Christopher Gilpin

WHO's new end TB strategy.

On May 19, 2014, the 67th World Health Assembly (WHA) adopted WHO’s “Global strategy and targets for tuberculosis prevention, care and control after 2015”. This post-2015 global tuberculosis strategy, labelled the End TB Strategy, was shaped during the past 2 years. A wide range of stakeholders—from ministries of health and national tuberculosis programmes to technical and scientifi c institutions, fi nancial and development partners, civil society and health activists, non-governmental organisations, and the private sector—contributed to its development. The strategy has a vision of making the world free of tuberculosis, with zero deaths, disease, and suff ering due to the disease (see appendix p 1 for summary of the End TB Strategy). In 2013, 9 million people fell ill with tuberculosis and 1·5 million died; about a quarter of them were HIV positive. Poor and deprived groups also bore the brunt of the enormous socioeconomic burden imposed by the disease and deaths. Concerned by this persistent human suff ering due to tuberculosis, but encouraged by the progress achieved during the past two decades and recognising the need to mount a multisectoral response to eff ectively address the problem, the health ministers at the WHA approved WHO’s proposal to push the limit of ambition to “end the global tuberculosis epidemic” by 2035, marked by well defi ned milestones and targets set along the way. Ending the tuberculosis epidemic implies bringing the levels of tuberculosis in the whole world down to converge with those already attained by many rich countries: fewer than ten new tuberculosis cases occurring per 100 000 population per year amounting to 90% reduction in tuberculosis incidence and tuberculosis deaths reduced by 95%. The rich countries achieved remarkable reductions in the tuberculosis burden not only by delivering adequate tuberculosis services, but also by pursuing universal access to health care and social protection while rapidly improving nutrition and economic conditions. Ending the tuberculosis epidemic in high-incidence countries needs a similar approach that guarantees access to high-quality tuberculosis care and prevention to all while simul taneously addressing the social determinants of tuberculosis. To this eff ect, elimination of catastrophic costs that tuberculosis-aff ected families face is an important milestone to be achieved under the End TB Strategy well within the next decade. Importantly, though, achievement of universal access to currently available methods of tuberculosis care and prevention will not be enough to end the epidemic within two decades. Global investments and eff orts are also essential to develop improved methods to diagnose, treat, and prevent tuberculosis. Equal emphasis on achievement of universal access to tuberculosis care and prevention, addressing of weaknesses in health systems and social determinants of tuberculosis, and pursuing of research and innovation for improved approaches and strategies constitute the core of the End TB Strategy. The achievements of the past two decades provide the basis for further progress. The DOTS (directly observed treatment, short-course) strategy of 1995 expanded access to high-quality tuberculosis care. The Stop TB Strategy of 2006 widened its scope to address management of all forms of tuberculosis including HIV-associated and drug-resistant tuberculosis, through engagement of communities, involvement of all care providers, strengthening of health systems, and fostering of research. Subsequently, the tuberculosis-related Millennium Development Goal to “halt and begin to reverse the incidence of tuberculosis” was achieved; 37 million lives were saved between 2000 and 2013; and a new rapid molecular test to simultaneously diagnose tuberculosis and rifampicin resistance was developed and two novel drugs were introduced. These achievements notwithstanding, the enormity of the task ahead cannot be overemphasised. Overall, the current 2% annual reduction in the global tuberculosis incidence is too slow to achieve an end to the epidemic in the foreseeable future. Tuberculosis remains a top infectious killer of men and women. A third of estimated incident tuberculosis cases go un-notifi ed or undiagnosed and close to half a million multidrug-resistant cases emerge each year. HIV-associated tuberculosis aff ects more than a million people a year. An estimated 2 billion people with latent tuberculosis infection form a reservoir that sustains the global epidemic. Analyses of constraints to global tuberculosis control bring four major persisting barriers to the fore. First, weak health systems including the unregulated non-state sector prevent reaching the currently available methods of diagnosis and treatment to all sections of the populations and a lack of universal health coverage and social protection inhibit provision of comprehensive tuberculosis care and prevention without further impoverishment to those who need it most. Second, determinants such as poverty, under nutrition, migration, and ageing populations enhance vulnerability and maintain the cycle of infection and disease. The risk of tuberculosis is further enhanced by non-communicable health problems such as diabetes, harmful use of alcohol, and tobacco smoking. Third, the lack of optimum methods—a point-of-care test for rapid diagnosis of disease and latent infection; better and safer drug regimens to shorten treatment; and a vaccine to prevent Lancet 2015; 385: 1799–801

