Evaluation of Three Commercial PCR Assays for the Detection of Azole-Resistant Aspergillus fumigatus from Respiratory Samples of Immunocompromised Patients

This is the first study comparing three commercially available PCR assays for the detection of Aspergillus DNA from respiratory specimen of immunocompromised patients and the presence of cyp51A gene mutations. Bronchoalveolar lavages (BALs, N = 103) from patients with haematological/oncological underlying diseases were retrospectively investigated. The performance of three PCR assays, namely MycoGENIE(R) Aspergillus fumigatus Real-Time PCR Kit (Adamtech), Fungiplex(R) Aspergillus Azole-R IVD Real-Time PCR Kit (Bruker Daltonik GmbH) and AsperGenius(R) (PathoNostics B.V.), were evaluated. All patients were categorised following current EORTC/MSG criteria, with exclusion of the PCR-results. From the 11 invasive pulmonary aspergillosis (IPA) probable samples, eight were detected with MycoGENIE(R), resulting in a sensitivity of 80% and a specificity of 73%. Furthermore, Fungiplex(R) resulted in six positive BALs with a sensitivity of 60% and a specificity of 91% and AsperGenius(R) in seven positive BAL samples, with a sensitivity of 64% and a specificity of 97%. No proven IPA was detected. One isolate showed phenotypically an azole-resistance, which was also detected in each of the tested PCR assays with the mutation in TR34. The here tested PCR assays were capable of reliably detecting A. fumigatus DNA, as well as differentiation of the common cyp51A gene mutations. However, evaluation on the AsperGenius(R) assay revealed a low risk of false positive results.

Automated summary

This study compared three commercially available PCR assays for detecting Aspergillus DNA from respiratory specimens of immunocompromised patients and the presence of cyp51A gene mutations. The tested PCR assays were capable of reliably detecting A. fumigatus DNA and differentiating common cyp51A gene mutations. However, the AsperGenius(R) assay had a low risk of false positive results.