The Arctic Plant Aboveground Biomass Synthesis Dataset.

Plant biomass is a fundamental ecosystem attribute that is sensitive to rapid climatic changes occurring in the Arctic. Nevertheless, measuring plant biomass in the Arctic is logistically challenging and resource intensive. Lack of accessible field data hinders efforts to understand the amount, composition, distribution, and changes in plant biomass in these northern ecosystems. Here, we present The Arctic plant aboveground biomass synthesis dataset, which includes field measurements of lichen, bryophyte, herb, shrub, and/or tree aboveground biomass (g m-2) on 2,327 sample plots from 636 field sites in seven countries. We created the synthesis dataset by assembling and harmonizing 32 individual datasets. Aboveground biomass was primarily quantified by harvesting sample plots during mid- to late-summer, though tree and often tall shrub biomass were quantified using surveys and allometric models. Each biomass measurement is associated with metadata including sample date, location, method, data source, and other information. This unique dataset can be leveraged to monitor, map, and model plant biomass across the rapidly warming Arctic.

Variance components of sex determination in the copepod Tigriopus californicus estimated from a pedigree analysis.

Extensive theory exists regarding population sex ratio evolution that predicts equal sex ratio (when parental investment is equal). In most animals, sex chromosomes determine the sex of offspring, and this fixed genotype for sex has made theory difficult to test since genotypic variance for the trait (sex) is lacking. It has long been argued that the genotype has become fixed in most animals due to the strong selection for equal sex ratios. The marine copepod Tigriopus californicus has no sex chromosomes, multiple genes affecting female brood sex ratio, and a brood sex ratio that responds to selection. The species thus provides an opportune system in which to test established sex ratio theory. In this paper, we further our exploration of polygenic sex determination in T. californicus using an incomplete diallel crossing design for analysis of the variance components of sex determination in the species. Our data confirm the presence of extra-binomial variance for sex, further confirming that sex is not determined through simple Mendelian trait inheritance. In addition, our crosses and backcrosses of isofemale lines selected for biased brood sex ratios show intermediate phenotypic means, as expected if sex is a threshold trait determined by an underlying "liability" trait controlled by many genes of small effects. Furthermore, crosses between families from the same selection line had similar increases in phenotypic variance as crosses between families from different selection lines, suggesting families from artificial selection lines responded to selection pressure through different underlying genetic bases. Finally, we estimate heritability of an individual to be male or female on the observed binary scale as 0.09 (95% CI: 0.034-0.14). This work furthers our accumulating evidence for polygenic sex determination in T. californicus laying the foundation for this as a model species in future studies of sex ratio evolution theory.

Building Integrated Testing Programs for Infectious Diseases.

In the past 2 decades, testing services for diseases such as human immunodeficiency virus (HIV), tuberculosis, and malaria have expanded dramatically. Investments in testing capacity and supportive health systems have often been disease specific, resulting in siloed testing programs with suboptimal capacity, reduced efficiency, and limited ability to introduce additional tests or respond to new outbreaks. Emergency demand for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing overcame these silos and demonstrated the feasibility of integrated testing. Moving forward, an integrated public laboratory infrastructure that services multiple diseases, including SARS-CoV-2, influenza, HIV, tuberculosis, hepatitis, malaria, sexually transmitted diseases, and other infections, will help improve universal healthcare delivery and pandemic preparedness. However, integrated testing faces many barriers including poorly aligned health systems, funding, and policies. Strategies to overcome these include greater implementation of policies that support multidisease testing and treatment systems, diagnostic network optimization, bundled test procurement, and more rapid spread of innovation and best practices across disease programs.

Progress in scale up of HIV viral load testing in select sub-Saharan African countries 2016-2018.

