Identifying Underlying Causes of Bronchiectasis

Your physician needs to send cultures not only for routine respiratory bacteria but also for nontuberculous mycobacteria (NTM) and fungi. ​

Routine cultures alone may overlook significant contributors to ongoing inflammation, airway damage, and recurrent infections.

​Many people assume that a “negative sputum” means everything has been checked, when in fact only standard bacteria were tested. Without additional orders, the lab will not automatically screen for NTM or fungi.

One important example is allergic bronchopulmonary aspergillosis (ABPA). ABPA is a known cause of bronchiectasis and can worsen existing disease by driving chronic airway inflammation. It is more commonly recognized in countries such as India and in certain parts of Europe, yet many patients in the United States go undiagnosed for years. This often happens simply because the appropriate tests are not being ordered. Unless a clinician specifically requests Aspergillus-related testing, neither blood work nor fungal sputum cultures will be performed.

A thorough evaluation for ABPA and other fungal-related contributors should include several key components:

• Blood tests for Aspergillus-specific IgE and IgG, which indicate whether the immune system is reacting strongly to Aspergillus.

• Total IgE levels, which are often significantly elevated in ABPA.

• A complete blood count to assess eosinophils, a type of immune cell that rises in allergic or inflammatory airway conditions.

• Sputum cultures for fungal organisms, including Aspergillus species, to determine whether fungi are present in the airways.

• Chest imaging, especially high-resolution CT scans, which can show patterns characteristic of ABPA such as central bronchiectasis or mucus impaction.

Taken together, these steps provide a much clearer picture of the underlying causes of a person’s bronchiectasis. Identifying ABPA, NTM, or fungal infections early can prevent worsening airway damage and allow for more targeted treatment. For many patients, this broader testing is the missing piece in understanding why their symptoms persist despite standard treatments.

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