SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Tuberculosis

327

Public trust in immunization is an increasingly important global health issue. Losses in confidence in vaccines and immunization programmes can lead to vaccine reluctance and refusal, risking disease outbreaks and challenging immunization goals in high- and low-income settings. National and international immunization stakeholders have called for better monitoring of vaccine confidence to identify emerging concerns before they evolve into vaccine confidence crises.

Concepts: Immune system, Public health, Vaccine, Vaccination, Tuberculosis, Mercury, State

209

Disulfides from Allium stipitatum, commonly known as Persian shallot, were previously reported to possess antibacterial properties. Analogues of these compounds, produced by S-methylthiolation of appropriate thiols using S-methyl methanethiosulfonate, exhibited antimicrobial activity, with one compound inhibiting the growth of Mycobacterium tuberculosis at 17 µM (4 mg L-1) and other compounds inhibiting Escherichia coli and multi-drug-resistant (MDR) Staphylococcus aureus at concentrations ranging between 32-138 µM (8-32 mg L-1). These compounds also displayed moderate inhibitory effects on Klebsiella and Proteus species. Whole-cell phenotypic bioassays such as the spot-culture growth inhibition assay (SPOTi), drug efflux inhibition, biofilm inhibition and cytotoxicity assays were used to evaluate these compounds. Of particular note was their ability to inhibit mycobacterial drug efflux and biofilm formation, while maintaining a high selectivity towards M. tuberculosis H37Rv. These results suggest that methyl disulfides are novel scaffolds which could lead to the development of new drugs against tuberculosis (TB).

Concepts: Microbiology, Antibiotic resistance, Tuberculosis, Mycobacterium, Mycobacterium tuberculosis, Enterobacteriaceae, Inhibitor, Disinfectant

198

Understanding Mycobacterium tuberculosis (Mtb) transmission is essential to guide efficient tuberculosis control strategies. Traditional strain typing lacks sufficient discriminatory power to resolve large outbreaks. Here, we tested the potential of using next generation genome sequencing for identification of outbreak-related transmission chains.

Concepts: DNA, Epidemiology, Molecular biology, Tuberculosis, Mycobacterium, Mycobacterium tuberculosis, Outbreak, Shotgun sequencing

195

Kwonjune Seung and Stephen Linton from the non-governmental organization EugeneBell discuss the worryingly high levels of multidrug-resistant tuberculosis they have observed in North Korea’s tuberculosis sanatoria. Please see later in the article for the Editors' Summary.

Concepts: Tuberculosis, Human rights, Non-profit organization, Joy Division

187

Background Drug-resistant tuberculosis threatens recent gains in the treatment of tuberculosis and human immunodeficiency virus (HIV) infection worldwide. A widespread epidemic of extensively drug-resistant (XDR) tuberculosis is occurring in South Africa, where cases have increased substantially since 2002. The factors driving this rapid increase have not been fully elucidated, but such knowledge is needed to guide public health interventions. Methods We conducted a prospective study involving 404 participants in KwaZulu-Natal Province, South Africa, with a diagnosis of XDR tuberculosis between 2011 and 2014. Interviews and medical-record reviews were used to elicit information on the participants' history of tuberculosis and HIV infection, hospitalizations, and social networks. Mycobacterium tuberculosis isolates underwent insertion sequence (IS)6110 restriction-fragment-length polymorphism analysis, targeted gene sequencing, and whole-genome sequencing. We used clinical and genotypic case definitions to calculate the proportion of cases of XDR tuberculosis that were due to inadequate treatment of multidrug-resistant (MDR) tuberculosis (i.e., acquired resistance) versus those that were due to transmission (i.e., transmitted resistance). We used social-network analysis to identify community and hospital locations of transmission. Results Of the 404 participants, 311 (77%) had HIV infection; the median CD4+ count was 340 cells per cubic millimeter (interquartile range, 117 to 431). A total of 280 participants (69%) had never received treatment for MDR tuberculosis. Genotypic analysis in 386 participants revealed that 323 (84%) belonged to 1 of 31 clusters. Clusters ranged from 2 to 14 participants, except for 1 large cluster of 212 participants (55%) with a LAM4/KZN strain. Person-to-person or hospital-based epidemiologic links were identified in 123 of 404 participants (30%). Conclusions The majority of cases of XDR tuberculosis in KwaZulu-Natal, South Africa, an area with a high tuberculosis burden, were probably due to transmission rather than to inadequate treatment of MDR tuberculosis. These data suggest that control of the epidemic of drug-resistant tuberculosis requires an increased focus on interrupting transmission. (Funded by the National Institute of Allergy and Infectious Diseases and others.).