INTRODUCTION: We assessed progress in HIV viral load (VL) scale up across seven sub-Saharan African (SSA) countries and discussed challenges and strategies for improving VL coverage among patients on anti-retroviral therapy (ART). METHODS: A retrospective review of VL testing was conducted in Côte d'Ivoire, Kenya, Lesotho, Malawi, Namibia, Tanzania, and Uganda from January 2016 through June 2018. Data were collected and included the cumulative number of ART patients, number of patients with ≥ 1 VL test result (within the preceding 12 months), the percent of VL test results indicating viral suppression, and the mean turnaround time for VL testing. RESULTS: Between 2016 and 2018, the proportion of PLHIV on ART in all 7 countries increased (range 5.7%-50.2%). During the same time period, the cumulative number of patients with one or more VL test increased from 22,996 to 917,980. Overall, viral suppression rates exceeded 85% for all countries except for Côte d'Ivoire at 78% by June 2018. Reported turnaround times for VL testing results improved in 5 out of 7 countries by between 5.4 days and 27.5 days. CONCLUSIONS: These data demonstrate that remarkable progress has been made in the scale-up of HIV VL testing in the seven SSA countries.

The performance of using dried blood spot specimens for HIV-1 viral load testing: A systematic review and meta-analysis.

BACKGROUND: Accurate routine HIV viral load testing is essential for assessing the efficacy of antiretroviral treatment (ART) regimens and the emergence of drug resistance. While the use of plasma specimens is the standard for viral load testing, its use is restricted by the limited ambient temperature stability of viral load biomarkers in whole blood and plasma during storage and transportation and the limited cold chain available between many health care facilities in resource-limited settings. Alternative specimen types and technologies, such as dried blood spots, may address these issues and increase access to viral load testing; however, their technical performance is unclear. To address this, we conducted a meta-analysis comparing viral load results from paired dried blood spot and plasma specimens analyzed with commonly used viral load testing technologies. METHODS AND FINDINGS: Standard databases, conferences, and gray literature were searched in 2013 and 2018. Nearly all studies identified (60) were conducted between 2007 and 2018. Data from 40 of the 60 studies were included in the meta-analysis, which accounted for a total of 10,871 paired dried blood spot:plasma data points. We used random effects models to determine the bias, accuracy, precision, and misclassification for each viral load technology and to account for between-study variation. Dried blood spot specimens produced consistently higher mean viral loads across all technologies when compared to plasma specimens. However, when used to identify treatment failure, each technology compared best to plasma at a threshold of 1,000 copies/ml, the present World Health Organization recommended treatment failure threshold. Some heterogeneity existed between technologies; however, 5 technologies had a sensitivity greater than 95%. Furthermore, 5 technologies had a specificity greater than 85% yet 2 technologies had a specificity less than 60% using a treatment failure threshold of 1,000 copies/ml. The study's main limitation was the direct applicability of findings as nearly all studies to date used dried blood spot samples prepared in laboratories using precision pipetting that resulted in consistent input volumes. CONCLUSIONS: This analysis provides evidence to support the implementation and scale-up of dried blood spot specimens for viral load testing using the same 1,000 copies/ml treatment failure threshold as used with plasma specimens. This may support improved access to viral load testing in resource-limited settings lacking the required infrastructure and cold chain storage for testing with plasma specimens.

A Partially Multiplexed HIV Drug Resistance (HIVDR) Assay for Monitoring HIVDR Mutations of the Protease, Reverse-Transcriptase (PRRT), and Integrase (INT).

As dolutegravir (DTG)-containing HIV regimens are scaled up globally, monitoring for HIV drug resistance (HIVDR) will become increasingly important. We designed a partially multiplexed HIVDR assay using Sanger sequencing technology to monitor HIVDR mutations in the protease, reverse-transcriptase (PRRT), and integrase (INT). A total of 213 clinical and analytical plasma and dried blood spot (DBS) samples were used in the evaluation. The assay detected a wide range of known HIV-1 subtypes and circulating recombinant forms (CRFs) of group M from 139 samples. INT accuracy showed that the average nucleotide (nt) sequence concordance was 99.8% for 75 plasma samples and 99.5% for 11 DBS samples compared with the reference sequences. The PRRT accuracy also demonstrated the average nucleotide sequence concordance was 99.5% for 57 plasma samples and 99.2% for 33 DBS samples. The major PRRT and INT DR mutations of all samples tested were concordant with those of the reference sequences using the Stanford HIV database (db). Amplification sensitivity of samples with viral load (VL) >5000 copies/mL showed plasma exceeded 95% of positivity, and DBS exceeded 90% for PRRT and INT. Samples with VL (1000 to 5000 copies/mL) showed plasma exceeded 90%, and DBS reached 88% positivity for PRRT and INT. Assay precision and reproducibility showed >99% nucleotide sequence concordance in each set of replicates for PRRT and INT. In conclusion, this HIVDR assay met WHO HIVDR assay performance criteria for surveillance, worked for plasma and DBS, used minimal sample volume, was sensitive, and was a potentially cost-effective tool to monitor HIVDR mutations in PRRT and INT. IMPORTANCE This HIVDR genotyping assay works for both plasma and DBS samples, requires low sample input, and is sensitive. This assay has the potential to be a user-friendly and cost-effective HIVDR assay because of its partially multiplexed design. Application of this genotyping assay will help HIVDR monitoring in HIV high-burdened countries using a DGT-based HIV drug regimen recommended by the U.S. President's Emergency Plan for AIDS Relief and the WHO.

