Comparison of Fatty Acid Analysis with Serotype and Pulsed-Field Gel Electrophoresis for Typing S almonella Isolated from Retail Foods and Human

Abstract

Whole-cell fatty acid analysis by pyrolysis-gas chromatography/mass spectrometry was compared with pulsed-field gel electrophoresis (PFGE) and serotyping to determine the best suited method for identification of Salmonella strains. Forty-two isolates were analyzed and 10 fatty acids were identified in all of the tested strains. The main fatty acid component was n-hexadecanoic acid (C16:0), followed by cis-9-hexadecenoic acid (C16:1ω-7c), cis-10-heptadecenoic acid (C17:1ω-7c), tetradecanoic acid (C14:0), cis-10-nonadecenoic acid (C19:1ω-9c), trans-2-dodecenoic acid (C12:1ω-10t), cis-vaccenic acid (C18:1ω-8c), dodecanoic acid (C12:0), octadecanoic acid (C18:0) and 2-tridecanoic acid (E)-(C13:0). Whole-cell fatty acid analysis, PFGE and serotyping yielded 38, 35 and 29 types, respectively. Simpson's diversity indices of the three typing methods were 0.994, 0.985 and 0.943, respectively. PFGE grouped all the strains into 27 clusters based on 80% similarity. Fatty acid analysis was grouped into four clusters based on r = 0.8. Our findings indicate that whole-cell fatty acid analysis was found to help with rapid identification of Salmonella strains. Whole-cell fatty acid analysis was not only as portable as PFGE and serotyping but also more rapid and cost-effective. Practical Applications Foodborne diseases caused by Salmonella enterica represent an important public health problem worldwide. Therefore, tracing sporadic cases and outbreaks of Salmonella infection is important for epidemiological purposes. In this context, fatty acid analysis is a rapid and cost-effective method for identification and classification of Salmonella strains, and it can help expedite the process of foodborne outbreak investigation.