In patients with endobronchial plaques or pulmonary infiltrates, a positive BAL GM or culture of a tracheal aspirate is considered mycological evidence that supports a probable IAPA diagnosis. In patients with bacterial pneumonia where Aspergillus is cultured only from a sputum sample, there may be a risk of overdiagnosis and thus over-treatment. For clinical practice, clinicians should take into account that a positive culture of an upper airway sample may indicate IAPA, but that confirmation with serum or BAL GM or BAL culture should be pursued. However, one problem is that the background incidence varies in different regions, making it difficult to develop generalized guidelines that apply uniformly. The significance of a positive sputum culture thus depends on the background incidence in a specific unit. Although any Aspergillus-positive respiratory sample is in itself insufficient to classify patients as probable IAPA, a new pulmonary cavitating infiltrate is indicative of IAPA in patients who meet the entry criterion. Therefore, any Aspergillus-positive respiratory sample is sufficient evidence to classify patients as probable IAPA provided that a pulmonary cavitating infiltrate is present (Table 1; Fig. 1).
Fig. 1 Flowchart of probable IAPA classification. (*)If hyphae consistent with Aspergillus are documented in a biopsy of an airway lesion AND Aspergillus is grown from sputum or a tracheal aspirate, the case fulfills the definition of proven IAPA