Search Results (150)

Background/Objectives: Mycobacterium avium, a member of Mycobacterium avium complex (MAC), is an emerging opportunistic pathogen causing MAC-pulmonary disease (PD). Fluoroquinolones (FQs), along with ethambutol (EMB) and rifampicin, are recommended for macrolide-resistant MAC-PD; however, FQ-resistant M. avium have been reported worldwide. WQ-3810 is an FQ with high potency against FQ-resistant pathogens; however, its activity against M. avium has not yet been studied. Methods: In this study, we conducted a DNA supercoiling inhibitory assay to evaluate the inhibitory effect of WQ-3810 on recombinant wild-type (WT) and four mutant DNA gyrases of M. avium and compared the IC₅₀s of WQ-3810 with those of ciprofloxacin (CIP), levofloxacin (LVX), and moxifloxacin (MXF). In addition, we examined WQ-3810’s antimicrobial activity against 11 M. avium clinical isolates, including FQ-resistant isolates, with that of other FQs. Furthermore, we assessed the synergistic action of WQ-3810 with the combination of either EMB or isoniazid (INH). Results: In a DNA supercoiling inhibitory assay, WQ-3810 showed 1.8 to 13.7-fold higher efficacy than LVX and CIP. In the MIC assay, WQ-3810 showed 4 to 8-fold, 2 to 16-fold, and 2 to 4-fold higher antimicrobial activity against FQ-resistant isolates than CIP, LVX, and MXF, respectively. The combination of WQ-3810 and INH exhibited a synergistic relationship. Conclusions: The overall characteristics of WQ-3810 demonstrated greater effectiveness than three other FQs, suggesting that it is a promising option for treating FQ-resistant M. avium infections. Full article

Treatment of Mycobacterium tuberculosis requires multi-drug regimens, and resistance to any individual antibiotic can compromise outcomes. For slow-growing organisms like M. tuberculosis, rapid detection of resistance-conferring mutations enables timely initiation of effective therapy. Conversely, confirming wild-type status in resistance-associated genes supports confidence in standard regimens. We developed an amplicon-based next generation sequencing (amplicon tNGS) assay on the Illumina platform targeting eight genes linked to resistance to isoniazid, rifampin, ethambutol, pyrazinamide, and fluoroquinolones. Sequencing results were analyzed using a custom bioinformatics pipeline. Forty-seven samples were used for assay development, and 37 additional samples underwent post-implementation clinical validation. Compared to whole genome sequencing (WGS), amplicon tNGS demonstrated 97.7% sensitivity, 98.9% specificity, and 98.7% overall accuracy for variant detection in targeted regions. Resistance prediction showed 79.3% concordance with WGS; discrepancies were primarily due to mutations outside of target regions. Among post-implementation samples, 27/37 passed quality metrics for all targets, with 95.7% concordance between amplicon tNGS results and final susceptibility results. This assay is now in use in our laboratory and offers significantly faster turnaround than both WGS and phenotypic methods on cultured isolates, enabling more rapid, informed treatment decisions for tuberculosis patients. Full article

Cold Shock Proteins (Csps) are multifunctional regulators critical for bacterial stress adaptation. While Csps are known to regulate biofilm formation and low-temperature growth in some species, their roles in mycobacteria remain unclear. Here, we explored the functions of three Csps (CspA1, CspA2, and CspB) in Mycobacterium smegmatis. We found that CspA1 promotes biofilm formation and isoniazid (INH) resistance but negatively affects oxidative stress resistance. In contrast, CspB promotes biofilm formation, whereas CspA2 appears functionally redundant in this process. Notably, CspB and CspA2 do not contribute redundantly to oxidative stress resistance. Proteomic analysis revealed that CspA1 significantly modulates the expression of key metabolic and stress-response proteins, including WhiB3 and KatG. Our findings establish CspA1 as a key regulatory factor in mycobacteria, linking metabolic adaptation to biofilm-associated drug resistance and oxidative defense. Full article

