Evaluation of PCR for Detection of DNA Specific for Aspergillus Species in Sera of Patients with Various Forms of Pulmonary Aspergillosis

Pulmonary aspergillosis is classified into invasive, saprophytic, and allergic forms. In this study, we evaluated the usefulness of PCR for differentiating between different forms of aspergillosis or in monitoring disease activity during treatment by detecting DNA specific for Aspergillus species in the serum. Nested PCR was used to detect Aspergillus DNA in the sera of 30 patients with various forms of pulmonary aspergillosis. The results were compared with those of latex agglutination tests for detecting galactomannan antigen. We also examined the serial changes in the results of nested PCR during and after treatment of a subgroup of patients with invasive pulmonary aspergillosis with amphotericin B. The highest proportion of positive nested PCR results were in patients with invasive aspergillosis (10 of 12; 83%), while patients with pulmonary aspergilloma had the lowest frequency of positive tests (1 of 9; 11%). These results suggested that the sensitivity of the nested PCR depends on the extent of invasion by Aspergillus species. Serial assays showed that the results of nested PCR became negative shortly after commencement of antifungal treatment and that such changes did not correlate with clinical responsiveness to treatment. Our results indicate the potential usefulness of nested PCR with serum samples for the diagnosis of invasive aspergillosis and the detection of a shift in the status of infection from a noninvasive type to invasive aspergillosis. However, the results of the nested PCR did not correlate with the response to antifungal treatment.Pulmonary aspergillosis is classified into three types: invasive, saprophytic, and allergic. The type of disease caused by Aspergillus species is determined by the host immune activity and structural abnormalities of the bronchi and lung (2, 10, 17). Recently, Gefter et al. (8, 9) proposed a new type of semi-invasive pulmonary aspergillosis as an intermediate form between the invasive and saprophytic types. Binder et al. (3) later described a similar condition as chronic necrotizing pulmonary aspergillosis (CNPA). In spite of this classification, it is often difficult to differentiate among these disease forms, and intermediate or borderline cases often exist (1, 15).In a series of recent studies, we reported the usefulness of nested PCR for the detection of DNA specific for Aspergillus species in serum samples and for the diagnosis of invasive pulmonary aspergillosis (IPA) (11, 22). In the present study, we evaluated the usefulness of nested PCR for differentiating between different forms of pulmonary aspergillosis.