Pulmonary diseases due to mycobacteria cause significant morbidity and mortality to human health. In addition to tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), recent epidemiological studies have shown the emergence of non-tuberculous mycobacteria (NTM) species in causing lung diseases in humans. Although more than 170 NTM species are present in various environmental niches, only a handful, primarily Mycobacterium avium complex and M. abscessus, have been implicated in pulmonary disease. While TB is transmitted through inhalation of aerosol droplets containing Mtb, generated by patients with symptomatic disease, NTM disease is mostly disseminated through aerosols originated from the environment. However, following inhalation, both Mtb and NTM are phagocytosed by alveolar macrophages in the lungs. Subsequently, various immune cells are recruited from the circulation to the site of infection, which leads to granuloma formation. Although the pathophysiology of TB and NTM diseases share several fundamental cellular and molecular events, the host-susceptibility to Mtb and NTM infections are different. Striking differences also exist in the disease presentation between TB and NTM cases. While NTM disease is primarily associated with bronchiectasis, this condition is rarely a predisposing factor for TB. Similarly, in Human Immunodeficiency Virus (HIV)-infected individuals, NTM disease presents as disseminated, extrapulmonary form rather than as a miliary, pulmonary disease, which is seen in Mtb infection. The diagnostic modalities for TB, including molecular diagnosis and drug-susceptibility testing (DST), are more advanced and possess a higher rate of sensitivity and specificity, compared to the tools available for NTM infections. In general, drug-sensitive TB is effectively treated with a standard multi-drug regimen containing well-defined first- and second-line antibiotics. However, the treatment of drug-resistant TB requires the additional, newer class of antibiotics in combination with or without the first and second-line drugs. In contrast, the NTM species display significant heterogeneity in their susceptibility to standard anti-TB drugs. Thus, the treatment for NTM diseases usually involves the use of macrolides and injectable aminoglycosides. Although well-established international guidelines are available, treatment of NTM disease is mostly empirical and not entirely successful. In general, the treatment duration is much longer for NTM diseases, compared to TB, and resection surgery of affected organ(s) is part of treatment for patients with NTM diseases that do not respond to the antibiotics treatment. Here, we discuss the epidemiology, diagnosis, and treatment modalities available for TB and NTM diseases of humans.

中文翻译：

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结核和非结核分枝杆菌感染的流行病学，诊断和治疗的比较分析

由于分枝杆菌引起的肺部疾病对人类健康造成很大的发病率和死亡率。除了由结核分枝杆菌（Mtb）引起的结核病（TB）之外，最近的流行病学研究表明，非结核分枝杆菌（NTM）物种的出现还导致了人类肺部疾病的发生。尽管在各种环境生态环境中存在170多种NTM物种，但只有少数几个主要是鸟分枝杆菌复合物和脓肿分支杆菌与肺部疾病有关。虽然结核病是通过吸入有症状疾病患者产生的含有Mtb的气雾滴传播的，但NTM疾病主要是通过源自环境的气溶胶传播的。但是，吸入后，肺中的肺泡巨噬细胞吞噬了Mtb和NTM。后来，从循环到感染部位会募集各种免疫细胞，从而导致肉芽肿形成。尽管结核病和NTM疾病的病理生理学共有一些基本的细胞和分子事件，但宿主对Mtb和NTM感染的敏感性不同。结核病和非传染性疾病病例之间在疾病表现上也存在惊人的差异。尽管NTM疾病主要与支气管扩张有关，但这种情况很少是结核病的诱发因素。同样，在人类免疫缺陷病毒（HIV）感染的个体中，NTM疾病表现为弥散性肺外形式，而不是粟粒性肺部疾病，这在Mtb感染中可见。结核病的诊断方式，包括分子诊断和药物敏感性测试（DST），与可用于NTM感染的工具相比，它们更先进，并且具有更高的敏感性和特异性。一般而言，对药物敏感的结核病可以通过包含明确定义的一线和二线抗生素的标准多药疗法进行有效治疗。但是，耐药结核病的治疗需要额外的新型抗生素与或不与一线和二线药物联合使用。相反，NTM物种在对标准抗结核药物的敏感性方面表现出明显的异质性。因此，NTM疾病的治疗通常包括使用大环内酯类药物和可注射的氨基糖苷类药物。尽管可以使用公认的国际准则，但是NTM疾病的治疗主要是凭经验而并非完全成功。一般来说，与结核病相比，NTM疾病的治疗持续时间要长得多，并且对不响应抗生素治疗的NTM疾病患者的治疗是受影响器官的切除手术。在这里，我们讨论了人类结核病和NTM疾病的流行病学，诊断和治疗方式。