related updates to clinical guidelines both drive the need for clinical laboratories to keep their test menu updated and in line with current technological and clinical developments. Our laboratory has developed a targeted Illumina-based amplicon next-generation sequencing (NGS) assay to interrogate the hsp65 and erm(41) genes of Mycobacterium spp. for the purposes of providing species-level ± subspecies-level identification of Mycobacterium spp. organisms in clinical samples and genotypic predictions for inducible macrolide resistance (in the case of M. abscessus complex members). The developed assay demonstrated 100% sensitivity and specificity for M. tuberculosis and M. abscessus complex cultured organisms, 98% ID overall concordance relative to the available reference identification, and a nearly 60% “rescue” rate for primary samples that could not be identified using our previous method. There was 94.6% concordance between genotypic and phenotypic results for inducible macrolide resistance. The developed assay was successfully implemented in our clinical laboratory and has been accredited for clinical use. Full article

Bacterial natural ecological niches are characterized by variations in the availability of nutrients, resulting in a complex metabolism. Their impressive ability to adapt to changeable nutrient conditions is possible through the utilization of large amounts of substrates. Recent discoveries in bacterial metabolism have suggested the importance of polyamine metabolism in bacteria, particularly in those of the order Actinomycetales, in enabling them to survive in their natural habitats. This makes such enzymes promising targets to inhibit their growth. Since the polyamine metabolisms of soil bacteria of the genus Streptomyces and the human pathogenic Mycobacteria are surprisingly similar, target-based drug development in Streptomyces and Mycobacterium spp. is an alternative approach to the classical search for antibiotics. The recent development of drugs to treat epidemic diseases like tuberculosis (TB) has gained attention due to the occurrence of multidrug-resistant strains. In addition, drug repurposing plays a crucial role in the treatment of various complex diseases, such as malaria. With that notion, the treatment of TB could also benefit from this approach. For example, molecular chaperones, proteins that help other proteins to fold properly, are found in almost all living organisms, including the causative agents of TB. Therefore, targeting these molecules could help in the treatment of TB. We aim to summarize our knowledge of the nitrogen and carbon metabolism of the two closely related actinobacterial genera, Streptomyces and Mycobacterium, and of the identification of new potential drug targets. Full article

Tuberculosis (TB), primarily caused by Mycobacterium tuberculosis complex (MTBC), remains a global health challenge and can lead to severe pulmonary and extrapulmonary complications. Multidrug-resistant TB (MDR-TB) poses additional challenges, requiring advanced diagnostic and treatment strategies. This study evaluates the BD MAX MDR-TB molecular test for a rapid diagnosis of MDR-TB, detecting resistance to rifampicin (RIF) and isoniazid (INH). The BD MAX MDR-TB test, utilizing real-time PCR, was used to analyze specimens collected from TB-suspected patients, identifying MTB DNA and mutations associated with rifampicin and isoniazid resistance. Results were compared with traditional drug susceptibility testing, and 79 out of 638 samples tested were positive for MTB DNA, with 65 showing a sufficient amount of genetic material for resistance gene identification. The BD MAX test showed a 100% correlation with phenotypic rifampicin resistance, though discrepancies were noted for isoniazid resistance, with a 93% concordance. The BD MAX MDR-TB test is an effective tool for a rapid diagnosis of MDR-TB, especially for rifampicin resistance. However, it may not detect certain mutations related to isoniazid resistance. Complementary tests like Xpert MTB/XDR or whole-genome sequencing could improve diagnostic accuracy and support more effective TB control strategies. Full article

Worldwide, several million people are infected with mycobacteria such as Mycobacterium tuberculosis (M. tb) or non-tuberculous mycobacteria (NTM). In 2023, 10.8 million cases and 1.25 million deaths due to M. tb were recorded. In Europe and North America, the emergence of NTM is tending to outstrip that of M. tb. Among pulmonary NTM, Mycobacterium avium complex (MAC) is the most common, accounting for 80% of NTM infections. First-line treatment requires the combination of at least three antibiotics over a long period and with different mechanisms of action to limit cross-resistance. The challenge is to discover more effective new anti-MAC molecules to reduce the duration of treatment and to overcome resistant strains. The aim of this review is to present an overview of the challenges posed by MAC infection such as side effects, reinfections and resistance mechanisms. The latest therapeutic options such as the optimized combination therapy, drug repurposing and the development of new formulations, as well as new anti-MAC compounds currently in (pre)clinical trials will also be discussed. Full article

Background and Objectives: Tuberculosis (TB) is one of the most common infectious diseases in developing countries. The resistance of the causative agent, Mycobacterium tuberculosis, to two or more first-line anti-TB drugs results in multidrug-resistant (MDR) TB, posing a serious challenge to the control of TB worldwide. This study was designed to determine the changes in drug resistance over time in TB strains isolated from patients in all departments of Uludağ University Hospital in western Türkiye. Materials and Methods: We retrospectively analyzed 104,598 clinical samples sent to our laboratory for the investigation of the presence of TB between 1996 and 2023. BACTEC 460 TB, BACTEC MGIT 960 culture systems and Löwenstein–Jensen medium were used for the culture of these samples. The susceptibility of M. tuberculosis complex strains grown in culture to isoniazid (INH) (0.1 μg/mL), rifampicin (RIF) (1.0 μg/mL), ethambutol (ETB) (5.0 μg/mL) and streptomycin (SM) (1.0 μg/mL) antibiotics was studied according to the manufacturer’s recommendation. Results: Out of 104,598 patient samples, 2752 (2.6%) were culture-positive, and the susceptibility test results of 1869 of these were analyzed. Of the isolates, 358 (19.2%) were found to be resistant to at least one first-line drug, i.e., INH, RIF, ETB, or SM. In addition, 2.9% were resistant to two or more first-line drugs. Conclusions: Drug susceptibility testing is essential to ensure the optimal treatment and control of drug-resistant TB strains. This study highlights the value of ongoing efforts to control tuberculosis drug resistance in the fight against this disease. Full article