[Fungal nucleic acid detection for invasive aspergillosis]

Abstract

A universal PCR-assay for the detection of fungal DNA was compared with microscopy and culture for the diagnosis of invasive aspergillosis using 78 samples from 42 patients. Eighteen patients were suffering from invasive aspergillosis, 5 patients were colonized with Aspergillus in the respiratory tract, 19 patients did not show any sign of aspergillosis. Samples from 6 of the 18 patients with invasive aspergillosis were microscopically positive with true mycelia, 15 of 18 grew Aspergillus in culture, 16 of 18 were PCR-positive. The combination of microscopy and culture led to the diagnosis in 17 of 18 patients, the combination of microscopy and PCR in 16 of 18 and the combination of culture and PCR in all the 18 patients. For 3 of 18 patients, PCR was the diagnostic key: in 2 biopsies the histologically detected fungal elements were identified as Aspergillus, in 3 bronchial lavages from 1 patients nothing but PCR was positive for Aspergillus. Four out of 5 culture positive patients with Aspergillus colonization were also PCR positive; one out of 19 patients without aspergillosis was culture positive, 3 out of 19 were falsely PCR positive. Candida colonization in the upper respiratory tract or Pneumocystis carinii pneumonia did not lead to false positive Aspergillus-PCR results. In conclusion, the evaluated fungal PCR-assay can supplement conventional methods for the diagnosis of invasive aspergillosis.