Increasing fire and the decline of fire adapted black spruce in the boreal forest.

Intensifying wildfire activity and climate change can drive rapid forest compositional shifts. In boreal North America, black spruce shapes forest flammability and depends on fire for regeneration. This relationship has helped black spruce maintain its dominance through much of the Holocene. However, with climate change and more frequent and severe fires, shifts away from black spruce dominance to broadleaf or pine species are emerging, with implications for ecosystem functions including carbon sequestration, water and energy fluxes, and wildlife habitat. Here, we predict that such reductions in black spruce after fire may already be widespread given current trends in climate and fire. To test this, we synthesize data from 1,538 field sites across boreal North America to evaluate compositional changes in tree species following 58 recent fires (1989 to 2014). While black spruce was resilient following most fires (62%), loss of resilience was common, and spruce regeneration failed completely in 18% of 1,140 black spruce sites. In contrast, postfire regeneration never failed in forests dominated by jack pine, which also possesses an aerial seed bank, or broad-leaved trees. More complete combustion of the soil organic layer, which often occurs in better-drained landscape positions and in dryer duff, promoted compositional changes throughout boreal North America. Forests in western North America, however, were more vulnerable to change due to greater long-term climate moisture deficits. While we find considerable remaining resilience in black spruce forests, predicted increases in climate moisture deficits and fire activity will erode this resilience, pushing the system toward a tipping point that has not been crossed in several thousand years.

Derivation and external validation of a risk score for predicting HIV-associated tuberculosis to support case finding and preventive therapy scale-up: A cohort study.

