DNA fingerprinting of S. typhimurium from a pig longitudinal study

A 400 sow farrow-to-finish farm was sampled for 6 consecutive years to determine the persistence of Salmonella Typhimurium (STM) DT104. Pulsed-field gel electrophoresis, plasmid DNA analysis and antibiotic resistance phenotyping was carried out on selected STM strains, isolated from the farm during the time of the study. Clonal persistence as well and introduction of new clones from external sources were proven to be the main mechanisms by which salmonella infection was maintained in the farm