Comparative Evaluation of Two Commercial Matrix-Assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) Mass Spectrometry Platforms for Identification of Clinically Relevant Moulds

A. N. Schuetz, A. Robertson, E. Miranda, J. Choudhury, R. C. Walchak, N. L. Wengenack, S. Jenkins, Y. W. Tang, D. Larone, E. N. Babady


Background: MALDI-TOF mass spectrometry (MS) has revolutionized microbial pathogen identification in many clinical laboratories. Literature for use of MALDI-TOF MS for mould identification is limited. We evaluated the comparative performances of two MALDI-TOF MS systems: the Bruker Biotyper (Bruker Daltonics Inc., Billerica, MA) and Vitek MS (bioMérieux, Durham, NC) for identification of clinically relevant moulds using manufacturer-provided databases. Methods: A variety of 66 mould isolates recovered from cultures at Weill Cornell Medical Center (WCMC), Memorial Sloan-Kettering Cancer Center (MSKCC) and Mayo Clinic were included. All isolates were tested on the Bruker Biotyper by WCMC and on Vitek MS by MSKCC. Moulds were sub-cultured from plates into a liquid Sabouraud broth for Bruker, while moulds were run directly off plates for Vitek. Results: The Bruker Biotyper identified 49/66 isolates with 37 (56%) correct identifications. Vitek identified 38/66 isolates with 30 (45%) correct identifications. The majority of incorrect identifications by Bruker were called Aspergillus spp. There were more unmatchable results for Vitek than Bruker (29 vs. 17, respectively). The agreement for correct identification between the two MS platforms was 71% (22/31). Conclusions: MALDI-TOF MS has potential to significantly impact mold identification in clinical laboratories. Identification from solid media was more rapid than conventional methods (minutes/hours vs. days). Vitek showed more unmatched results, while Bruker more often resulted in incorrect Aspergillus identifications for moulds in entirely different categories, such as other hyaline moulds, dematiaceous and dermatophytes. The majority of the unmatched isolates by both systems were comprised of Mucorales, dematiaceous and hyaline moulds other than Aspergillus and Fusarium. Our study demonstrates that additional effort in developing comprehensive databases is needed to improve the identification of moulds for both systems.

abstract No: 


Full conference title: 

American Society for Microbiology General Meeting
    • ASM 113th (2013)