BACKGROUND: Among people living with HIV (PLHIV), more flexible and sensitive tuberculosis (TB) screening tools capable of detecting both symptomatic and subclinical active TB are needed to (1) reduce morbidity and mortality from undiagnosed TB; (2) facilitate scale-up of tuberculosis preventive therapy (TPT) while reducing inappropriate prescription of TPT to PLHIV with subclinical active TB; and (3) allow for differentiated HIV-TB care. METHODS AND FINDINGS: We used Botswana XPRES trial data for adult HIV clinic enrollees collected during 2012 to 2015 to develop a parsimonious multivariable prognostic model for active prevalent TB using both logistic regression and random forest machine learning approaches. A clinical score was derived by rescaling final model coefficients. The clinical score was developed using southern Botswana XPRES data and its accuracy validated internally, using northern Botswana data, and externally using 3 diverse cohorts of antiretroviral therapy (ART)-naive and ART-experienced PLHIV enrolled in XPHACTOR, TB Fast Track (TBFT), and Gugulethu studies from South Africa (SA). Predictive accuracy of the clinical score was compared with the World Health Organization (WHO) 4-symptom TB screen. Among 5,418 XPRES enrollees, 2,771 were included in the derivation dataset; 67% were female, median age was 34 years, median CD4 was 240 cells/µL, 189 (7%) had undiagnosed prevalent TB, and characteristics were similar between internal derivation and validation datasets. Among XPHACTOR, TBFT, and Gugulethu cohorts, median CD4 was 400, 73, and 167 cells/µL, and prevalence of TB was 5%, 10%, and 18%, respectively. Factors predictive of TB in the derivation dataset and selected for the clinical score included male sex (1 point), ≥1 WHO TB symptom (7 points), smoking history (1 point), temperature >37.5°C (6 points), body mass index (BMI) <18.5kg/m2 (2 points), and severe anemia (hemoglobin <8g/dL) (3 points). Sensitivity using WHO 4-symptom TB screen was 73%, 80%, 94%, and 94% in XPRES, XPHACTOR, TBFT, and Gugulethu cohorts, respectively, but increased to 88%, 87%, 97%, and 97%, when a clinical score of ≥2 was used. Negative predictive value (NPV) also increased 1%, 0.3%, 1.6%, and 1.7% in XPRES, XPHACTOR, TBFT, and Gugulethu cohorts, respectively, when the clinical score of ≥2 replaced WHO 4-symptom TB screen. Categorizing risk scores into low (<2), moderate (2 to 10), and high-risk categories (>10) yielded TB prevalence of 1%, 1%, 2%, and 6% in the lowest risk group and 33%, 22%, 26%, and 32% in the highest risk group for XPRES, XPHACTOR, TBFT, and Gugulethu cohorts, respectively. At clinical score ≥2, the number needed to screen (NNS) ranged from 5.0 in Gugulethu to 11.0 in XPHACTOR. Limitations include that the risk score has not been validated in resource-rich settings and needs further evaluation and validation in contemporary cohorts in Africa and other resource-constrained settings. CONCLUSIONS: The simple and feasible clinical score allowed for prioritization of sensitivity and NPV, which could facilitate reductions in mortality from undiagnosed TB and safer administration of TPT during proposed global scale-up efforts. Differentiation of risk by clinical score cutoff allows flexibility in designing differentiated HIV-TB care to maximize impact of available resources.

HIV Viral Load Monitoring Among Patients Receiving Antiretroviral Therapy - Eight Sub-Saharan Africa Countries, 2013-2018.

One component of the Joint United Nations Programme on HIV/AIDS (UNAIDS) goal to end the HIV/AIDS epidemic by 2030, is that 95% of all persons receiving antiretroviral therapy (ART) achieve viral suppression.† Thus, testing all HIV-positive persons for viral load (number of copies of viral RNA per mL) is a global health priority (1). CDC and other U.S. government agencies, as part of the U.S. President's Emergency Plan for AIDS Relief (PEPFAR), together with other stakeholders, have provided technical assistance and supported the cost for multiple countries in sub-Saharan Africa to expand viral load testing as the preferred monitoring strategy for clinical response to ART. The individual and population-level benefits of ART are well understood (2). Persons receiving ART who achieve and sustain an undetectable viral load do not transmit HIV to their sex partners, thereby disrupting onward transmission (2,3). Viral load testing is a cost-effective and sustainable programmatic approach for monitoring treatment success, allowing reduced frequency of health care visits for patients who are virally suppressed (4). Viral load monitoring enables early and accurate detection of treatment failure before immunologic decline. This report describes progress on the scale-up of viral load testing in eight sub-Saharan African countries from 2013 to 2018 and examines the trajectory of improvement with viral load testing scale-up that has paralleled government commitments, sustained technical assistance, and financial resources from international donors. Viral load testing in low- and middle-income countries enables monitoring of viral load suppression at the individual and population level, which is necessary to achieve global epidemic control. Although there has been substantial achievement in improving viral load coverage for all patients receiving ART, continued engagement is needed to reach global targets.

Dual motor cortex and spinal cord neuromodulation improves rehabilitation efficacy and restores skilled locomotor function in a rat cervical contusion injury model.

