Tuberculosis最新文献

Mycobacteroides abscessus (Mab, also known as Mycobacterium abscessus) causes opportunistic pulmonary and soft tissue infections that are difficult to cure with existing treatments. Omadacycline, a new tetracycline antibiotic, exhibits potent in vitro and in vivo activity against Mab. As regimens containing multiple antibiotics are required to produce a durable cure for Mab disease, we assessed efficacies of three three-drug combinations in a pre-clinical mouse model of pulmonary Mab disease to identify companion drugs with which omadacycline exhibits the highest efficacy. Additionally, we assessed the susceptibility of Mab recovered from mouse lungs after four weeks of exposure to the three triple-drug regimens. Among the three-drug regimens, omadacycline + imipenem + amikacin produced the largest reduction in Mab burden, whereas omadacycline + imipenem + linezolid exhibited the most effective early bactericidal activity. Omadacycline + linezolid + clofazimine, a regimen that can be administered orally, lacked early bactericidal activity but produced a gradual reduction in the lung Mab burden over time. The robust efficacy exhibited by these three regimens in the mouse model supports their further evaluation in patients with Mab lung disease. As we were unable to isolate drug-resistant Mab mutants at the completion of four weeks of treatment, these triple-drug combinations show promise of producing durable cure and minimizing selection of resistant mutants.

Setting

Diagnosing osteoarticular tuberculosis (OATB) and detecting drug resistance is a challenge in an endemic country like India.

Objective

Truenat MTB Plus assay (TruPlus), a chip-based portable machine, was compared with GeneXpert Ultra (GxUltra) for diagnosing drug-resistant OATB.

Design

115 synovial fluid and pus specimens [22 culture-positive confirmed, 58 culture-negative clinically-suspected, 35 non-TB controls] processed between 2017 and 2023 were subjected to TruPlus, GxUltra and multiplex-PCR for diagnosing OATB. They were further screened for rifampicin resistance using TruRif chip. The performance was evaluated against composite reference standard, phenotypic drug susceptibility testing and rpoB gene sequencing.

Results

TruPlus, GxUltra and MPCR detected 77.5 %, 71.25 %, and 83.75 %, cases of OATB, respectively. TruPlus detected five additional cases missed by GxUltra. The performance of TruPlus was comparable to GxUltra (p = 0.074) and to MPCR (p = 0.074), while performance of GxUltra was significantly inferior to MPCR (p = 0.004). The overall agreement with reference standard was substantial for TruPlus and MPCR and moderate for GxUltra. Both TruRif and GxUltra reported 4 cases as rifampicin resistant.

Conclusion

TruPlus along with TruRif offers better sensitivity than GxUltra. Its compact and portable platform allows wider application in peripheral settings, thus making it a pragmatic solution for diagnosing OATB and its drug resistance.

Tuberculosis (TB) today remains the leading cause of global deaths due to infectious bacterial pathogens. The Bacillus Calmette-Guérin (BCG) vaccine is the only vaccine clinically used to prevent TB. However, its limitations in preventing latent infection and TB reactivation mean that it does not provide comprehensive protection. In this study, we successfully constructed and expressed the multistage fusion protein, SHR3, and used whole blood IFN-γ release assay (WBIA) with flow cytometry to detect antigen specificity, further confirmed by enzyme-linked immunosorbent assay (ELISA). SHR3 and its subfractional proteins stimulated the level of IFN-γ production by lymphocytes from M. tb-infected patients, inducing the production of single-positive and double-positive CD4⁺ and CD8⁺ T cells with IFN-γ and IL-2, at levels significantly higher than those of healthy controls. The fusion protein and complex adjuvant group (SHR3/DMT) induced mice to produce significantly higher levels of IgG antibodies and their subclasses, with IgG2a/IgG1 results showing a convergent Th1-type response; mice in the BCG + SHR3/DMT group induced secretion of the highest levels of IL-2, and TNF-α, irrespective of stimulation with purified protein derivative or SHR3. These findings suggest that SHR3/DMT could be a potential subunit vaccine candidate that may serve as an effective booster vaccine after BCG primary immunization.

Persistence of Mycobacterium tuberculosis (Mtb) is one of the challenges to successful treatment of tuberculosis (TB). In vitro models of non-replicating Mtb are used to test the efficacy of new molecules against Mtb persisters. The H37Ra strain is attenuated for growth in macrophages and mice. We validated H37Ra-infected immunocompetent mice for testing anti-TB molecules against slow/non-replicating Mtb in vivo. Swiss mice were infected intravenously with H37Ra and monitored for CFU burden and histopathology for a period of 12 weeks. The bacteria multiplied at a slow pace reaching a maximum load of ∼10⁶ in 8–12 weeks depending on the infection dose, accompanied by time and dose-dependent histopathological changes in the lungs. Surprisingly, four-weeks of treatment with isoniazid-rifampicin-ethambutol-pyrazinamide combination caused only 0.4 log₁₀ and 1 log₁₀ reduction in CFUs in lungs and spleen respectively. The results show that ∼40 % of the H37Ra bacilli in lungs are persisters after 4 weeks of anti-TB therapy. Isoniazid/rifampicin monotherapy also showed similar results. A combination of bedaquiline and isoniazid reduced the CFU counts to <200 (limit of detection), compared to ∼5000 CFUs by isoniazid alone. The study demonstrates an in vivo model of Mtb persisters for testing new leads using a BSL-2 strain.

