TABLE 3.
Conventional identification algorithm versus MALDI-TOF MS identification for 165/200 clinical mold isolates of the prospective study
| Conventional identification algorithma | No. of isolates | No. (%) of concordant identifications by MALDI-TOF MS atb: |
Discrepant identification by MALDI-TOF MS | Resolution of discrepancy | |
|---|---|---|---|---|---|
| Genus level (cutoff, 1.7) | Species level (cutoff, 1.7) | ||||
| Aspergillus fumigatus | 68 | 68 (100.0) | 68 (100.0) | ||
| Penicillium sp. | 30 | 30 (100.0) | |||
| Fusarium sp. | 10 | 10 (100.0) | |||
| Aspergillus flavus | 10 | 10 (100.0) | 10 (100.0) | ||
| Aspergillus versicolor | 9 | 9 (100.0) | 7 (77.8) | Aspergillus unguis (n = 2) | A. versicolor and A. unguis are phenotypically closely related and not distinguished by the conventional identification algorithm |
| Aspergillus terreus | 7 | 7 (100.0) | 7 (100.0) | ||
| Aspergillus sp. | 4 | 4 (100.0) | |||
| Cladosporium sp. | 3 | 3 (100.0) | |||
| Alternaria sp. | 3 | 3 (100.0) | |||
| Aspergillus glaucus | 3 | 3 (100.0) | 1 (33.3) | Aspergillus sp. (n = 2) | No differentiation of A. glaucus and A. amstelodami by MALDI-TOF MS and ITS sequence analysis |
| Botrytis sp. | 3 | 3 (100.0) | |||
| Rare isolatesc | 15 | 12 (80.0) | 10 (66.7) | ||
| Aspergillus nidulans | Aspergillus fumigatus (n = 1) | Phenotypic misidentification | |||
| Acremonium sp. | Aspergillus fumigatus (n = 1) | Contamination of liquid culture for MALDI-TOF MS identification with A. fumigatus | |||
| Beauveria sp. | Beauveria bassiana (n = 1) | ITS sequence analysis confirmation of Beauveria bassiana | |||
| Paecilomyces sp. | Geosmithia argillacea (n = 1) | Phenotypic misidentification | |||
| Phoma sp. | Chaetomium globosum (n = 1) | Phenotypic misidentification | |||
| Total | 165 | 162 (98.2) | 103 (62.4) | ||
a
Identification algorithm according to the work of Ciardo et al. (4).
b
MALDI-TOF MS identification applying a genus and species cutoff of 1.7 with the Filamentous Fungi Library 1.0 (Bruker).
c
Isolates with n of ≤2, including Acremonium sp., Arthrinium phaeospermum, Aspergillus nidulans, Aspergillus niger, Aspergillus ochraceus, Botrytis sp., Phoma sp., Scedosporium apiospermum, Chaetomium sp., Paecilomyces lilacinum, Paecilomyces sp., and Scopulariopsis brevicaulis. Only those with discrepant identification of the conventional identification algorithm and MALDI-TOF MS are shown.