Mycobacterial Diseases
Open Access

The Role of Non-Tuberculosis Mycobacteria in Bronchiectasis

Sinisa Evie^{* *}Correspondence: Sinisa Evie, Department of Clinical Immunology, St James’s University, Leeds, United Kingdom, Email:

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Description

Non-Cystic Fibrosis Bronchiectasis (NCFB) is a chronic respiratory condition characterized by the abnormal and permanent dilation of the bronchi, leading to impaired mucociliary clearance and recurrent lung infections. Among the various pathogens that can infect patients with NCFB, Non- Tuberculous Mycobacteria (NTM) are increasingly recognized as significant contributors to morbidity. NTM are a diverse group of mycobacteria, distinct from Mycobacterium tuberculosis and Mycobacterium leprae that can cause pulmonary disease, especially in individuals with underlying lung conditions like NCFB. NTM are environmental bacteria found in soil, water, and dust. They are typically not pathogenic to healthy indi=iduals but can cause serious infections in those with compromised lung function or immune systems. NTM infections are notoriously difficult to diagnose and treat due to their variable clinical presentations and intrinsic resistance to many antibiotics.

Prevalence of NTM in NCFB patients

Studies have shown that NTM infections are common among patients with NCFB. The prevalence rates vary geographically, with higher rates reported in regions with humid climates. In NCFB patients, NTM colonization and infection can exacerbate lung damage, leading to a decline in lung function, increased frequency of exacerbations, and a poorer quality of life. The most common NTM species associated with NCFB include Mycobacterium Avium Complex (MAC), Mycobacterium abscessus, and Mycobacterium kansasii. MAC is particularly prevalent and is known for causing chronic pulmonary disease that mimics tuberculosis but is more indolent in nature.

Pathogenesis and clinical manifestations

The pathogenesis of NTM disease in NCFB involves the colonization of damaged bronchi and impaired mucociliary clearance mechanisms. This leads to the formation of biofilms and persistent infection, which can further deteriorate lung function. NTM infections present a spectrum of clinical manifestations, ranging from asymptomatic colonization to severe, progressive lung disease. Common symptoms include chronic cough, sputum production, hemoptysis, fatigue, and weight loss. These symptoms are often indistinguishable from those of NCFB itself, complicating the diagnosis. Diagnosing NTM infections in NCFB patients is challenging due to the nonspecific nature of symptoms and the need to distinguish between mere colonization and active infection. The American Thoracic Society (ATS) and Infectious Diseases Society of America (IDSA) have established criteria for the diagnosis of NTM pulmonary disease, which include clinical, radiographic, and microbiological components.

A definitive diagnosis typically requires:

Clinical criteria: Symptoms such as chronic cough, sputum production, and radiological evidence of bronchiectasis or nodular opacities.

Microbiological criteria: Positive cultures from sputum or bronchial washings, usually requiring two positive sputum cultures or one positive culture from bronchoscopic specimens.

Treatment and management

Managing NTM infections in NCFB patients is complex and requires a multifaceted approach. The primary goals of treatment are to eradicate the infection, reduce symptoms, and prevent further lung damage. Treatment regimens often include multiple antibiotics over extended periods, typically 12 months or longer after culture conversion. The choice of antibiotics depends on the NTM species and its drug susceptibility profile. Commonly used antibiotics for MAC infections include macrolides ethambutol, and rifamycins. For Mycobacterium abscessus, treatment is more challenging due to its extensive antibiotic resistance, often requiring combinations of macrolides, amikacin, and other agents like tigecycline or clofazimine. Given the complexity of NTM disease management, a multidisciplinary approach is essential. This includes collaboration between pulmonologists, infectious disease specialists, microbiologists, and pharmacists to optimize treatment plans and monitor for adverse effects. Regular followups and monitoring of treatment response through sputum cultures and radiographic imaging are important.

Conclusion

Non-tuberculous mycobacterial disease is a common and significant complication in patients with non-cystic fibrosis bronchiectasis. Its presence can exacerbate lung damage and complicate the clinical management of NCFB. Early recognition, accurate diagnosis, and appropriate treatment are critical to improving patient outcomes. Continued research and awareness are necessary to better understand the epidemiology, pathogenesis, and optimal management strategies for NTM infections in this vulnerable patient population.