PCR-based detection of Aspergillus fumigatus Cyp51A mutations on bronchoalveolar lavage:a multicentre validation of the AsperGenius assay (R) in 201 patients with haematological disease suspected for invasive aspergillosis

Objectives: In patients with invasive aspergillosis (IA), fungal cultures are mostly negative. Consequently, azole resistance often remains undetected. The AsperGenius (R) multiplex real-time PCR assay identifies clinically relevant Aspergillus species and four resistance-associated mutations (RAMs; TR34/L98H/T289A/Y121F) in the Cyp51A gene. This multicentre study evaluated the diagnostic performance of this assay on bronchoalveolar lavage (BAL) fluid and correlated the presence of RAMs with azole treatment failure and mortality.Methods: Stored BAL samples from patients with haematological diseases with suspected IA were used. BAL samples that were galactomannan/culture positive were considered positive controls for the presence of Aspergillus. Azole treatment failure and 6 week mortality were compared in patients with and without RAMs that had received >= 5 days of voriconazole monotherapy.Results: Two hundred and one patients each contributed one BAL sample, of which 88 were positive controls and 113 were negative controls. The optimal cycle threshold cut-off value for the Aspergillus species PCR was >38. With this cut-off, the PCR was positive in 74/88 positive controls. The sensitivity, specificity, positive predictive value and negative predictive value were 84%, 80%, 76% and 87%, respectively. 32/74 BAL samples were culture negative. Azole treatment failure was observed in 6/8 patients with a RAM compared with 12/45 patients without RAMs (P = 0.01). Six week mortality was 2.7 times higher in patients with RAMs (50.0% versus 18.6%; P = 0.07).Conclusions: The AsperGenius (R) assay had a good diagnostic performance on BAL and differentiated WT from Aspergillus fumigatus with RAMs, including in culture-negative BAL samples. Most importantly, detection of RAMs was associated with azole treatment failure.