Objectives: To investigate epidemiological/drug-resistance characteristics and identify potential factors related to drug-resistant and clustered tuberculosis in Sichuan. Methods: A total of 295 Mycobacterium tuberculosis (MTB) isolates were collected from surveillance sites in Sichuan from 2019 to 2021. The minimum inhibitory concentrations (MICs) of 12 anti-TB drugs were acquired using the broth microdilution method, followed by whole-genome sequencing (WGS) analysis. Results: Of 268 MTB isolates with both WGS and drug-susceptibility testing (DST) results, 159 (59.3%, 159/268) strains belonged to the Beijing lineage (L2). Isoniazid had the highest resistance rate (15.3%, 41/268), followed by rifampicin (9.3%, 25/268). The sensitivity of WGS to predict drug resistance varied from 75% to 97.6%, and the specificity was above 96.0% for all. rpoB Ser450Leu (41.7%, 10/24) and katG Ser315Thr (70%, 28/40) were the most frequent mutations in rifampicin and isoniazid resistance isolates, respectively. The clustering rate in Sichuan was 9.3% (25/268), and patients ≤ 24 years old (aOR = 11.697; 95% CI: 0.817–167.463) had a greater risk of clustering. Conclusions: Our findings prove that WGS is a promising tool for predicting drug resistance to isoniazid, rifampicin, ethambutol, moxifloxacin and levofloxacin in Sichuan. The higher resistance rate to isoniazid emphasizes the urgent need for susceptibility testing surveillance and application management. Improving the diagnosis, treatment and management of patients ≤ 24 years old may reduce the transmission of MTB in Sichuan. 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

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

Background: Tuberculosis remains a significant global health issue, and the rise of drug-resistant strains is becoming increasingly concerning. Currently, treatment options are limited to systemic regimens; however, developing topical drug delivery systems could offer advantages for treating cutaneous tuberculosis (CTB) when applied directly to the lesions. We developed topical emulsions using the self-emulsification mechanism that combine fixed doses of isoniazid (INH) and rifampicin (RIF) using a quality-by-design approach. Methods: Preformulation studies pertaining to drug solubility in various solvents, the construction of pseudoternary diagrams to identify self-emulsification regions for each tested excipient combination, and the preparation of checkpoint formulations were conducted and visually examined. Formulations displaying no physical instabilities were subsequently exposed to characterization experiments, including droplet size determination, zeta potential, size distribution, viscosity, pH, self-emulsification, cloud point, robustness to dilution, and thermodynamic stability assessment. Three selected formulations were consequently subjected to membrane release experiments, followed by skin diffusion studies, and INH and RIF stability in these emulsions was determined, because these drugs have a known interaction. Conclusions: While incorporating essential oils in a topical formulation improved RIF solubility, it also resulted in several instabilities. RIF exhibited greater susceptibility to degradation under higher temperatures and lower pH conditions. However, drug release from all formulations tested was confirmed. Notably, olive oil microemulsions demonstrated the most favorable characteristics for dermal drug delivery; nonetheless, drug diffusion into and through the skin (which was not desired) could not be quantified. Despite these challenges, the findings indicate that topical drug delivery systems using the self-emulsification process can facilitate the direct treatment of CTB. Full article

Background: Extrapulmonary tuberculosis (TB) presents significant diagnostic challenges, particularly in the context of multidrug-resistant (MDR) strains. This study assessed the utility of the WHO-recommended rapid molecular assays, originally validated for pulmonary TB, in diagnosing extrapulmonary TB and detecting the MDR Mycobacterium tuberculosis complex (MTBC). Materials and Methods: A total of 6274 clinical samples, including 4891 pulmonary and 1383 extrapulmonary samples, were analyzed between 2019 and 2022 using the BD MAX™ MDR-TB assay (BD MAX), the Xpert^® MTB/RIF assay (Xpert MTB/RIF), the Xpert^® MTB/XDR assay (Xpert MTB/XDR), FluoroType MTB, and phenotypic drug susceptibility testing (DST). Results: MTBC was detected in 426 samples using BD MAX (376 pulmonary and 50 extrapulmonary), of which 277 were culture-confirmed. Phenotypic testing confirmed 299 positive cultures on Löwenstein–Jensen (LJ) medium and 347 in BD BACTEC™ MGIT™ (BACTEC MGIT) mycobacterial growth indicator tube (BBL) liquid culture. BD MAX showed high sensitivity and specificity for extrapulmonary TB detection (93.1% and 98.4%, respectively). Resistance to isoniazid or rifampicin was identified in 11% of MTBC-positive cases, whereas 3.69% were confirmed as MDR-TB. The molecular assays effectively detected resistance-associated mutations (katG, inhA, and rpoB), with high concordance to phenotypic tests (DST) (κ = 0.69–0.89). Conclusions: This study demonstrates that molecular assays, although validated for pulmonary TB, are also reliable for extrapulmonary TB detection and drug resistance profiling. Their rapid turnaround and robust accuracy support broader implementation in routine diagnostics, especially for challenging extrapulmonary specimens where early detection is critical for targeted therapy. Full article