Population-based resistance of Mycobacterium tuberculosis isolates to pyrazinamide and fluoroquinolones: results from a multicountry surveillance project

Summary Background Pyrazinamide and fluoroquinolones are essential antituberculosis drugs in new rifampicin-sparing regimens. However, little information about the extent of resistance to these drugs at the population level is available. Methods In a molecular epidemiology analysis, we used population-based surveys from Azerbaijan, Bangladesh, Belarus, Pakistan, and South Africa to investigate resistance to pyrazinamide and fluoroquinolones among patients with tuberculosis. Resistance to pyrazinamide was assessed by gene sequencing with the detection of resistance-conferring mutations in the pncA gene, and susceptibility testing to fluoroquinolones was conducted using the MGIT system. Findings Pyrazinamide resistance was assessed in 4972 patients. Levels of resistance varied substantially in the surveyed settings (3·0–42·1%). In all settings, pyrazinamide resistance was significantly associated with rifampicin resistance. Among 5015 patients who underwent susceptibility testing to fluoroquinolones, proportions of resistance ranged from 1·0–16·6% for ofloxacin, to 0·5–12·4% for levofloxacin, and 0·9–14·6% for moxifloxacin when tested at 0·5 μg/mL. High levels of ofloxacin resistance were detected in Pakistan. Resistance to moxifloxacin and gatifloxacin when tested at 2 μg/mL was low in all countries. Interpretation Although pyrazinamide resistance was significantly associated with rifampicin resistance, this drug may still be effective in 19–63% of patients with rifampicin-resistant tuberculosis. Even though the high level of resistance to ofloxacin found in Pakistan is worrisome because it might be the expression of extensive and unregulated use of fluoroquinolones in some parts of Asia, the negligible levels of resistance to fourth-generation fluoroquinolones documented in all survey sites is an encouraging finding. Rational use of this class of antibiotics should therefore be ensured to preserve its effectiveness. Funding Bill & Melinda Gates Foundation, United States Agency for International Development, Global Alliance for Tuberculosis Drug Development.

A standardised method for interpreting the association between mutations and phenotypic drug resistance in Mycobacterium tuberculosis

A clear understanding of the genetic basis of antibiotic resistance in Mycobacterium tuberculosis is required to accelerate the development of rapid drug susceptibility testing methods based on genetic sequence. Raw genotype–phenotype correlation data were extracted as part of a comprehensive systematic review to develop a standardised analytical approach for interpreting resistance associated mutations for rifampicin, isoniazid, ofloxacin/levofloxacin, moxifloxacin, amikacin, kanamycin, capreomycin, streptomycin, ethionamide/prothionamide and pyrazinamide. Mutation frequencies in resistant and susceptible isolates were calculated, together with novel statistical measures to classify mutations as high, moderate, minimal or indeterminate confidence for predicting resistance. We identified 286 confidence-graded mutations associated with resistance. Compared to phenotypic methods, sensitivity (95% CI) for rifampicin was 90.3% (89.6–90.9%), while for isoniazid it was 78.2% (77.4–79.0%) and their specificities were 96.3% (95.7–96.8%) and 94.4% (93.1–95.5%), respectively. For second-line drugs, sensitivity varied from 67.4% (64.1–70.6%) for capreomycin to 88.2% (85.1–90.9%) for moxifloxacin, with specificity ranging from 90.0% (87.1–92.5%) for moxifloxacin to 99.5% (99.0–99.8%) for amikacin. This study provides a standardised and comprehensive approach for the interpretation of mutations as predictors of M. tuberculosis drug-resistant phenotypes. These data have implications for the clinical interpretation of molecular diagnostics and next-generation sequencing as well as efficient individualised therapy for patients with drug-resistant tuberculosis. A comprehensive basis for interpreting mutations to predict antibiotic resistance in tuberculosis http://ow.ly/hhwJ30g9jCY

