Improving the diagnosis of invasive aspergillosis by the detection of Aspergillus in broncho-alveolar lavage fluid: Comparison of non-culture-based assays.

OBJECTIVES: This study aimed to evaluate new tools to diagnose invasive aspergillosis (IA) directly from broncho-alveolar lavage (BAL) samples.

METHODS: All consecutive patients with suspected IA who underwent bronchoscopy with BAL were prospectively included. Mycological culture and ELISA detection of galactomannan (GM) were performed on BAL. Two in-house and two marketed PCR assays were used on BAL DNA extracts to detect Aspergillus species. Susceptibility testing was performed after culture; marketed PCR assays detected mutations in the CYP51A gene associated to resistance.

RESULTS: Within 3 years, 1555 BAL samples were processed, including 413 samples from 387 immunosuppressed patients. IA diagnosis was no-IA, possible, probable or proven IA in 326, 23, 37 and 1 patients, respectively. PCR assays sensitivity for Aspergillus detection ranged from 61% to 74%, below GM (87%), but contrasting with 47% for cultures. Combining PCR to EORTC/MSG criteria increased the sensitivity to 100%. Interestingly, tests performance in non-hematological patients ranged from 60% to 75%, and were higher than in hematological patients, and those with prior exposure to antifungals. All 16 isolates of Aspergillus fumigatus were susceptible; PCR did not detect any resistance marker in the 37 A. fumigatus PCR-positive samples.

CONCLUSION: The molecular detection of Aspergillus directly in BAL samples greatly improved the diagnosis of IA, particularly in non-hematological patients.