Gap between non-tuberculous mycobacteria testing behaviour and guidelines identified

A study published in BMJ Open Respiratory Research has revealed that, contrary to guideline recommendations, 68% of clinicians managing bronchiectasis patients do not test them for non-tuberculous mycobacteria (NTM) infection prior to starting macrolide treatment.

The study (Wagner D, van Ingen J, van der Laan R et al. Non- tuberculous mycobacterial lung disease in patients with bronchiectasis: perceived risk, severity and guideline adherence in a European physician survey. BMJ Open Resp Res 2020; 7: e000498. doi:10.1136/bmjresp2019-000498) showed that this is despite the high awareness of the increased risk of NTM lung disease (NTM-LD) and its associated morbidity and mortality in bronchiectasis patients. Guidelines recommend NTM testing as NTM isolation prevalence in bronchiectasis patients ranges from 2% to 63%. 

Long-term macrolide treatment is often used to prevent exacerbations in patients with bronchiectasis. However, single macrolide therapy should not be initiated until the presence of NTM infection has been excluded, due to the potential development of macrolide-resistant bacteria, which could lead to worse longer-term outcomes for patients.

The European Respiratory Society (ERS) bronchiectasis guidelines therefore recommend testing for NTM culture positivity before starting macrolide monotherapy. The authors of this study concluded that, despite most respondents stating that they follow ERS guidelines, all aspects of these recommendations do not appear to be put into place. 

This is the first study to investigate physicians’ perception of the risk of NTM-LD in patients with bronchiectasis and its impact on testing practices. The researchers surveyed 280 physicians who manage bronchiectasis patients in five European countries, including the UK, to understand how they perceive the risk of NTM infections in bronchiectasis patients and how they monitor these patients for NTM infection. 

Of the surveyed physicians, 85% tested at least some of their bronchiectasis patients for NTM, with approximately half testing all of their patients with bronchiectasis at initial presentation or diagnosis. Of those testing for NTM, only 38% said they tested prior to initiating macrolide monotherapy. However, in the UK this number was significantly higher, with 66% of those who test for NTM do so before starting patients on macrolide treatment.

N-on-tuberculous mycobacteria are ubiquitous environmental bacteria responsible for the development of NTM-LD. These infections are a growing problem, with the overall incidence of isolations having increased almost 10-fold since 1995. The symptoms are usually non-specific and include chronic cough, shortness of breath, tiredness, fever and weight loss.

The term bronchiectasis designates an irreversible dilation of the bronchi and bronchioles as a result of destruction of pulmonary muscle or connective tissue. This pathological widening of the airways limits mucociliary clearance and makes the lungs more susceptible to infection, due to increased accumulation of mucus. The inflammatory reaction ultimately leads to a thickening and thus an inflexibility of the walls of the airways, which encourages further accumulation of mucus.