title: MALDI-TOF mass spectrometry for rapid identification of clinical fungal isolates based on ribosomal protein biomarkers.
abstract: This study aimed to evaluate the identification of clinical fungal isolates (yeast and molds) by protein profiling using Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS). A total of 125 clinical fungal culture isolates (yeast and filamentous fungi) were collected. The test set included 88 yeast isolates (Candida albicans, Candida glabrata, Candida guilliermondii, Candida kefyr, Candida krusei, Candida parapsilosis, Candida rugosa, Candida tropicalis and Cryptococcus neoformans) and 37 isolates of molds (Alternaria spp., Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Cunninghamella spp., Histoplasma capsulatum, Microsporum gypseum, Microsporum nanum, Rhizomucor spp. and Trichophyton spp.). The correlation between MALDI TOF MS and conventional identification for all these 125 fungal isolates included in the study was 87.2% at the species level and 90.4% at the genus level. MALDI TOF MS results revealed that the correlation in yeast (n=88) identification was 100% both at the genus and species levels whereas, the correlation in mold (n=37) identification was more heterogeneous i.e. 10.81% isolates had correct identification up to the genus level, 56.7% isolates had correct identification both at the genus and species levels, whereas 32.42% isolates were deemed Not Reliable Identification (NRI). But, with the modification in sample preparation protocol for molds, there was a significant improvement in identification. 86.4% isolates had correct identification till the genus and species levels whereas, only 2.7% isolates had Not Reliable Identification. In conclusion, this study demonstrates that MALDI-TOF MS could be a possible alternative to conventional techniques both for the identification and differentiation of clinical fungal isolates. However, the main limitation of this technique is that MS identification could be more precise only if the reference spectrum of the fungal species is available in the database.
authors.affiliation: Department of Microbiology, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Panda
authors.affiliation: Department of Medical Microbiology, Post Graduate Institute, Chandigarh 160012, India.
authors.forename: Anup K
authors.initials: AK
authors.lastname: Ghosh
authors.affiliation: Department of Microbiology, All India Institute of Medical Sciences, New Delhi 110029, India. Electronic address: mirdhabr2078@gmail.com.
authors.forename: Bijay R
authors.initials: BR
authors.lastname: Mirdha
authors.affiliation: Department of Microbiology, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Immaculata
authors.initials: I
authors.lastname: Xess
authors.affiliation: Department of Medical Microbiology, Post Graduate Institute, Chandigarh 160012, India.
authors.forename: Saikat
authors.initials: S
authors.lastname: Paul
authors.affiliation: Department of Microbiology, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Jyotish C
authors.initials: JC
authors.lastname: Samantaray
authors.affiliation: Department of Microbiology, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Alagiri
authors.initials: A
authors.lastname: Srinivasan
authors.affiliation: Department of Microbiology, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Shehla
authors.initials: S
authors.lastname: Khalil
authors.affiliation: Department of Microbiology, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Neha
authors.initials: N
authors.lastname: Rastogi
authors.affiliation: Department of Microbiology, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Yubhisha
authors.initials: Y
authors.lastname: Dabas
mesh_terms: D015415:Biomarkers; D005656:Fungal Proteins / Q000032:analysis*; D005658:Fungi / Q000737:chemistry* / Q000145:classification* / Q000302:isolation & purification; D006801:Humans; D009181:Mycoses / Q000382:microbiology; D012269:Ribosomal Proteins / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D015415:Biomarkers; D005656:Fungal Proteins; D012269:Ribosomal Proteins
keywords: Fungal isolates; Identification; Matrix assisted laser desorption ionization-time of flight mass spectrometry; Rapid