A MALDI-TOF assay for the rapid identification of Aspergillus and Candida sp. in clinical samples

L. Putignani, L. Mancinelli, F. Del Chierico, M. Onori, L. Coltella, P. Bernaschi, E. Fiscarelli, M. Argentieri, L. Pansani, S. Ranno, B. Lucignano, L. Dimiziani, C. Russo, D. Menichella

Author address: 

Rome, Macerata, IT


Objectives: Invasive mould infections are becoming worldwide increasing, resulting in significant morbidity and mortality especially in paediatric populations, immunocompromised and transplanted patients. Particularly the phyla Ascomycota, and Basidiomycota are involved in severe infections in children. The Ascomycota includes yeasts of the genera Saccharomyces, Pichia, and Candida and many filamentous fungi of the genera Aspergillus, Penicillium and Fusarium. The Basidiomycota Cryptococcus neoformans is an emerging opportunistic human pathogen. Identification of the increasing diversity of fungal pathogens by conventional methods (biochemical methods for yeast and phenotypic methods for mould) is often difficult, time-consuming and frequently, for unusual fungi, inconclusive. In our study, we exploited the MALDI-ToF MS (Matrix-assisted laser description ionization-time of flightmass spectrometry) Biotyper to for rapid and specific identification of fungal species from clinical specimens. Methods: 270 yeast and 80 mould fungi strains were collected from diversified clinical samples in our microbiology unit and grown on Sabouraud solid medium. Protein profiles were provided by using MALDIToF MS Biotyper for both clinical and reference strains, the latest purchased from the Centraalbureau voor Schimmelcultures (CBS) culture collection. Generated spectra were acquired and processed to produce appropriate species identification. The results were compared to conventional biochemical and phenotyping identifications in order to produce concordance data. When appropriate, MALDI-TOF-based results were compared to sequencingbased identification analysis (D2 LSU 28S rDNA). Results: MALDI-Tof MS provided the correct yeast identification with a sensitivity of 95% and specificity of 94% compared to conventional methods. For mould identification the MALDI-ToF MS provided a 80% of sensitivity, due to the absence of appropriate reference species in the database. The MALDI-ToF-MS identifications provided 100% of concordance with the 28S rDNA D2-LSU-based sequencing analysis for all the analysed isolates. Conclusions: This study provides a fast and reliable method, based on MALDI-ToF MS detection, for the identification of fungal species in clinical samples. This procedure might overcome current diagnostic tests and may represent a new frontier for the rapid and specific management of fungal infections in paediatric patients.

abstract No: 


Full conference title: 

20th European Congress of Clinical Microbiology and Infectious Diseases
    • ECCMID 20th (2010)