Evaluation of Enrichment and Identification Media for Isolation of Common Bovine Salmonella Serotypes

Salmonellosis is an important cause of diarrhea in humans and animals, which can lead to death in severe cases. Rapid and efficient detection of Salmonella spp. is essential to limit the spread of disease. Many enrichment procedures have been described for the isolation of Salmonella, and often include variations on Rappaport-Vassiliadis medium, which is recommended by the Food and Drug Administration (FDA). The current procedures vary in incubation temperature, incubation time, and type of media used for identification of Salmonella. This project compared four procedures for enrichment and identification of common bovine Salmonella serotypes. We determined the best procedure for isolation and identification of the most common serotypes from cattle including S. Typhimurium, S. Dublin, S. Cerro and S. Montevideo. To do so, we compared Rappaport-Vassiliadis broth (RV), Rappaport-Vassiliadis R10 broth (R10), Tetrathionate broth (TT), and Selenite-Cysteine broth (SC) for isolation of the Salmonella serotypes and Xylose lysine tergitol 4 agar (XLT-4) and Xylose lysine deoxycholate agar (XLD) for identification of the Salmonella serotypes. Incubation temperature and incubation time were also compared. We hypothesized that R10 would provide the best enrichment, and XLD agar the best identification method for these specific strains. After identifying the best procedure for enrichment of pure cultures, future studies will include determining the sensitivity of the best procedure for use on fecal and animal tissue samples submitted to the UVDL. This will provide a practical evaluation of the optimized enrichment procedure against actual clinical samples.