Motor recovery after spinal cord injury is limited due to sparse descending pathway axons caudal to the injury. Rehabilitation is the primary treatment for paralysis in humans with SCI, but only produces modest functional recovery. Here, we determined if dual epidural motor cortex (M1) intermittent theta burst stimulation (iTBS) and cathodal transcutaneous spinal direct stimulation (tsDCS) enhances the efficacy of rehabilitation in improving motor function after cervical SCI. iTBS produces CST axon sprouting and tsDCS enhances M1-evoked spinal activity and muscle contractions after SCI. Rats were trained to perform the horizontal ladder task. Animals received a moderate midline C4 contusion, producing bilateral forelimb impairments. After 2 weeks, animals either received 10 days of iTBS+tsDCS or no stimulation; subsequently, all animals received 6 weeks of daily rehabilitation on the horizontal ladder task. Lesion size was not different in the two animal groups. Rehabilitation alone improved performance by a 22% reduction in skilled locomotion error rate, whereas stimulation+rehabilitation was markedly more effective (52%), and restored error rate to pre-injury levels. Stimulation+rehabilitation significantly increased CST axon length caudal to the injury and the amount of ventral horn label was positively correlated with functional improvement. The stimulation+rehabilitation group had significantly less proprioceptive afferent terminal labelling in the intermediate zone and fewer synapses on motoneurons . Afferent fiber terminal labeling was negatively correlated with motor recovery. Thus, the dual neuromodulation protocol promotes adaptive plasticity in corticospinal and proprioceptive afferents networks after contusion SCI, leading to enhanced rehabilitation efficacy and recovery of skilled locomotion.

Carbon loss from boreal forest wildfires offset by increased dominance of deciduous trees.

In boreal forests, climate warming is shifting the wildfire disturbance regime to more frequent fires that burn more deeply into organic soils, releasing sequestered carbon to the atmosphere. To understand the destabilization of carbon storage, it is necessary to consider these effects in the context of long-term ecological change. In Alaskan boreal forests, we found that shifts in dominant plant species catalyzed by severe fire compensated for greater combustion of soil carbon over decadal time scales. Severe burning of organic soils shifted tree dominance from slow-growing black spruce to fast-growing deciduous broadleaf trees, resulting in a net increase in carbon storage by a factor of 5 over the disturbance cycle. Reduced fire activity in future deciduous-dominated boreal forests could increase the tenure of this carbon on the landscape, thereby mitigating the feedback to climate warming.

A global proficiency testing programme for Xpert® MTB/RIF using dried tube specimens, 2013-2015.

BACKGROUND: Proficiency testing (PT) is an important quality assurance measure toward ensuring accurate and reliable diagnostic test results from clinical and public health laboratories. Despite the rapid expansion of the Xpert® MTB/RIF assay for the detection of tuberculosis in resource-limited settings (RLS), low-cost PT materials for Xpert MTB/RIF external quality assessment (EQA) are not widely available. OBJECTIVE: We sought to determine whether a dried tube specimen (DTS)-based PT programme would be a feasible option to support Xpert MTB/RIF EQA in RLS. METHODS: Between 2013 and 2015, the United States Centers for Disease Control and Prevention developed and conducted a voluntary EQA programme using DTS-based PT material. Eight rounds of PT, each comprising five DTS samples, were provided to enrolled testing sites. After each round, participant results were compared to expected results, scored as satisfactory or unsatisfactory, and sites were provided with performance reports. RESULTS: Programme enrolment increased from 102 testing sites in seven countries to 441 testing sites in 14 countries over the course of three years. In each PT round, approximately 90% of participating sites demonstrated satisfactory performance. In seven of the 14 enrolled countries, the proportion of sites with a satisfactory score increased between the first round of participation and the most recent round of participation. CONCLUSION: This programme demonstrated that it is possible to implement an Xpert MTB/RIF PT programme for RLS using DTS, that substantial demand for Xpert MTB/RIF PT material exists in RLS, and that country performance can improve in a DTS-based PT programme.

Risk scores for predicting early antiretroviral therapy mortality in sub-Saharan Africa to inform who needs intensification of care: a derivation and external validation cohort study.

