48. Rapid Identification of Filamentous Fungi by MALDI-TOF Mass Spectrometry using the VITEK® MS Mould Kit
Session: Posters in the Park: Posters in the Park
Wednesday, October 3, 2018: 5:30 PM
Room: N Hall D Opening Reception and Posters in the Park Area
Background: Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry is a new powerful tool for the routine identification of bacteria and yeasts in clinical specimens. Its application to identify molds however, which requires additional preparation steps, is still under evaluation and not yet implemented in most laboratories. Our study aimed to evaluate the performance and practicality of the VITEK®MS system to identify clinical and environmental isolates of molds in a routine microbiology laboratory in Chile. Methods: Isolates derived from three laboratories in Santiago and Valparaíso, Chile, and included rare species cultivated from clinical and environmental samples. For MALDI-TOF identification, specimens were cultured under standard conditions on potato dextrose agar and tested within 2-4 days of visible growth. Samples were prepared with VITEK®MS Mould Kit according to the manufacturer`s instructions and analyzed by the VITEK®MS system, database v3.0 (BioMérieux). Results were compared to species diagnosis obtained by morphological and molecular methods in a national reference laboratory for mycology. Results: A total of 44 isolates filamentous fungi were tested, including different species of Aspergillus (9), Fusarium (3), Trichophyton (2), Rhizopus (2), and Penicillium (2), as well as Sarocladium strictum, Lichteimia corymbifera, Pseudallescheria boydii, Sporothrix globose and S. chilensis, Alternaria alternata, Epidermophyton floccosum, and Coccidioides posadasii. VITEK MS provided correct identification in 42 (95.5%) of strains; 28 (63.6%) reached species, 12 (27.2%) species complex, and 2 (4.5%) genus level. Two isolates were not identified (Aspergillus tritici and Sporothrix chilensis); both species are not included in the current VITEK®MS database, and the system indicated that identification was not achieved. Conclusion: VITEK®MS provided a rapid and accurate diagnosis for most of the tested filamentous fungi without erroneous results. The manufacturer´s mould preparation kit was easy to use, but added significant additional expenses. The evaluated system permitted a reliable identification of a group of fungi which is usually not identifiable under routine conditions of a microbiological laboratory.
Inia Pérez, MD, Universidad del Desarrollo, Santiago, Chile, Rodrigo Cruz, MD, Universidad de Valparaiso, Valparaiso, Chile, Carmen Varela, MLT, Microbiology, Clinica Alemana de Santiago, Santiago, Chile, María Diaz, MLT, Mycology, Universidad de Chile, Santiago, Chile, Thomas Weitzel, MD, Clinica Alemana, Santiago, Chile and Lorena Porte, MD, Clinica Alemana De Santiago, Santiago, Chile

Disclosures:

I. Pérez, None

R. Cruz, None

C. Varela, None

M. Diaz, None

T. Weitzel, None

L. Porte, None

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