Isolation of filamentous fungi from sputum in asthma is associated with reduced post‐bronchodilator FEV₁

Abstract

BackgroundFungal sensitization is common in severe asthma, but the clinical relevance of this and the relationship with airway colonization by fungi remain unclear. The range of fungi that may colonize the airways in asthma is unknown.ObjectiveTo provide a comprehensive analysis on the range of filamentous fungi isolated in sputum from people with asthma and report the relationship with their clinico-immunological features of their disease.MethodsWe recruited 126 subjects with a diagnosis of asthma, 94% with moderate-severe disease, and 18 healthy volunteers. At a single stable visit, subjects underwent spirometry; sputum fungal culture and a sputum cell differential count; skin prick testing to both common aeroallergens and an extended fungal panel; specific IgE to Aspergillus fumigatus. Fungi were identified by morphology and species identity was confirmed by sequencing. Four patients had allergic bronchopulmonary aspergillosis.ResultsForty-eight percent of asthma subjects were IgE-sensitized to one fungal allergen and 22% to ≥ 2. Twenty-seven different taxa of filamentous fungi were isolated from 54% of their sputa, more than one species being detected in 17%. This compared with 3 (17%) healthy controls culturing any fungus (P < 0.01). Aspergillus species were most frequently cultured in isolation followed by Penicillium species. Post-bronchodilator FEV1 (% predicted) in the subjects with asthma was 71(± 25) in those with a positive fungal culture vs. 83 (± 25) in those culture-negative, (P < 0.01).Conclusion and Clinical RelevanceNumerous thermotolerant fungi other than A. fumigatus can be cultured from sputum of people with moderate-to-severe asthma; a positive culture is associated with an impaired post-bronchodilator FEV1, which might be partly responsible for the development of fixed airflow obstruction in asthma. Sensitization to these fungi is also common.

Treatment options in severe fungal asthma and allergic bronchopulmonary aspergillosis

“…As noted previously, the link between fungal sensitisation and severe asthma has been increasingly recognised as a significant piece of the larger asthma puzzle [1][2][3][4][5][6][7][8][9]. Recently this association between fungal sensitisation and the severe asthma phenotype has been further supported by significant correlations between indoor Aspergillus spore air sample concentrations, recovery of fungi (most commonly but not solely A. fumigatus) from respiratory tract cultures and more severe clinical asthma [97,98]. In one recent paediatric study, 59% of children with severe persistent asthma were found to have fungal sensitisation [99].…”

Identifying risk factors for exposure to culturable allergenic moulds in energy efficient homes by using highly specific monoclonal antibodies

“…Aspergillus/Penicillium and Cladosporium were the most frequent fungi identified, 499 which corresponds to other studies (Flannigan et al, 2011 implicated in the initiation or exacerbation of asthma (Agbetile et al, 2012). The 506 identification and control of these high risk fungi may help to improve health and 507 benefit asthmatic individuals , although the complex interaction 508 between occupant behaviours and the built environment must also be considered…”

Allergic fungal airway disease

“…People with moderate to severe asthma who are sensitized to Aspergillus have impaired lung function, as shown by reduced FEV 1 , more severe airway obstruction, and the need for higher corticosteroid doses [99,100]. A 22% reduction in lung function was associated with fungal sensitization and fungus-positive sputum culture in patients with moderate to severe asthma [101]. The majority of recovered fungi were isolates of A fumigatus, although more than 20 other taxa were also detected [101].…”