BACKGROUND: Clinical scores to determine early (6-month) antiretroviral therapy (ART) mortality risk have not been developed for sub-Saharan Africa (SSA), home to 70% of people living with HIV. In the absence of validated scores, WHO eligibility criteria (EC) for ART care intensification are CD4 < 200/µL or WHO stage III/IV. METHODS: We used Botswana XPRES trial data for adult ART enrollees to develop CD4-independent and CD4-dependent multivariable prognostic models for 6-month mortality. Scores were derived by rescaling coefficients. Scores were developed using the first 50% of XPRES ART enrollees, and their accuracy validated internally and externally using South African TB Fast Track (TBFT) trial data. Predictive accuracy was compared between scores and WHO EC. RESULTS: Among 5553 XPRES enrollees, 2838 were included in the derivation dataset; 68% were female and 83 (3%) died by 6 months. Among 1077 TBFT ART enrollees, 55% were female and 6% died by 6 months. Factors predictive of 6-month mortality in the derivation dataset at p < 0.01 and selected for the CD4-independent score included male gender (2 points), ≥ 1 WHO tuberculosis symptom (2 points), WHO stage III/IV (2 points), severe anemia (hemoglobin < 8 g/dL) (3 points), and temperature > 37.5 °C (2 points). The same variables plus CD4 < 200/µL (1 point) were included in the CD4-dependent score. Among XPRES enrollees, a CD4-independent score of ≥ 4 would provide 86% sensitivity and 66% specificity, whereas WHO EC would provide 83% sensitivity and 58% specificity. If WHO stage alone was used, sensitivity was 48% and specificity 89%. Among TBFT enrollees, the CD4-independent score of ≥ 4 would provide 95% sensitivity and 27% specificity, whereas WHO EC would provide 100% sensitivity but 0% specificity. Accuracy was similar between CD4-independent and CD4-dependent scores. Categorizing CD4-independent scores into low (< 4), moderate (4-6), and high risk (≥ 7) gave 6-month mortality of 1%, 4%, and 17% for XPRES and 1%, 5%, and 30% for TBFT enrollees. CONCLUSIONS: Sensitivity of the CD4-independent score was nearly twice that of WHO stage in predicting 6-month mortality and could be used in settings lacking CD4 testing to inform ART care intensification. The CD4-dependent score improved specificity versus WHO EC. Both scores should be considered for scale-up in SSA.

Development of dried tube specimens for Xpert MTB/RIF proficiency testing.

BACKGROUND: Proficiency testing (PT) is part of a comprehensive quality assurance programme, which is critical to ensuring patients receive accurate and reliable diagnostic testing. Implementation of the Cepheid Xpert® MTB/RIF assay to aid in the diagnosis of tuberculosis has expanded rapidly in recent years; however, PT material for Xpert MTB/RIF is not readily available in many resource-limited settings. OBJECTIVE: To develop an accurate and precise PT material based on the dried tube specimen (DTS) method, using supplies and reagents available in most tuberculosis culture laboratories. METHODS: Dried tube specimens were produced at the United States Centers for Disease Control and Prevention from 2013 to 2015 by inactivating liquid cultures of well-characterised mycobacterial strains. Ten percent of DTS produced were tested with Xpert MTB/RIF and evaluated for accuracy and precision. RESULTS: Validation testing across eight rounds of PT demonstrated that DTS are highly accurate, achieving an average of 96.8% concordance with the Xpert MTB/RIF results from the original mycobacterial strains. Dried tube specimen testing was also precise, with cycle threshold standard deviations below two cycles when inherent test cartridge variability was low. CONCLUSION: Dried tube specimens can be produced using equipment already present in tuberculosis culture laboratories, making Xpert MTB/RIF PT scale-up more feasible in resource-limited settings. Use of DTS may fill the gap in tuberculosis laboratory access to external quality assessment, which is an essential component of a comprehensive continuous quality improvement programme.

Building and Sustaining Optimized Diagnostic Networks to Scale-up HIV Viral Load and Early Infant Diagnosis.