Genetic sequencing for surveillance of drug resistance in tuberculosis in highly endemic countries: a multi-country population-based surveillance study

Summary Background In many countries, regular monitoring of the emergence of resistance to anti-tuberculosis drugs is hampered by the limitations of phenotypic testing for drug susceptibility. We therefore evaluated the use of genetic sequencing for surveillance of drug resistance in tuberculosis. Methods Population-level surveys were done in hospitals and clinics in seven countries (Azerbaijan, Bangladesh, Belarus, Pakistan, Philippines, South Africa, and Ukraine) to evaluate the use of genetic sequencing to estimate the resistance of Mycobacterium tuberculosis isolates to rifampicin, isoniazid, ofloxacin, moxifloxacin, pyrazinamide, kanamycin, amikacin, and capreomycin. For each drug, we assessed the accuracy of genetic sequencing by a comparison of the adjusted prevalence of resistance, measured by genetic sequencing, with the true prevalence of resistance, determined by phenotypic testing. Findings Isolates were taken from 7094 patients with tuberculosis who were enrolled in the study between November, 2009, and May, 2014. In all tuberculosis cases, the overall pooled sensitivity values for predicting resistance by genetic sequencing were 91% (95% CI 87–94) for rpoB (rifampicin resistance), 86% (74–93) for katG, inhA, and fabG promoter combined (isoniazid resistance), 54% (39–68) for pncA (pyrazinamide resistance), 85% (77–91) for gyrA and gyrB combined (ofloxacin resistance), and 88% (81–92) for gyrA and gyrB combined (moxifloxacin resistance). For nearly all drugs and in most settings, there was a large overlap in the estimated prevalence of drug resistance by genetic sequencing and the estimated prevalence by phenotypic testing. Interpretation Genetic sequencing can be a valuable tool for surveillance of drug resistance, providing new opportunities to monitor drug resistance in tuberculosis in resource-poor countries. Before its widespread adoption for surveillance purposes, there is a need to standardise DNA extraction methods, recording and reporting nomenclature, and data interpretation. Funding Bill & Melinda Gates Foundation, United States Agency for International Development, Global Alliance for Tuberculosis Drug Development.

Diagnosis of opportunistic infections: HIV co-infections - tuberculosis.

Purpose of review Tuberculosis (TB) incidence has declined ∼1.5% annually since 2000, but continued to affect 10.4 million individuals in 2015, with 1/3 remaining undiagnosed or underreported. The diagnosis of TB among those co-infected with HIV is challenging as TB remains the leading cause of death in such individuals. Accurate and rapid diagnosis of active TB will avert mortality in both adults and children, reduce transmission, and assist in timeous decisions for antiretroviral therapy initiation. This review describes advances in diagnosing TB, especially among HIV co-infected individuals, highlights national programs uptake, and impact on patient care. Recent findings The TB diagnostic landscape has been transformed over the last 5 years. Molecular diagnostics such as Xpert MTB/RIF, which simultaneously detects Mycobacterium tuberculosis (MTB) resistance to rifampicin, has revolutionized TB control programs. WHO endorsed the use of Xpert MTB/RIF in 2010 for use in HIV/TB co-infected patients, and later in 2013 for use as the initial diagnostic test for all adults and children with signs and symptoms of pulmonary TB. Line probe assays (LPAs) are recommended for the detection of rifampicin and isoniazid resistance in sputum smear-positive specimens and mycobacterial cultures. A second-line line probe assay has been recommended for the diagnosis of extensively drug-resistant (XDR)-TB Assays such as the urine lateral flow (LF)-lipoarabinomannan (LAM), can be used at the point of care (POC) and have a niche role to supplement the diagnosis of TB in seriously ill HIV-infected, hospitalized patients with low CD4 cell counts of less than 100 cells/&mgr;l. Polyvalent platforms such as the m2000 (Abbott Molecular) and GeneXpert (Cepheid) offer potential for integration of HIV and TB testing services. While the Research and Development (R&D) pipeline appears to be rich at first glance, there are actually few leads for true POC tests that would allow for earlier TB diagnosis or rapid, comprehensive drug susceptibility testing, especially when considering the very high attrition rates observed between biomarker discovery and product market entry. Summary In this review, we describe diagnostic strategies specifically for HIV and TB co-infected individuals. Molecular diagnostics in particular within the past 5 years have revolutionized and ‘disrupted’ this field. They lend themselves to integration of services with platforms capable of polyvalent testing. Impact on patient care is, however, still debatable. What has been highlighted is the need for health system strengthening and for true POC testing that can be used in active case finding.

