SciCombinator

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Concept: Mycobacterium africanum

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Background: Extrapulmonary tuberculosis (EPTB) constitutes about 10% to 20% of all cases of tuberculosis in immunocompetent patients and more than 50% of the cases in HIV-positive individuals worldwide. Little information is available on the clonal diversity of Mycobacterium species in Ethiopia from EPTB. Methods: This study was carried out on smear-negative EPTB patients to molecularly characterize Mycobacterium tuberculosis complex strains. A questionnaire, smear staining, culture, deletion typing, and spoligotyping were employed. Results: The proportional distribution of EPTB and isolates did not vary substantially (p > 0.05) amongst the socio-demographic parameters considered in the current investigation. Out of 98 fine needle aspirates processed for culture, 36.7% (36/98) were positive for mycobacterial growth. Further speciation of those culture-positive isolates showed that 88.9% were M. tuberculosis and the remaining could be non-tuberculous mycobacterial species. Spoligotyping revealed 16 clusters out of which 2 were new to the SITVIT database. The most dominant spoligotypes were SIT54, SIT53, and SIT149 in decreasing order. SIT54, SIT134, SIT173, SIT345, SIT357, SIT926, SIT91088, and SIT1580 were reported for the first time in Ethiopia. The family with the highest frequency identified was M. tuberculosis family T1, followed by family 33. Most of the strains belonged to Euro-American (61.4%) and Indo-Oceanic (36.3%) lineages. Conclusions: The present study shows the importance of M. tuberculosis as a major cause of EPTB in the study area. Moreover, the majority of isolates of M. tuberculosis were found in clusters, suggesting the possibility of the existence of recent transmission. This warrants strengthening of the control programs for EPTB in the study area.

Concepts: Tuberculosis, Mycobacterium, Mycobacterium tuberculosis, Mycobacterium avium complex, Corynebacterineae, Acid fast bacilli, Mycobacterium africanum, Mycobacterium tuberculosis complex

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MPT64 rapid speciation tests are increasingly being used in diagnosis of tuberculosis (TB). Mycobacterium africanum West Africa 2 (Maf 2) remains an important cause of TB in West Africa and causes one third of disease in The Gambia. Since the introduction of MPT64 antigen tests, a higher than expected rate of suspected non-tuberculous mycobacteria (NTM) was seen among AFB smear positive TB suspects, which led us to prospectively assess sensitivity of the MPT64 antigen test in our setting.

Concepts: Africa, Tuberculosis, Mycobacterium, West Africa, Ghana, The Gambia, Atlantic slave trade, Mycobacterium africanum

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 There is an urgent need for an improved TB vaccine. The lack of a validated correlate of protection slows progress in achieving this goal. A human mycobacterial challenge model, using Bacille Calmette-Guérin (BCG) as a surrogate for a Mycobacterium tuberculosis challenge, would facilitate vaccine selection for field efficacy testing. Optimisation of this model is required.

Concepts: Tuberculosis, Mycobacterium, Mycobacterium tuberculosis, Efficacy, Mycobacterium bovis, Corynebacterineae, Mycobacterium africanum

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Nigeria is ranked in the top five countries for tuberculosis deaths worldwide. This study investigated the mycobacterial agents associated with presumptive clinical pulmonary tuberculosis (TB) in Nigeria and evaluated the pattern and frequency of mycobacterial infections over twelve calendar months period.

Concepts: Infectious disease, Tuberculosis, Mycobacterium, Mycobacterium tuberculosis, Mycobacterium bovis, Mycobacterium africanum

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Epidemiological differences exist between Mycobacterium africanum (Maf)- and Mycobacterium tuberculosis (Mtb)-infected patients, but to date, contributing host factors have not been characterised. We analysed clinical outcomes, as well as soluble markers and gene expression profiles in unstimulated, and ESAT6/CFP-10-, whole-Maf- and Mtb-stimulated blood samples of 26 Maf- and 49 Mtb-HIV-negative tuberculosis patients before, and after 2 and 6 months of anti-tuberculosis therapy. Before treatment, both groups had similar clinical parameters, but differed in few cytokines concentration and gene expression profiles. Following treatment the body mass index, skinfold thickness and chest X-ray scores showed greater improvement in the Mtb- compared to Maf-infected patients, after adjusting for age, sex and ethnicity (p = 0.02; 0.04 and 0.007, respectively). In addition, in unstimulated blood, IL-12p70, IL12A and TLR9 were significantly higher in Maf-infected patients, while IL-15, IL-8 and MIP-1α were higher in Mtb-infected patients. Overnight stimulation with ESAT-6/CFP-10 induced significantly higher levels of IFN-γ and TNF-α production, as well as gene expression of CCL4, IL1B and TLR4 in Mtb- compared to Maf-infected patients. Our study confirms differences in clinical features and immune genes expression and concentration of proteins associated with inflammatory processes between Mtb- and Maf-infected patients following anti-tuberculosis treatment These findings have public health implications for treatment regimens, and biomarkers for tuberculosis diagnosis and susceptibility.