BACKGROUND: Progress toward meeting the UNAIDS 2014 HIV treatment (90-90-90) targets has been slow in some countries because of gaps in access to HIV diagnostic tests. Emerging point-of-care (POC) molecular diagnostic technologies for HIV viral load (VL) and early infant diagnosis (EID) may help reduce diagnostic gaps. However, these technologies need to be implemented in a complementary and strategic manner with laboratory-based instruments to ensure optimization. METHOD: Between May 2019 and February 2020, a systemic literature search was conducted in PubMed, the Cochrane Library, MEDLINE, conference abstracts, and other sources such as Unitaid, UNAIDS, WHO, and UNICEF websites to determine factors that would affect VL and EID scale-up. Data relevant to the search themes were reviewed for accuracy and were included. RESULTS: Collaborations among countries, implementing partners, and donors have identified a set of framework for the effective use of both POC-based and laboratory-based technologies in large-scale VL and EID testing programs. These frameworks include (1) updated testing policies on the operational utility of POC and laboratory-based technologies, (2) expanded integrated testing using multidisease diagnostic platforms, (3) laboratory network mapping, (4) use of more efficient procurement and supply chain approaches such as all-inclusive pricing and reagent rental, and (5) addressing systemic issues such as test turnaround time, sample referral, data management, and quality systems. CONCLUSIONS: Achieving and sustaining optimal VL and EID scale-up within tiered diagnostic networks would require better coordination among the ministries of health of countries, donors, implementing partners, diagnostic manufacturers, and strong national laboratory and clinical technical working groups.

Isoniazid and Rifampin-Resistance Mutations Associated With Resistance to Second-Line Drugs and With Sputum Culture Conversion.

BACKGROUND: Mutations in the genes inhA, katG, and rpoB confer resistance to anti-tuberculosis (TB) drugs isoniazid and rifampin. We questioned whether specific mutations in these genes were associated with different clinical and microbiological characteristics. METHODS: In a multicountry prospective cohort study of multidrug-resistant TB, we identified inhA, katG, and rpoB mutations in sputum isolates using the Hain MTBDRplus line probe assay. For specific mutations, we performed bivariate analysis to determine relative risk of baseline or acquired resistance to other TB drugs. We compared time to sputum culture conversion (TSCC) using Kaplan-Meier curves and stratified Cox regression. RESULTS: In total, 447 participants enrolled from January 2005 to December 2008 from 7 countries were included. Relative to rpoB S531L, isolates with rpoB D516V had less cross-resistance to rifabutin, increased baseline resistance to other drugs, and increased acquired fluoroquinolone resistance. Relative to mutation of katG only, mutation of inhA promoter and katG was associated with baseline extensively drug resistant (XDR) TB, increased acquired fluoroquinolone resistance, and slower TSCC (125.5 vs 89.0 days). CONCLUSIONS: Specific mutations in inhA and katG are associated with differences in resistance to other drugs and TSCC. Molecular testing may make it possible to tailor treatment and assess additional drug resistance risk according to specific mutation profile.

Effect of tuberculosis screening and retention interventions on early antiretroviral therapy mortality in Botswana: a stepped-wedge cluster randomized trial.

BACKGROUND: Undiagnosed tuberculosis (TB) remains the most common cause of HIV-related mortality. Xpert MTB/RIF (Xpert) is being rolled out globally to improve TB diagnostic capacity. However, previous Xpert impact trials have reported that health system weaknesses blunted impact of this improved diagnostic tool. During phased Xpert rollout in Botswana, we evaluated the impact of a package of interventions comprising (1) additional support for intensified TB case finding (ICF), (2) active tracing for patients missing clinic appointments to support retention, and (3) Xpert replacing sputum-smear microscopy, on early (6-month) antiretroviral therapy (ART) mortality. METHODS: At 22 clinics, ART enrollees > 12 years old were eligible for inclusion in three phases: a retrospective standard of care (SOC), prospective enhanced care (EC), and prospective EC plus Xpert (EC+X) phase. EC and EC+X phases were implemented as a stepped-wedge trial. Participants in the EC phase received SOC plus components 1 (strengthened ICF) and 2 (active tracing) of the intervention package, and participants in the EC+X phase received SOC plus all three intervention package components. Primary and secondary objectives were to compare all-cause 6-month ART mortality between SOC and EC+X and between EC and EC+X phases, respectively. We used adjusted analyses, appropriate for study design, to control for baseline differences in individual-level factors and intra-facility correlation. RESULTS: We enrolled 14,963 eligible patients: 8980 in SOC, 1768 in EC, and 4215 in EC+X phases. Median age of ART enrollees was 35 and 64% were female. Median CD4 cell count was lower in SOC than subsequent phases (184/µL in SOC, 246/µL in EC, and 241/µL in EC+X). By 6 months of ART, 461 (5.3%) of SOC, 54 (3.2%) of EC, and 121 (3.0%) of EC+X enrollees had died. Compared with SOC, 6-month mortality was lower in the EC+X phase (adjusted hazard ratio, 0.77; 95% confidence interval, 0.61-0.97, p = 0.029). Compared with EC enrollees, 6-month mortality was similar among EC+X enrollees. CONCLUSIONS: Interventions to strengthen ICF and retention were associated with lower early ART mortality. This new evidence highlights the need to strengthen ICF and retention in many similar settings. Similar to other trials, no additional mortality benefit of replacing sputum-smear microscopy with Xpert was observed. TRIAL REGISTRATION: Retrospectively registered: ClinicalTrials.gov (NCT02538952).

