Selenite broth

Feces samples collected from carnivores were inoculated on 10 mL of peptone broth (Oxoid, Monterrey, Mexico) and incubated at 37 °C for 18 h. After, 1 mL was transferred to 10 mL of selenite broth (Merck, Branchburg, NJ, USA) and incubated at 37 °C for 20 h. Each selenite broth was seeded on Salmonella-Shigella agar (Merck, Branchburg, NJ, USA) and MacConkey agar (Merck, Branchburg, NJ, USA) and incubated for 24 h at 37 °C. All colonies with characteristic morphology of Salmonella spp. were transferred to Salmonella-Shigella agar and incubated at 37 °C for 24 h. Finally, microorganisms were identified by standard microbiology methods. Salmonella enterica Typhimurium ATCC 14028 was included in all bacteriological procedures, PCR, and invasion assays, as a reference strain.