Background: Tuberculosis (TB) remains a leading cause of mortality worldwide, particularly in low- and middle-income countries. The rise of multidrug-resistant TB (MDR-TB) poses significant challenges to global health. This study reviews the experience of the largest pulmonology center in Serbia, a country with low MDR-TB incidence, focusing on TB prevalence, resistance detection, and treatment strategies between 2012 and 2021. Methods: We retrospectively analyzed a total of 1239 patients who were diagnosed and treated for TB in the period from 2012 to 2021 at University Clinical Center of Serbia. Results: Drug resistance was identified in 21 patients (1.7%), with the highest resistance to rifampicin (1.4%) and isoniazid (1.3%). Pyrazinamide and streptomycin resistance were detected in only a few cases. Patients with resistant TB were younger on average, though the difference was not statistically significant (46.4 ± 19.1 vs. 53.6 ± 18.4, p = 0.079). Prior TB history was more frequent in the resistant group, almost reaching statistical significance (4 vs. 82, p = 0.052). Conclusions: These findings underscore the critical importance of sustained surveillance, particularly of latent and drug-resistant TB forms, in alignment with the World Health Organization’s (WHO) TB control strategy to preserve Serbia’s low-incidence status. Moreover, given Serbia’s strategic location on a major migration route, there is an elevated risk of new TB cases emerging and potential shifts in TB-drug-resistance patterns developing in the future. Full article

Selene-ethylenelacticamide derivatives have been suggested as promising scaffolds with leishmanicidal activity. In this work, we demonstrated, for the first time, the effectiveness of selene-ethylenelacticamide derivatives against mycobacteria. Firstly, selene-ethylenelacticamides inhibited the growth of laboratory strains of Mycobacterium tuberculosis with MIC values ranging from 10 to 20 µM. Importantly, three derivatives were active against two multi-drug-resistant clinical isolates of M. tuberculosis with MIC values similar to pan-sensitive strains. In addition, NC31 and NC34 displayed an improved activity compared to the group treated with isoniazid in the six-week nutrient-starved M. tuberculosis cultures. Moreover, in toxicity studies, NC34 did not significantly affect the viability of both Vero E6 and HepG2 cell lines. NC34 did not affect Artemia salina nauplii survival at concentrations lower than 100 µM. Importantly, NC34 displayed a synergistic effect when combined with rifampicin. Molecular docking simulations were used to evaluate Mycobacterium tuberculosis DprE1 and dihydrofolate reductase enzymes as putative targets of selene-ethylenelacticamides, mechanisms that could contribute to the antitubercular activity. Our findings reveal that NC34 may represent a hit for further drug optimization and for future preclinical development as a new anti-mycobacterial agent, especially in cases of resistant and/or dormant forms of tuberculosis. Full article

