The current American Thoracic Society (ATS)/European Respiratory Society (ERS)/European Society of Clinical Microbiology and Infectious Diseases (ESCMID)/Infectious Diseases Society of America (IDSA) treatment guidelines require a combination of clinical, radiographic, and microbiologic assessments to diagnose NTM pulmonary disease.1
The symptoms of NTM pulmonary disease are variable and nonspecific, which may result in a delayed diagnosis.2,3 Most patients with NTM pulmonary disease have chronic or recurring productive cough.2 Constitutional symptoms may also be present, especially in the setting of more advanced disease.2 Symptoms should be monitored regularly as worsening may indicate disease progression.2,5
Lung radiographs help to establish the initial NTM pulmonary disease diagnosis as well as monitor disease progression over time.
On a high-resolution computed tomography scan, NTM pulmonary disease may be observed as bronchiectasis with multiple small nodules. Nodular or cavitary opacities can be seen on a chest radiograph.2
Images from Dettmer S, et al. J Clin Med. 2021;10(12):2736 under the Creative Commons Attribution License (CC BY).6
Two distinct radiographic presentations of NTM pulmonary disease are typically observed — nodular-bronchiectatic or fibrocavitary — each with their own common patient characteristics.2,5
Nodular-bronchiectatic disease often progresses slowly over many years.
Typical patient characteristics include:
Computed Tomography Scan Showing Lung Nodules
Computed tomography scan reveals multiple lung nodules indicated by the white arrows.
Image from Dettmer S, et al. J Clin Med. 2021;10(12):2736 under the Creative Commons Attribution License (CC BY).6
Fibrocavitary disease may have more rapid disease progression.
Typical patient characteristics include:
Chest Radiograph Showing Multiple Cavities
Chest radiograph shows parenchymal opacity which contains multiple cavities in the right upper lobe. Image is unmodified from Koh WJ, et al. J Korean Med Sci. 2005;20:913 under the Creative Commons Attribution Non-Commercial License (CC BY-NC).7
The isolation of NTM from respiratory clinical samples is essential for the diagnosis of NTM pulmonary disease.2 Once antimycobacterial therapy is initiated, sputum cultures are also followed serially over time as a marker of treatment response.1
Microbiologic findings consistent with NTM pulmonary disease include:
Solid media allow for the observation of colony morphology, growth rates, recognition of mixed mycobacteria infections, and quantitation of the infecting organism.2
Cultures in broth media have a higher yield of mycobacteria and produce more rapid results than those on solid media, but may not be satisfactory on their own because of bacterial overgrowth.2
Example of Colonies on Solid Media
Image is unmodified from Gieger A, et al. Nepal J Ophthalmol. 2017;9(1):91–4 under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License (CC BY-NC-ND).8
