The clinical significance of Aspergillus-positive respiratory samples

Aspergilli moulds are frequently detected in sputum and other respiratory samples. It is not known what the significance of these findings is, or how to differentiate contamination, temporary or persistent colonisation from clinical infection when Aspergilli are found in respiratory samples.

In this study we studied the clinical significance of Aspergillus findings from respiratory samples.

We retrospectively evaluated 299 patients who had provided Aspergillus-positive respiratory samples in 2007-2016, which provided a follow-up time of 3-13 years. Data were collected from laboratory registry and Helsinki University Hospital medical records. Underlying diseases, immunosuppression, reasons for sample collection, clinical significance of positive Aspergillus culture, antifungal medication, and patient survival were assessed.

Underlying pulmonary disease had 88% of patients, most commonly asthma (44%), bronchiectasis (30%) or COPD (21%). Corticosteroids (orally or inhalation therapy) prior to positive samples used 78%; the use of corticosteroids did not explain the development of Aspergillus disease. Pulmonary disease caused by Aspergillus was identified in 88 (29%) of the reviewed patients; remaining samples did not represent clinical disease. Chronic cavitary or fibrosing pulmonary aspergillosis (CCPA or CFPA) had 44 (49%) of the diseased. The probability of Aspergillus disease increased when Aspergillus-positive samples were given repeatedly within 1 year (p = .001). Mortality for all reasons was 45%. The repeated positive samples did not predict survival (p = .084), but the diagnosis of CPA did (p < .001).

The possibility of Aspergillus disease increases when Aspergilli are found repeatedly, collection of samples should be repeated due to method insensitivity. Diagnosis of CPA predicted significantly lower survival.