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J. Mol. Micro. Biotechnol. 3: 103-112
Phyloproteomics: Species Identification of Enterobacteriaceae
Using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry
Gregory C. Conway, Sandra C. Smole, David A. Sarracino, Robert D. Arbeit, Peter E. Leopold
To evaluate matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS) as a tool for rapid identification of common clinical
bacterial isolates, we analyzed 25 carefully selected isolates of pathogenic
Escherichia coli (E. coli) and additional
Enterobacteriaceae members. Organisms were
prepared according to clinical microbiological protocols and analyzed with minimal additional processing. Spectra were reproducible from preparation to preparation
and comprised 40-100 peaks primarily representing intracellular proteins with masses up to 25 kDa. Spectra of 14 genetically diverse bacteremic isolates of
E. coli were compared with isolates representing other genera within the
Enterobacteriaceae family. Using a new spectrum comparison algorithm,
E. coli isolates were closely related to each other and were readily distinguishable from other
Enterobacteriaceae, including
Salmonella and Shigella. Presently, the methodology permits
the analysis of 40 unknown isolates per hour per instrument. These results suggest that MALDI-ToF MS offers a rapid and reliable approach for performing
phyloproteomics i.e., identification of unknown bacterial isolates based on similarities within protein biomarker databases.
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