Does ERS Recommend Sputum Fungal Culture for Bronchiectasis Etiologic Workup?
No, the European Respiratory Society (ERS) does not include sputum fungal culture in the minimum bundle of etiological tests for bronchiectasis. The 2017 ERS guidelines specifically recommend only three core tests: differential blood count, serum immunoglobulins (IgG, IgA, IgM), and testing for allergic bronchopulmonary aspergillosis (ABPA), with sputum culture mentioned only for bacterial monitoring purposes 1.
ERS Minimum Etiological Testing Bundle
The ERS guidelines explicitly state the minimum bundle as a conditional recommendation with very low quality evidence 1:
- Differential blood count - to identify lymphopenia, neutropenia suggesting immune deficiency, or lymphocytosis suggesting haematological malignancy 1
- Serum immunoglobulins (total IgG, IgA, IgM) - to detect common variable immune deficiency, present in 2-8% of bronchiectasis patients, which is modifiable with immunoglobulin replacement 1
- Testing for ABPA - because establishing this diagnosis alters management 1
Sputum Culture Recommendations
The ERS guidelines state that sputum culture is expected to be undertaken for monitoring purposes of bacterial infection, not as part of the etiological workup 1. The 2025 ERS guidelines similarly recommend initial diagnostic workup should include sputum culture for bacteria, mycobacteria, and fungi, but this appears in the context of comprehensive management rather than the minimum etiological bundle 2.
Mycobacterial culture is mentioned as potentially helpful only in selected cases where non-tuberculous mycobacteria (NTM) are suspected as an aetiological cause 1.
Clinical Context for Fungal Testing
Fungal culture becomes relevant in specific clinical scenarios rather than routine etiological workup:
- When ABPA is suspected based on screening tests (which is part of the minimum bundle) 1
- When clinical features suggest fungal disease 1
- In patients with severe or rapidly progressive disease where additional tests beyond the minimum bundle are appropriate 1
Research demonstrates that ITS2 sequencing greatly increases detection of fungi from sputum compared to culture, with different fungal profiles in CF versus non-CF bronchiectasis 3. However, this research finding has not translated into guideline recommendations for routine fungal culture in etiological workup.
Important Caveats
The ERS acknowledges that no publications directly addressed whether routine aetiological investigation protocols provide benefit compared to clinically driven investigations 1. The recommendation for the minimum bundle is based on very low quality evidence, with only observational studies showing that 7-37% of patients had management changes following aetiological investigation 1.
Additional tests beyond the minimum bundle may be appropriate when specific clinical features suggest particular etiologies, but fungal culture is not part of the standardized initial etiological workup 1.