Leveraging Advances in Tuberculosis Diagnosis and Treatment to Address Nontuberculous Mycobacterial Disease

Ravikiran M. Raju; Sagar M. Raju; Yanlin Zhao; Eric J. Rubin

Disclosures

Emerging Infectious Diseases. 2016;22(3):365-369. 

In This Article

Abstract and Introduction

Abstract

The nontuberculous mycobacteria (NTM), defined as any mycobacterial pathogen other than Mycobacterium tuberculosis or Mycobacterium leprae, are a diverse group of pathogens that collectively cause a substantive but often unappreciated worldwide burden of illness. Although NTMs may cause illness similar to M. tuberculosis, these pathogens generally do not respond to classic tuberculosis (TB) drug regimens, resulting in misdiagnosis and poor treatment, particularly in resource-poor settings. Although a few high-quality epidemiologic surveys have been made on the topic, existing evidence suggests that NTM-associated disease is much more common than previously thought: more common than TB in the industrialized world and likely increasing in prevalence globally. Despite this evidence, these organisms remain markedly understudied, and few international grants support basic science and clinical research. Here we suggest that the considerable efforts in developing new treatments and diagnostics for TB can be harnessed in the fight against NTM-associated illnesses.

Introduction

In recent years, major investments in basic research related to Mycobaterium tuberculosis have culminated in the large-scale rollout of the GeneXpert (Cepheid, Sunnyvale, CA, USA) diagnostic platform, the approval of bedaquiline for treatment of patients with drug-resistant tuberculosis (TB), and a deeper fundamental understanding of how the bacteria causes disease. These advancements stand in stark contrast to the poor understanding of the nontuberculous mycobacteria (NTMs). The NTMs are a group of organisms within the genus Mycobacterium (excluding M. tuberculosis and M. leprae) that cause a spectrum of diseases that include TB-like lung disease; localized infections of the lymphatic system, skin, soft tissue, or bone; and systemic disease.[1] Previous studies have helped uncover NTM prevalence in industrialized countries in which differentiating between TB and NTM infections is much less challenging because of the availability of molecular techniques for detecting and identifying microorganisms. However, recent studies that have been done to examine the NTM burden of illness in industrialized settings have consistently uncovered an unexpectedly large prevalence (Figure).

Figure.

Summary of key studies of the epidemiology of nontuberculous mycobacteria (NTM) disease in countries populated by low- and middle-income residents. TB, tuberculosis; MDR TB, multidrug-resistant tuberculosis.

Major obstacles to adequately addressing NTM disease include the challenges of diagnosis and treatment as well as the lack of active research to understand the pathogenesis of these organisms. In each of these arenas, it is critical that we address gaps in the knowledge and capacity to deal with NTM-associated illness. By increasing funding to programs that seek to expand basic knowledge of NTMs and leveraging advancements in TB diagnostics and therapeutics, we can begin to form a deeper understanding of these pathogens and develop appropriate measures to address them. Here, we outline some of the challenges surrounding the diagnosis and treatment of NTMs and research of these organisms and propose avenues for how the road paved by the fight against TB can serve as a scaffold for advancing our understanding of these related, neglected pathogens.

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