Concepts: DNA, Gene, Gene expression, Organism, Tuberculosis, Body mass index, Mycobacterium, Mycobacterium africanum

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Tuberculosis infection, disease and mortality are all less common at high than low altitude and ascent to high altitude was historically recommended for treatment. The immunological and mycobacterial mechanisms underlying the association between altitude and tuberculosis are unclear. We studied the effects of altitude on mycobacteria and antimycobacterial immunity.

Concepts: Immune system, Disease, Infectious disease, Tuberculosis, The Association, Mycobacterium, Mycobacterium tuberculosis, Mycobacterium africanum

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In-cell NMR spectroscopy was used to screen for drugs that disrupt the interaction between prokaryotic ubiquitin like protein, Pup, and mycobacterial proteasome ATPase, Mpa. This interaction is critical for Mycobacterium tuberculosis resistance against nitric oxide (NO) stress; interruption of this process was proposed as a mechanism to control latent infection. Three compounds isolated from the NCI Diversity set III library rescued the physiological proteasome substrate from degradation suggesting that the proteasome degradation pathway was selectively targeted. Two of the compounds bind to Mpa with submicromolar to nanomolar affinity, and all three exhibit potency towards mycobacteria comparable to antibiotics currently available on the market, inhibiting growth in the low micromolar range.

Concepts: Microbiology, Virus, Tuberculosis, Mycobacterium, Mycobacterium tuberculosis, Corynebacterineae, Mycobacterium africanum

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A 26-year-old HIV-negative male from Ghana was treated for cervical, intrathoracic and abdominal lymph node tuberculosis (TB) and tuberculous hepatitis. Penetration of the thoracic trachea by a mediastinal lymph node had caused bronchomucosal TB. Sputum culture grew M. africanum, sensitive to all first-line antituberculous drugs. Four weeks after the beginning of directly observed treatment with isoniazid, rifampin, pyrazinamide and ethambutol, the right cervical lymph node increased in size, liquefied and caused a spontaneous fistula. A biopsy of the necrotized lymph node revealed rare acid-fast bacilli with a positive PCR for Mycobacterium tuberculosis complex. After debridement, vacuum-assisted closure therapy was performed for 6 weeks. Five months after the beginning of antituberculous therapy, a second paradoxical reaction occurred, with painful swelling of two contralateral supraclavicular lymph nodes. Extirpation of one node yielded a positive PCR for M. tuberculosis complex; the culture was negative. Antituberculous treatment was continued, and additional treatment with oral prednisolone 20 mg daily for 1 month tapering over 10 weeks was introduced, resulting in a decrease in lymphadenopathy. Antituberculous treatment was continued for a total of 9 months. The outcome was favorable, no further lymphadenopathy occurred over the following 6 months.

Concepts: Tuberculosis, Mycobacterium, Mycobacterium tuberculosis, Ziehl-Neelsen stain, Tuberculosis treatment, Acid fast bacilli, Rifampicin, Mycobacterium africanum

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Mycobacterium indicus pranii (MIP) is a potent vaccine candidate against tuberculosis (TB) as it has demonstrated significant protection in animal models of tuberculosis as well as in clinical trials. Higher protective efficacy of MIP against TB as compared to BCG provoked the efforts to gain insight into the molecular mechanisms underlying MIP mediated protection against Mycobacterium tuberculosis (M.tb). Autophagy, initially described as a cell survival mechanism during starvation, also plays a key role in host resistance to M.tb. Virulent mycobacteria like M.tb, suppresses host autophagy response to increase its survival in macrophages. Since mycobacterial species have been shown to vary widely in their autophagy-inducing properties, in the present study, we examined the autophagy inducing efficacy of MIP and its role in MIP-mediated protection against M.tb. MIP was found to be potent inducer of autophagy in macrophages. Induced autophagy was responsible for reversal of the phagosome maturation block and phagolysosome fusion inhibition in M.tb infected macrophages, which ultimately lead to significantly enhanced clearance of M.tb from the macrophages. This is an important study which further delineated the underlying mechanisms for significant immunotherapeutic activity observed in TB patients / animal models of tuberculosis, given MIP therapy along with chemotherapy.

Concepts: HIV, Phagosome, Tuberculosis, Mycobacterium, Mycobacterium tuberculosis, Bacillus Calmette-Guérin, Induced demand, Mycobacterium africanum