Implantation of a strain of Salmonella Typhimurium and a strain of Salmonella Rissen in a pig herd with recurrent clinical salmonellosis

Clinical salmonellosis is rare, even though it can occur in pig herds. The aim of this study was to investigate the diversity of Salmonella strains isolated in a farrow-to-finish pig herd suffering from recurrent clinical salmonellosis from 2018-2022. Different areas were sampled, such as farrowing, post-weaning and fattening rooms (with animals or after cleaning and disinfecting), feeding systems, corridors, the entry room, and the loading platform. Only three serotypes were identified: S. Typhimurium, S. Rissen and S. Livingstone. Because S. Livingstone was identified only at the farrowing level, we performed epidemiological monitoring of only S. Typhimurium and S. Rissen. DNA profiles were determined by molecular pulsotyping. It revealed that the same XbaI DNA profile was identified over the five year period for each serotype followed. We assumed that both strains have colonized the herd through either live species (sows, rodents, humans) or the farm building, dust or equipment. To our knowledge, this is the first time that a molecular epidemiological investigation of Salmonella strains has been performed in a pig herd suffering from recurrent clinical salmonellosis.