To evaluate the diagnostic performance of Xpert MTB/RIF Ultra (Ultra) for the diagnosis of extrapulmonary tuberculosis (EPTB) from different types of extrapulmonary specimens in comparison with culture and composite microbiological reference standard (CRS). A total of 240 specimens were prospectively collected from presumptive EPTB patients between July 2021–January 2022 and tested by Ultra, Xpert, culture and acid-fast bacilli (AFB) smear microscopy. Out of 240 specimens, 35.8 %, 20.8 %, 11.3 %, and 7.1 % were detected as Mycobacterium tuberculosis complex by Ultra, Xpert, culture and AFB microscopy, respectively. An additional 15.0 % cases were detected by Ultra compared to Xpert MTB/RIF (Xpert) assay. A total of 28 (11.7 %) cases were identified as ‘trace’ category by Ultra with indeterminate rifampicin resistance result; of which 36.4 % were clinically confirmed as EPTB. Compared to culture, the sensitivity and specificity of Ultra and Xpert were 100 % and 72.3 %; 92.6 % and 88.3 %, respectively. In comparison with CRS, these were respectively: 98.9 % and 100 %; 57.5 % and 100 %. For individual category of specimens, sensitivity of Ultra was 100 % with varying specificity. We found that Ultra was highly sensitive for the rapid diagnosis of EPTB and has extensive potential over current diagnostics in high TB burden countries, but ‘trace’ results should be interpreted with caution.

Mycobacterium tuberculosis (Mtb) has evolved sophisticated surveillance mechanisms to neutralize the ROS-induces toxicity which otherwise would degrade a variety of biological molecules including proteins, nucleic acids and lipids. In the present study, we find that Mtb lacking the Rv0495c gene (ΔRv0495c) is presented with a highly oxidized cytosolic environment. The superoxide-induced lipid peroxidation resulted in altered colony morphology and loss of membrane integrity in ΔRv0495c. As a consequence, ΔRv0495c demonstrated enhanced susceptibility when exposed to various host-induced stress conditions. Further, as expected, we observed a mutant-specific increase in the abundance of transcripts that encode proteins involved in antioxidant defence. Surprisingly, despite showing a growth defect phenotype in macrophages, the absence of the Rv0495c enhanced the pathogenicity and augmented the ability of the Mtb to grow inside the host. Additionally, our study revealed that Rv0495c-mediated immunomodulation by the pathogen helps create a favorable niche for long-term survival of Mtb inside the host. In summary, the current study underscores the fact that the truce in the war between the host and the pathogen favours long-term disease persistence in tuberculosis. We believe targeting Rv0495c could potentially be explored as a strategy to potentiate the current anti-TB regimen.

The effect of acetylator status on the exposure to isoniazid in plasma and CSF in tuberculous meningitis (TBM) patients remains largely unexplored. Here, we describe isoniazid exposures and acetylator status of 48 subjects in the ReDEFINe study (NCT02169882). Fifty percentwere fast (half-life <130 min) or slow (half-life >130 min) acetylators. Slow acetylators had higher AUC_0-24, C_max and CSF concentrations than fast acetylators (GM AUC_0-24 25.5 vs 10.6 mg/L*h, p < 0.001); plasma C_max 5.5 vs 3.6 mg/L, p = 0.023; CSF concentration 1.9 vs 1.1 mg/L, p = 0.008). Higher isoniazid doses may benefit fast acetylators in TBM.

Diagnosis of TB at early stages of HIV infection may lead to timely intervention for improving patient outcome. Antibodies to Mycobacterium tuberculosis recombinant RpfB protein and two immunodominant peptides of Rpf B protein were evaluated in the sera of HIV ⁺TB⁺, HIV⁺ and HIV⁻ pulmonary TB patients by ELISA. Serum antibodies from 90 % and 65 % of HIV⁺TB⁺ patients reacted to recombinant RpfB protein and synthetic peptide RpfP1 respectively. Overall, this study shows that resuscitation promoting factor B elicits humoral antibody response in HIV⁺TB⁺ co-infected individuals and be proposed as a potential biomarker for diagnosis of HIV⁺TB⁺ patients, however further longitudinal follow up studies are warranted.

Paradoxical reaction (PR) in tuberculous meningitis (TBM) is a major management issue. We report mRNA profiling of cytokines to understand PR in HIV-uninfected TBM patients. 72 patients with TBM were included, and their clinical, MRI, and mRNA profiling of tumor necrosis factor (TNF) α, interleukin (IL) 6, IL10 and interferon (IFN) γ genes in the peripheral blood mononuclear cells were done at admission and 6 weeks of antitubercular treatment. Cytokine profiling was done using reverse transcriptase polymerase chain reaction. PR was defined if repeat MRI at 6 weeks revealed new or increase in exudates, tuberculoma, hydrocephalus or infarctions. Outcome was defined at 6 months using modified Rankin Scale (mRS), and categorized as death, poor and good. 44 (61.1 %) patients had PR, and 28 (38.9 %) had paradoxical tuberculoma (PT). The expression of IL6 and TNFα genes were higher in PR and PT groups. Stage of meningitis and hydrocephalus at admission predicted PR. Patients with PR and PT had more frequently poor outcome.

About three-fifth HIV-uninfected TBM patients have PR and two-fifth have PT. Paradoxical reaction is associated with higher expression of IL6 and TNFα. Patients with severe meningitis with hydrocephalus develop PR more frequently.