Most Salmonella infections occur through ingestion of contaminated food. In the US, about 40,000 cases of Salmonella infection are reported each year. Effective, fast and reliable methods of Salmonella identification of are crucial. Well over 2,500 Salmonella known subtypes or serovars have been described. Salmonella contaminations are often caused by different Salmonella strains. Numerous methods, traditional and rapid alike, have been developed as alternate detection and identification methods. Although most tests claim to produce results within 48 hours, a comprehensive strain identification for traceback analysis can last up to three weeks. Individual serovars can be typed by phage typing, antibiotic resistance profiling, and immunomagnetic separation, to name a few. Based on spectral pattern recognition of mass spectra of Salmonella strains, the methodology developed in this study can be used to distinguish and identify Salmonella enterica subsp. enterica serovar Typhimurium strains. The spectra pool comprised 40 mass spectra acquired of each of the four different Salmonella Typhimurium strains used in this study. In brief, acquired mass spectra of Salmonella Typhimurium strains were subject to lossless data compression, then preprocessed using custom-made software for improved strain identification using weighted spectral pattern recognition. Spectra belonging to a particular Salmonella Typhimurium strain would cluster in principal component analysis (PCA) plots, and can thus be distinguished. A complete Salmonella strain identification can take up to 40 minutes. This includes purification of bacterial suspensions, cell counting, adjustment of bacterial cell concentrations, sample preparation, spectra acquisition, spectra preprocessing and analysis. In this study, two of the four Salmonella Typhimurium strains, originally thought to be different, were actually found to be identical. This newly developed Salmonella strain identification methodology is quick, affordable, and reliable.

Distinction of <i>Salmonella enterica</i> subsp. enterica serovar typhimurium strains through pattern recognition of weighted mass spectra

247th National Meeting (2014)

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Distinction of Salmonella enterica subsp. enterica serovar typhimurium strains through pattern recognition of weighted mass spectra