Health Impact of Non-Tuberculous Mycobacteria Pulmonary Disease (NTM-PD)

Nontuberculous mycobacteria are environmental organisms primarily found in soil and water, including locations such as lakes, rivers, agricultural zones, and some industrial sites. Environmental changes facilitate the transport of these organisms to many different settings, including external and internal living spaces. NTM are separate from the Mycobacterium tuberculosis complex (the cause of tuberculosis) and are not the mycobacteria that cause leprosy. With around 200 species, these organisms can be classified into slow growing mycobacteria (SGM ≥ 7 days) or rapid growing mycobacteria (RGM < 7 days), based on their growth rate in solid culture medium. M. avium, M. kansasii, M. xenopi, and M. abscessus are the most common NTM species that can cause pulmonary disease. Unlike M. tuberculosis these mycobacteria are not pathogens, but in the right setting, they can infect humans and produce clinical disease. This is most often seen in people with pre-existing lung damage due to bronchiectasis, chronic obstructive pulmonary disease (COPD), or cystic fibrosis, and NTM infection results in worsening health, and the development of a chronic respiratory illness, NTM-PD.

This study is designed to explore the impact of non-tuberculous mycobacteria-pulmonary disease (NTM-PD) on patients' health, to explore what symptoms are of most concern to people with NTM-PD and to better characterise what non-pharmacological interventions might help this patient group.

The study questions guiding this research are:

• What are the key clinical differences between people living with NTM pulmonary disease and people with bronchiectasis?
• What symptoms are of most importance to people with NTM-PD and is this different to people with bronchiectasis?
• Does the need for non-pharmacological intervention differ for people with NTM-PD compared to other patients with bronchiectasis without NTM-PD? This will be done by comparing the symptoms, investigation results and physiological measurement of people with NTM-PD to a group at risk of NTM-PD but without either NTM infection or disease, namely people with bronchiectasis but no evidence for NTM pulmonary infection. By identifying and analysing any differences between these groups, the study aims to increase the understanding of NTM-PD and so contribute to the development of more effective and evidence-based clinical practice.

This will be accomplished by integrating validated Patient-Reported Outcome Measures (PROMs) with radiological evaluation and respiratory assessments. Additionally, a self-reported questionnaire will be used to rank the most significant symptoms associated with NTM-PD, as well as the daily living activities affected, from the patients' perspective.

The findings could reveal key differences in clinical features and symptoms between these groups, helping to optimise non-pharmacological interventions, improve treatment plans for people with NTM-PD, and highlight areas for future research.

Inclusion criteria

• Age: 18 years or older, able to provide informed consent.

NTM-PD Group:

• Participants will be adults diagnosed with confirmed NTM-PD based on the British Thoracic Society (BTS) guidelines.
• The participant should not be on any antimicrobial therapy (at least two weeks before participation) and should not have previously received or be currently on antimicrobial therapy for NTM-PD.

• BTS guidelines:
• Clinical (both required):
• Pulmonary symptoms, nodular or cavitary opacities on chest radiograph, or a high-resolution CT scan that shows multifocal bronchiectasis with multiple small nodules.
• Appropriate exclusion of other diagnoses.
• Microbiological:
• A minimum of two positive expectorated sputum culture results of the same NTM species from samples collected on separate days within 12 months before recruitment.

OR

• Positive culture results from at least one bronchial wash or lavage. OR
• Transbronchial or other lung biopsy with mycobacterial histopathological features (granulomatous inflammation or AFB) and positive culture for NTM or biopsy showing mycobacterial histopathological features (granulomatous inflammation or AFB) and one or more sputum or bronchial washings that are culture-positive for NTM.

Bronchiectasis Group:

• Diagnosed with bronchiectasis, as confirmed in medical records based on clinical assessment, and radiological findings.
• Never had a history of positive culture result for NTM pulmonary infection.
• The latest NTM-negative result must be within the past 12 months from the study's start date or no earlier than 2024.

Exclusion criteria

• Age: Under 18 years of age, or unable to provide informed consent.

NTM-PD Group:

• No confirmation of NTM-PD diagnosis.
• Diagnosed with a reinfection of NTM-PD.
• Started antimicrobial therapy for NTM-PD.

Bronchiectasis Group:

• No diagnosis of bronchiectasis or diagnosis of bronchiectasis with NTM-PD.
• Diagnosed with other chronic respiratory diseases considered primary conditions, rather than bronchiectasis.
• Participants with a history of NTM pulmonary infection.
• NTM-negative results obtained before 2024.