Objective: Galactomannan (GM) detection in bronchoalveolar lavage (BAL) is often described as an adjunctive diagnostic tool for the diagnosis of aspergillosis. Candida albicans infections are not a recognized cause of false-positive GM assay when performed on serum. However yeasts can be present in much larger amounts in BAL fluid than in serum. This study aimed at testing whether the presence of C. albicans would influence the GM assay results in patient BAL fluid. Methods: 70 BAL samples, originating from 66 patients hospitalized in various wards (haematology, intensive care units, pneumology), were routinely analyzed with direct microscopic examination (ME) by Giemsa and Gomori-Grocott stainings and culture. Platelia® -Aspergillus (BioRad) GM ELISA assay was performed retrospectively. BALs were splitted into four groups: (1) ME negative and culture negative (n = 20); (2) ME with pseudomycelia-yeasts and pure C. albicans culture (n = 23); (3) ME with hyphae and pure Aspergillus fumigatus culture (n = 10); (4) ME negative and A. fumigatus pure culture (n = 17). Platelia® - Aspergillus was performed as indicated by the manufacturer; the results were index values, a 0.5 positivity threshold was used as recommended in serum. Data were then analysed using increasing positivity threshold values. Results: Index values significantly differed among the four groups (p 1.5, and 6 (60.0%) were >8. In the group 4 (negative ME and A. fumigatus culture), 12 (70.6%) were >0.5. In the control groups 1 & 2, 15 were >0.5; 13 (86.6%) of those belonged to group 2 (pseudomycelia-yeasts and C. albicans). Conclusions: The presence of numerous pseudomycelia and yeasts in ME was associated with increased GM index values that were similar to those obtained for BALs with negative ME and A. fumigatus culture. In this case, GM results in BAL should be more cautiously interpreted. Whether a specific positivity threshold should be used when numerous yeasts and pseudomycelia are detected in the BAL fluid remains to be addressed.
Full conference title:
20th European Congress of Clinical Microbiology and Infectious Diseases
- ECCMID 20th (2010)