Lack of clonal relationship between non-typhi Salmonella strain types from humans and those isolated from animals living in close contact

Antibiogram patterns and chromosomal DNA typing were used to compare 151 non-typhoidal Salmonella spp. (NTS) isolated from patients and 78 from animals, environmental or food specimens obtained within or near the homes of patients with invasive salmonellosis. The majority of NTS from humans (137; 90.7%) were Salmonella enterica serotype Typhimurium (S. Typhimurium) and S. Enteritidis. Chicken specimens and feeds produced (24; 52.2%) S. Enteritidis, while S. Agona was the predominant (20; 77%) serovar among pigs and dairy cows. The majority (97; 64.2%) of NTS from humans were multidrug resistant, while NTS from cows, pigs, beef carcass swabs and sewers were fully susceptible to all antibiotics tested. Pulsed-field gel electrophoresis patterns of XbaI-digested genomic DNA of NTS from the humans and the chickens were different. However, S. Enteritidis from chickens, and S. Braenderup and S. Agona from cows and pigs were clustered together in one group. There was no significant relatedness between NTS isolates from humans and those from animals, food or the environment in close contact to humans.