Concepts: HIV, AIDS, Immune system, Infectious disease, Tuberculosis, South Africa, Tuberculosis treatment, Extensively drug-resistant tuberculosis

176

In a Guest Editorial on World TB Day, Madhukar Pai and Puneet Dewan identify programmatic and policy changes needed to end TB by 2035.

Concepts: Tuberculosis

171

Mycobacteria are shaped by a thick envelope made of an array of uniquely structured lipids and polysaccharides. However, the spatial organizations of these molecules remain unclear. Here we show that exposure to an esterase from Mycobacterium smegmatis (Msmeg_1529), hydrolyzing the ester linkage of trehalose dimycolate (TDM) in vitro, triggers rapid and efficient lysis of Mycobacterium tuberculosis, Mycobacterium bovis BCG, and Mycobacterium marinum. Exposure to the esterase immediately releases free mycolic acids, while concomitantly depleting trehalose mycolates. Moreover, lysis could be competitively inhibited by an excess of purified TDM and was abolished by a S124A mutation affecting the catalytic activity of the esterase. These findings are consistent with an indispensible structural role of trehalose mycolates in architectural design of the exposed surface of mycobacterial envelope. Importantly, we also demonstrate that the esterase-mediated rapid lysis of M. tuberculosis significantly improves its detection in paucibacillary samples.

Concepts: Tuberculosis, Mycobacterium, Mycobacterium tuberculosis, Mycobacterium smegmatis, Mycobacterium bovis, Corynebacterineae, Acid fast bacilli, Mycobacterium marinum

171

BACKGROUND: Tuberculosis (TB) is known to disproportionately affect the most economically disadvantaged strata of society. Many studies have assessed the association between poverty and TB, but only a few have assessed the direct financial burden TB treatment and care can place on households. Patient costs can be particularly burdensome for TB-affected households in sub-Saharan Africa where poverty levels are high; these costs include the direct costs of medical and non-medical expenditures and the indirect costs of time utilizing healthcare or lost wages. In order to comprehensively assess the existing evidence on the costs that TB patients incur, we undertook a systematic review of the literature. METHODS: PubMed, EMBASE, Science Citation Index, Social Science Citation Index, EconLit, Dissertation Abstracts, CINAHL, and Sociological Abstracts databases were searched, and 5,114 articles were identified. Articles were included in the final review if they contained a quantitative measure of direct or indirect patient costs for treatment or care for pulmonary TB in sub-Saharan Africa and were published from January 1, 1994 to Dec 31, 2010. Cost data were extracted from each study and converted to 2010 international dollars (I$). RESULTS: Thirty articles met all of the inclusion criteria. Twenty-one studies reported both direct and indirect costs; eight studies reported only direct costs and one study reported only indirect costs. Depending on type of costs, costs varied from less than I$1 to almost I$600 or from a small fraction of mean monthly income for average annual income earners to over 10 times the annual income that the average person in the income-poorest 20% of the population earns. Out of the eleven types of TB patient costs identified in this review, the costs for hospitalization, medication, transportation, and care in the private sector were largest. CONCLUSION: TB patients and households in sub-Saharan Africa often incurred high costs when utilizing TB treatment and care, both within and outside of Directly Observed Therapy Short-course (DOTS) programs. It is likely that for many households, TB treatment and care-related costs were “catastrophic” because the TB patient costs commonly amounted to 10% or more of per-capita incomes in the countries where the primary studies included in this review were conducted. Our results suggest that policies to decrease direct and indirect TB patient costs are urgently needed to prevent poverty due to TB treatment and care for those affected by the disease.

Concepts: Africa, Tuberculosis, Cost, Science Citation Index, Household income in the United States, Citation index, Social Sciences Citation Index

171

In Uganda, isoniazid plus ethambutol is used for 6 months (6HE) during the continuation treatment phase of new tuberculosis (TB) cases. However, the World Health Organization (WHO) recommends using isoniazid plus rifampicin for 4 months (4HR) instead of 6HE. We compared the impact of a continuation phase using 6HE or 4HR on total cost and expected mortality from the perspective of the Ugandan national health system.

Concepts: Health economics, Costs, Tuberculosis, World Health Organization, Pharmacoeconomics, Tuberculosis treatment, Isoniazid, Ethambutol

171

Acute HIV infection (prior to antibody seroconversion) represents a high-risk window for HIV transmission. Development of a test to detect acute infection at the point-of-care is urgent.

Concepts: HIV, AIDS, Immune system, Infectious disease, Africa, Tuberculosis, Cytomegalovirus, Acute HIV infection