Symposium 12

Abstract:
The assessment of sputum mycobacterial culture is crucial for diagnosing, evaluating the clinical course, and assessing treatment responses in patients with nontuberculous mycobacterial lung disease (NTM-LD). It is important to note that a positive NTM culture in a respiratory specimen does not definitively indicate a pulmonary infection. Potential factors, such as NTM specimen contamination or colonization of the respiratory tract by NTM must be meticulously considered. Hence, the current recommended diagnostic procedure for NTM-LD involves the collection of three sputum samples on separate days, coupled with a thorough evaluation of clinical and radiological findings. Nevertheless, determining the clinical status of NTM in sputum culture remains a clinical challenge.

In addition to its role in NTM diagnosis, the culture of serial sputum samples serves as a vital biomarker for monitoring the clinical course and treatment response. Microbiological persistence in NTM-LD patients is associated with disease progression. Regarding treatment outcomes, achieving microbiological cure at the completion of treatment is linked to longer survival. Furthermore, early changes in semiquantitative colony counts in sputum culture predict clinical and radiological improvement, indicating treatment success. Despite this compelling evidence, a notable limitation is that some NTM-LD patients may not produce adequate sputum for evaluation.

In this section, I will address the challenges in interpreting sputum culture in NTM-LD and try to provide insights into potential future directions.