ABSTRACT
Bacteria are often isolated in stable chronic obstructive pulmonary disease (COPD). Whether fungi are also commonly present and associated with clinical and pathological features of disease is uncertain. We investigated the frequency of filamentous fungal culture and IgE sensitisation to Aspergillus fumigatus and the relationship to clinical outcomes in COPD subjects. COPD subjects were recruited to enter a 1-year observational study. Assessments of lung function, allergen testing and sputum analysis for inflammation, bacteria and fungus were undertaken in COPD subjects and healthy smoking and nonsmoking controls. Filamentous fungi were cultured at baseline in 49% (63 out of 128) of COPD subjects, of which 75% (47 out of 63) were A. fumigatus. Fungus was cultured in three out of 22 controls (two were A. fumigatus). The total sputum cell count and inhaled corticosteroid dosage were significantly increased in COPD patients with a positive filamentous fungal culture at baseline (p<0.05). Sensitisation to A. fumigatus was present in 13% of COPD subjects and was associated with worse lung function (forced expiratory volume in 1 s 39% predicted versus 51% predicted; p=0.01), but not related to filamentous fungal culture. A. fumigatus sensitisation is related to poor lung function. Positive filamentous fungal culture is a common feature of COPD. The clinical significance of this remains uncertain.
Subject(s)
Aspergillosis/microbiology , Aspergillus fumigatus/isolation & purification , Pulmonary Disease, Chronic Obstructive/microbiology , Sputum/microbiology , Adult , Aged , Aspergillosis/complications , Aspergillosis/immunology , Aspergillus fumigatus/immunology , Case-Control Studies , Disease Progression , Female , Forced Expiratory Volume , Humans , Immunoglobulin E/immunology , Male , Middle Aged , Pulmonary Disease, Chronic Obstructive/complications , Pulmonary Disease, Chronic Obstructive/physiopathology , Sputum/cytologyABSTRACT
Colonization of the airways by filamentous fungi can occur in asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis. A recent study found IgE sensitization to Aspergillus fumigatus to be associated with reduced lung function. Significantly higher rates of A. fumigatus were detected in sputum from asthmatics sensitized to this fungus compared to non-sensitized asthmatics. The rate of positive cultures was far higher than equivalent historical samples analysed by the local clinical laboratory following protocols recommended by the UK Health Protection Agency (HPA). This study compares the HPA procedure with our sputum processing method, whereby sputum plugs are separated from saliva and aliquots of approximately 150 mg are inoculated directly onto potato dextrose agar. A total of 55 sputum samples from 41 patients with COPD were analyzed, comparing fungal recovery of five dilutions of sputa on two media. Isolation of A. fumigatus in culture was significantly higher using the research approach compared to the HPA standard method for mycological investigations (P < 0.001). There was also a significant difference in the recovery rate of A. fumigatus (P < 0.05) between media. This highlights the need for a standardized approach to fungal detection which is more sensitive than the method recommended by the HPA.
