Identification of Salmonella Enterica Serovar Enteritidis Vaccine Strains by Fourier Transform Infrared Spectroscopy
In cases of salmonellosis in humans, the most frequently isolated serovars of Salmonella enterica are Enteritidis (serogroup D1) and Typhimurium (serogroup B). In order to control the main sources of this zoonotic pathogen, poultry populations are treated with attenuated live vaccines. The distinction between vaccine strains and pathogenic wild type strains requires specific assays. For differentiation of two poultry vaccine serogroup D1 strains, TAD Salmonella vac® E and Salmovac SE, from other salmonellae of serogroup D1, a new method was developed by means of Fourier transform infrared (FT-IR) spectroscopy and artificial neural networks (ANN). To train the ANN, 548 spectra of 74 serogroup D1 isolates were used. Both vaccine strains could be differentiated from wild type strains of the same serogroup with an error rate of less than 1 % in replicate analyses. Moreover, this study revealed the potential of FT-IR spectroscopy for identifying salmonella strains to trace contamination routes.
The Salmonella (S.) serovars Enteritidis and Typhimurium are the two most frequent serovars causing salmonellosis in humans in Germany. In this country a considerable source of these pathogens are poultry popu-lations. 29 % of larger (1000+ animals) laying hen holdings were infected with Salmonella in the years 2004 to 2005. European efforts have striven to reduce the prevalence of these Salmonella types on affected farms as required by regulation, which recommends precautionary vaccination of the animals as a possible measure.