MALDI-TOF mass spectrometry as a tool for differentiation of invasive and noninvasive Streptococcus pyogenes isolates

• Authors: Hercules Moura, Centers for Disease Control and Prevention; Adrian R. Woolfitt, Centers for Disease Control and Prevention; Maria G. Carvalho, Centers for Disease Control and Prevention; Antonis Pavlopoulos, Centers for Disease Control and Prevention; Lucia M. Teixeira, Universidade Federal do Rio de Janeiro; Glen Satten, Emory University; John R. Barr, Centers for Disease Control and Prevention
• Journal Title: FEMS Immunology and Medical Microbiology
• Volume: Volume 53, Number 3
• Publisher: Oxford University Press (OUP): Policy B - Oxford Open Option D | 2008-08-01, Pages 333-342
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.1111/j.1574-695X.2008.00428.x
• Subjects: Biology, Microbiology; Health Sciences, Immunology; Biology, Biostatistics
• Keywords: Science & Technology; Life Sciences & Biomedicine; Immunology; Infectious Diseases; Microbiology; matrix-assisted laser desorption/ionization time of flight mass spectrometry; biomarkers; protein fingerprints; Streptococcus pyogenes; ribosomal proteins; necrotizing fasciitis; ASSISTED-LASER-DESORPTION/IONIZATION; DESORPTION IONIZATION-TIME; MICROORGANISM IDENTIFICATION; RAPID IDENTIFICATION; PROTEIN BIOMARKERS; DATABASE SEARCH; BACTERIA; PROTEOMICS; STRAINS; CULTURE

Abstract

A novel mass spectral fingerprinting and proteomics approach using MALDI-TOF MS was applied to detect and identify protein biomarkers of group A Streptococcus (GAS) strains. Streptococcus pyogenes ATCC 700294 genome strain was compared with eight GAS clinical isolates to explore the ability of MALDI-TOF MS to differentiate isolates. Reference strains of other bacterial species were also analyzed and compared with the GAS isolates. MALDI preparations were optimized by varying solvents, matrices, plating techniques, and mass ranges for S. pyogenes ATCC 700294. Spectral variability was tested. A subset of common, characteristic, and reproducible biomarkers in the range of 2000-14 000 Da were detected, and they appeared to be independent of the culture media. Statistical analysis confirmed method reproducibility. Random Forest analysis of all selected GAS isolates revealed differences among most of them, and summed spectra were used for hierarchical cluster analysis. Specific biomarkers were found for each strain, and invasive GAS isolates could be differentiated. GAS isolates from cases of necrotizing fasciitis were clustered together and were distinct from isolates associated with noninvasive infections, despite their sharing the same emm type. Almost 30% of the biomarkers detected were tentatively identified as ribosomal proteins.