Background/Objectives: Tuberculosis (TB), caused by Mycobacterium tuberculosis (M. tuberculosis), remains a leading cause of death from infectious diseases globally. The treatment of active TB relies on first- and second-line drugs, however, the emergence of drug resistance poses a significant challenge to global TB control efforts. Recent advances in whole-genome sequencing combined with machine learning have shown promise in predicting drug resistance. This study aimed to evaluate the performance of four machine learning models in classifying resistance to ethambutol, isoniazid, and rifampicin in M. tuberculosis isolates. Methods: Four machine learning models—Extreme Gradient Boosting Classifier (XGBC), Logistic Gradient Boosting Classifier (LGBC), Gradient Boosting Classifier (GBC), and an Artificial Neural Network (ANN)—were trained using a Variant Call Format (VCF) dataset preprocessed by the CRyPTIC consortium. Three datasets were used: the original dataset, a principal component analysis (PCA)-reduced dataset, and a dataset prioritizing significant mutations identified by the XGBC model. The models were trained and tested across these datasets, and their performance was compared using sensitivity, specificity, Precision, F1-scores and Accuracy. Results: All models were applied to the PCA-reduced dataset, while the XGBC model was also evaluated using the mutation-prioritized dataset. The XGBC model trained on the original dataset outperformed the others, achieving sensitivity values of 0.97, 0.90, and 0.94; specificity values of 0.97, 0.99, and 0.96; and F1-scores of 0.93, 0.94, and 0.92 for ethambutol, isoniazid, and rifampicin, respectively. These results demonstrate the superior accuracy of the XGBC model in classifying drug resistance. Conclusions: The study highlights the effectiveness of using a binary representation of mutations to train the XGBC model for predicting resistance and susceptibility to key TB drugs. The XGBC model trained on the original dataset demonstrated the highest performance among the evaluated models, suggesting its potential for clinical application in combating drug-resistant tuberculosis. Further research is needed to validate and expand these findings for broader implementation in TB diagnostics. Full article

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. Full article

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains one of the leading infectious causes of death globally, with drug resistance presenting a significant challenge to control efforts. The interplay between type 2 diabetes mellitus (T2DM) and TB introduces additional complexity, as T2DM triples the risk of active TB and exacerbates drug resistance development. This review explores how T2DM-induced metabolic and immune dysregulation fosters the survival of Mtb, promoting persistence and the emergence of multidrug-resistant strains. Mechanisms such as efflux pump activation and the subtherapeutic levels of isoniazid and rifampicin in T2DM patients are highlighted as key contributors to resistance. We discuss the dual syndemics of T2DM–TB, emphasizing the role of glycemic control and innovative therapeutic strategies, including efflux pump inhibitors and host-directed therapies like metformin. This review underscores the need for integrated diagnostic, treatment, and management approaches to address the global impact of T2DM–TB comorbidity and drug resistance. Full article

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. Full article

The incidence of Mycobacterium marinum infection is on the rise; however, the existing drug treatment cycle is lengthy and often requires multi-drug combination. Therefore, there is a need to develop new and effective anti-M. marinum drugs. Cochliomycin A, a 14-membered resorcylic acid lactone with an acetonide group at C-5′ and C-6′, exhibits a wide range of antimicrobial, antimalarial, and antifouling activities. To further explore the effect of this structural change at C-5′ and C-6′ on this compound’s activity, we synthesized a series of compounds with a structure similar to that of cochliomycin A, bearing ketal groups at C-5′ and C-6′. The R/S configuration of the diastereoisomer at C-13′ was further determined through an NOE correlation analysis of CH₃ or CH₂ at the derivative C-13′ position and the H-5′ and H-6′ by means of a 1D NOE experiment. Further comparative ¹H NMR analysis of diastereoisomers showed the difference in the chemical shift (δ) value of the diastereoisomers. The synthetic compounds were screened for their anti-microbial activities in vitro. Compounds 15–24 and 28–35 demonstrated promising activity against M. marinum, with MIC₉₀ values ranging from 70 to 90 μM, closely approaching the MIC₉₀ of isoniazid. The preliminary structure–activity relationships showed that the ketal groups with aromatic rings at C-5′ and C-6′ could enhance the inhibition of M. marinum. Further study demonstrated that compounds 23, 24, 29, and 30 had significant inhibitory effects on M. marinum and addictive effects with isoniazid and rifampicin. Its effective properties make it an important clue for future drug development toward combatting M. marinum resistance. Full article