Current tools available for the diagnosis of drug-resistant tuberculosis

Drug-resistant tuberculosis (DR-TB) poses a major threat to control of tuberculosis worldwide. Diagnosis and treatment of DR-TB are considerably more difficult than for drug-susceptible tuberculosis (TB) and require higher level infrastructure and proficiency from laboratory specialists and clinicians. The World Health Organization (WHO) End TB Strategy calls for early diagnosis and initiation of appropriate treatment of all persons of all ages with any form of drug-susceptible TB or DR-TB. This requires ensuring access to WHO-recommended rapid diagnostics and universal drug susceptibility testing (DST) for all persons with signs and symptoms of TB. There are a number of laboratory tools available for diagnosis of DR-TB, including phenotypic culture-based DST as well as molecular methods. Optimal and complementary use of the available diagnostic tools at the different levels of the tiered network of TB laboratories, as well as correct interpretation of the diagnostic results provided by them is critical for accurate and timely diagnosis of DR-TB thus enabling effective treatment and care of patients.

Implementation of HIV and Tuberculosis Diagnostics: The Importance of Context.

BACKGROUND Novel diagnostics have been widely applied across human immunodeficiency virus (HIV) and tuberculosis prevention and treatment programs. To achieve the greatest impact, HIV and tuberculosis diagnostic programs must carefully plan and implement within the context of a specific healthcare system and the laboratory capacity. METHODS A workshop was convened in Cape Town in September 2014. Participants included experts from laboratory and clinical practices, officials from ministries of health, and representatives from industry. RESULTS The article summarizes best practices, challenges, and lessons learned from implementation experiences across sub-Saharan Africa for (1) building laboratory programs within the context of a healthcare system; (2) utilizing experience of clinicians and healthcare partners in planning and implementing the right diagnostic; and (3) evaluating the effects of new diagnostics on the healthcare system and on patient health outcomes. CONCLUSIONS The successful implementation of HIV and tuberculosis diagnostics in resource-limited settings relies on careful consideration of each specific context.

Global laboratory initiative tool for a stepwise process towards tuberculosis laboratory accreditation.

made with this new test in detecting tuberculosis among patients excreting few bacilli and in identifying rifampicin resistance. For the reasons outlined above and in our article, sputum smear microscopy must be retained as a routine test at peripheral level in low-income countries, at least for the time being. We wish to emphasise the need for good operational research before recommending any replacement of smear microscopy. The old cloth must not be discarded without due assurance that the new cloth is affordable, durable and resistant to stormy weather!

A Risk Assessment-based Approach to Defining Minimum Biosafety Precautions for Tuberculosis Laboratories in Resource-limited Settings

In developing minimum biosafety precautions for laboratories that conduct diagnostic testing for tuberculosis (TB), a risk assessment-based approach was used to define minimum precautions for individual procedures and processes. A consensus-building approach involving three expert committees was necessary because risk assessment is a subjective process with judgments based sometimes on incomplete information. This article describes the process behind the development of recommendations for minimum biosafety precautions for TB laboratories in high-burden and low-resource settings. The recommendations of the expert committees are being used by the World Health Organization (WHO) to produce a safety manual for TB laboratories that is tentatively scheduled for publication in mid-2012. The intended audience for these recommendations is directors and managers of laboratories and programs that conduct testing for TB in resource-limited and high-burden settings. However, the process used here and the recommendations developed are suitable for consideration by all laboratories that conduct testing for TB.

The World Health Organization standards for tuberculosis care and management

Tuberculosis (TB) is a global public health priority, with 10.4 million people developing the disease in 2016 (10% among HIV co-infected individuals), 1.67 million deaths and 490 000 multidrug-resistant (MDR) plus an additional 110 000 rifampicin-resistant cases [1]. The WHO TB Compendium facilitates the delivery of high-quality care to all persons affected by TB http://ow.ly/VzsM30iO8sO