Discrimination of Salmonella enterica serotypes by Fourier transform infrared spectroscopy

Salmonella continues to be an important cause of foodborne infections in humans throughout the world. The precise nature of the infection depends on the specific combination of host and Salmonella serotypes, some of them being highly pathogenic. Fourier transform infrared (FT-IR) spectroscopy together with chemometric techniques were used in this study to discriminate closely related S. enterica serotypes. Intact cells of 26 different serotypes belonging to serogroups B, C1, C2–C3 and D1 (Enteritidis, Typhimurium, Bredeney, Goldcoast, Rissen, Hadar, Derby, Essen, Virchow, Mbandaka, Menden, Agona, Brikama, Saintpaul, Infantis, Braenderup, Mikawasima, Brandenburg, Heidelberg, Indiana, Norwich, Bardo, Bovismorbificans, Istanbul, Newport and Blockley) were examined by FT-IR spectroscopy in transmittance mode and classified based on the agglutination pattern reactions using the Kauffmann–White classification scheme. Using FT-IR spectra in the 1200–900 cm− 1 range (outer membrane polysaccharides) allowed to correctly classify all isolates according to the four analysed serogroups. A discrimination analysis applied within each serogroup, demonstrated that it was also possible to differentiate between the different serotypes. Results demonstrate that application of FT-IR spectroscopy together with chemometric methods has considerable potential to effectively fulfil the current requirements for fast and straightforward differentiation of S. enterica serotypes.