The effect of sputum quality and volume on the yield of bacteriologically-confirmed TB by Xpert MTB/RIF and smear.

INTRODUCTION: The World Health Organization endorsed (2010) the use of Xpert MTB/RIF and countries are shifting from smear microscopy (smear)-based to Xpert MTB/RIF-based tuberculosis (TB) diagnostic algorithms. As with smear, sputum quality may predict the likelihood of obtaining a bacteriologically-confirmed TB when using Xpert MTB/RIF. METHODS: From 08/12-11/2014, all people living with HIV were recruited at 22 clinics. For patients screened positive using the four TB symptoms their sputa were tested by Xpert MTB/RIF and smear. Laboratorians assessed and recorded sputum appearance and volume. The yield of bacteriologically-positive sputum evaluated using Xpert MTB/RIF and smear, likelihood-ratios were calculated. RESULTS: Among 6,041 patients enrolled 2,296 were presumptive TB, 1,305 (56.8%) had > 1 sputa collected and 644/1,305 (49.3%) had both Xpert MTB/RIF and smear results. Since >1 sputa collected from 644 patients 954 sputa were tested by Xpert MTB/RIF and smear. Bacteriologically-positive sputum was two-fold higher with Xpert MTB/RIF 11.4% versus smear 5.3%, p < 0.001. Sputum appearance and quantity were not predictive of bacteriologically-positive results, except volume of 2ml to < 3ml, tested by Xpert MTB/RIF LR+= 1.26 (95% CI, 1.05-1.50). CONCLUSION: Xpert MTB/RIF test yield to bacteriologically-positive sputum was superior to smear. Sputum quality and quantity, however, were not consistently predictive of bacteriologically-positive results by Xpert MTB/RIF or smear.

Independent replication of motor cortex and cervical spinal cord electrical stimulation to promote forelimb motor function after spinal cord injury in rats.

Cervical spinal cord injury (SCI) impairs arm and hand function largely by interrupting descending tracts. Most SCI spare some axons at the lesion, including the corticospinal tract (CST), which is critical for voluntary movement. We targeted descending motor connections with paired electrical stimulation of motor cortex and cervical spinal cord in the rat. We sought to replicate the previously published effects of intermittent theta burst stimulation of forelimb motor cortex combined with trans-spinal direct current stimulation placed on the skin over the neck to target the cervical enlargement. We hypothesized that paired stimulation would improve performance in skilled walking and food manipulation (IBB) tasks. Rats received a moderate C4 spinal cord contusion injury (200 kDynes), which ablates the main CST. They were randomized to receive paired stimulation for 10 consecutive days starting 11 days after injury, or no stimulation. Behavior was assessed weekly from weeks 4-7 after injury, and then CST axons were traced. Rats with paired cortical and spinal stimulation achieved significantly better forelimb motor function recovery, as measured by fewer stepping errors on the horizontal ladder task (34 ±â€¯9% in stimulation group vs. 51 ±â€¯18% in control, p = .013) and higher scores on the food manipulation task (IBB, 0-9 score; 7.2 ±â€¯0.8 in stimulated rats vs. 5.2 ±â€¯2.6 in controls, p = .025). The effect size for both tasks was large (Cohen's d = 1.0 and 0.92, respectively). The CST axon length in the cervical spinal cord did not differ significantly between the groups, but there was denser and broader ipsilateral axons distribution distal to the spinal cord injury. The large behavioral effect and replication in an independent laboratory validate this approach, which will be trialed in cats before being tested in people using non-invasive methods.