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.