Aspergillus Common in Bronchiectasis Pulmonary Mycobiome, Associated With Exacerbations

The results of study published in the European Respiratory Journal demonstrated that the pulmonary mycobiome is clinically relevant in bronchiectasis and patients should be screened for Aspergillus-associated disease even if they appear to be clinically stable.

Lead author Micheál Mac Aogáin, PhD, from the Lee Kong Chian School of Medicine, Nanyang Technological University in Singapore, and colleagues recruited patients as part of the international multicenter cross-sectional Cohort of Asian and Matched European Bronchiectasis (CAMEB) study. The investigators used targeted amplicon shotgun sequencing of the 18S-28S rRNA internally transcribed spacer regions 1 and 2 to determine the mycobiome in 238 patients with bronchiectasis. Equal numbers of patients from Asia (Singapore and Kuala Lumpur) and Europe (Dundee, Scotland) were recruited to assess the effects of geography on the mycobiome in bronchiectasis. 

The investigators found that the pulmonary mycobiome is distinct in bronchiectasis. Bronchiectasis-associated genera included Aspergillus, Cryptococcus, Clavispora, Botrytis, and Alternaria. Patients from Asia had a significantly higher abundance of Simplicillium, Trichosporon, and Aspergillus, whereas those from Europe had a higher abundance of Wickerhamomyces, Clavispora, and Cryptococcus. Given that Aspergillus is a bronchiectasis-associated fungal genus and that it has a known pathogenic role in other chronic respiratory diseases, the authors further investigated this pathogen.

The data demonstrated that A fumigatus and A terreus are identified in bronchiectasis and associated with exacerbation. The Asian cohort tended to have a greater conidial burden of A fumigatus, while the European cohort had a greater burden of A terreus. A high burden of A terreus, whether alone or in combination with A fumigatus, was associated with significantly more exacerbations.

The investigators detected a high frequency of Aspergillus-associated sensitization and allergic bronchopulmonary aspergillosis. These pathogens were associated with more severe disease, increases in exacerbations, and increased pulmonary dysfunction.

Reference

Mac Aogáin M, Chandrasekaran R, Hou ALY, et al. Immunological corollary of the pulmonary mycobiome in bronchiectasis: the CAMEB study [published online June 7, 2018]. Eur Respir J. doi:10.1183/13993003.00766-2018