Seminars in respiratory and critical care medicine
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Drug-resistant strains of Mycobacterium tuberculosis have emerged as a major threat to global tuberculosis control. Despite the availability of curative antituberculosis therapy for nearly half a century, inappropriate and inadequate treatment has allowed M. tuberculosis to acquire resistance to our most important antituberculosis drugs. The epidemic of drug-resistant tuberculosis has spread quickly in some areas due to the convergence of resistant strains of M. tuberculosis in high-risk patients (e.g., those with human immunodeficiency virus/acquired immunodeficiency syndrome) and high-risk environments (e.g., hospitals and prisons). ⋯ Recently, cases of "totally drug resistant" tuberculosis have been reported. It is estimated that only 10% of all MDR-TB cases are currently receiving therapy and only 2% are receiving quality-assured drugs. This article reviews the management of MDR and XDR-TB and highlights the updated 2011 WHO guidelines on the programmatic management of drug-resistant tuberculosis.
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Semin Respir Crit Care Med · Feb 2013
Review Comparative StudyAdvances in the diagnosis of latent tuberculosis infection.
Accurate diagnosis of tuberculosis (TB) infection is an important component of tuberculosis control programs in many countries. Identification of persons with asymptomatic, or latent, tuberculosis infection allows for treatment of individuals at high risk for progressing to active disease so that the overall burden of tuberculosis disease is diminished. ⋯ Commercially available IGRAs have superior sensitivity and specificity compared with conventional tuberculin skin testingin some settings (particularly bacille-Calmette Guérin-vaccinated individuals). Also discussed are the performance characteristics of these tests in specific populations, including foreign-born persons from high-prevalence countries, close contacts of actively infected patients, immunocompromised populations, and health care workers.
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Latent tuberculosis infection (LTBI) refers to a circumstance in which viable Mycobacterium tuberculosis (MTB) bacilli are present in an individual but symptoms and signs of active disease are lacking, and the bacilli are relatively inactive metabolically. In favorable circumstances, some of these inactive bacilli resume greater metabolic activity and replication, leading to the development of active tuberculosis disease. ⋯ Adverse effects of treatment are considered, as are the special circumstances of human immunodeficiency virus-related LTBI, drug resistance, and use of TLTBI in the context of tumor necrosis factor alpha (TNF-α) inhibition. The review describes the main studies underpinning Centers for Disease Control and Prevention recommendations on use of the new 3-month isoniazid-rifapentine regimen and points to evolving data that may support future modification of those recommendations.
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Semin Respir Crit Care Med · Feb 2013
ReviewThe changing landscape of diagnostic services for tuberculosis.
During the last decade there has been a dramatic change in the laboratory approach to tuberculosis (TB) diagnosis in the developing world. This change began with the realization that acid-fast bacillus smear microscopy alone was totally inadequate to deal with the dual problems of human immunodeficiency virus (HIV)-associated TB and drug-resistant TB that threaten to undermine global progress in TB control. Subsequently, increased financial resources for TB laboratory services and the establishment of a systematic process for endorsement of new TB diagnostic tools and approaches by the World Health Organization (WHO) have led to rapid expansion of TB laboratory services and the availability of several new diagnostic tests that have been introduced. ⋯ The latter methodologies that include line probe assays and an automated cartridge-based real-time polymerase chain reaction (PCR)-based test are being scaled up at an unprecedented pace and are truly revolutionizing the diagnosis of drug-resistant TB. On the other hand, little progress has been made in the quest for a true point-of-care test for TB. Fortunately, this is being addressed in several discovery initiatives that hopefully will provide impetus for the development of rapid, accurate TB diagnostics for the lowest level of the health system.
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Semin Respir Crit Care Med · Feb 2013
ReviewNontuberculous mycobacteria in patients with cystic fibrosis.
As a result of their underlying lung disease, patients with cystic fibrosis (CF) have a higher risk of developing nontuberculous mycobacteria (NTM) infections compared with the general population. Although NTM may be present intermittently in low amounts in the airways of CF patients without an apparent clinical effect, progressive respiratory decline due to NTM disease may also occur. Identifying this latter group of patients can be challenging for clinicians because the usual symptoms exhibited by infected individuals without CF may be difficult to distinguish from the baseline respiratory dysfunction of a patient with CF. ⋯ For CF patients under evaluation for lung transplantation, NTM can play a critical role in determining overall outcomes, and treatment in the pre- and post-transplant period may be vital to success. A general approach to NTM in CF thus involves surveillance to detect NTM, careful monitoring for associated clinical decline, and consideration of treatment given for those with an otherwise unexplained deterioration. In this review, the epidemiology and clinical course of NTM in CF is described with an algorithm for management proposed.