| Affiliation: | 1. Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand;2. Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand Department of Biology, Health and Medicine, University of Manchester, Manchester, UK;3. Diagnostic Laboratory, Maharaj Nakorn Chiang Mai Hospital, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand;4. Department of Veterinary Bioscience and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand;5. Division of Food Biotechnology, National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathum Thani, Thailand |
| Abstract: | Salmonella enterica serovar Typhimurium (S. Typhimurium [STM]) is a leading cause of nontyphoidal salmonellosis (NTS) worldwide. The pathogenesis of NTS has been studied extensively using a streptomycin-pretreated mouse colitis model with the limited numbers of laboratory STM strains. However, the pathogenicity of the clinically isolated STM (STMC) strains endemic in Thailand in mice has not been explored. The aim of this study was to compare the pathogenicity of STMC strains collected from Northern Thailand with the laboratory STM (IR715) in mice. Five STMC isolates were obtained from the stool cultures of patients with acute NTS admitted to Maharaj Nakorn Chiang Mai Hospital in 2016 and 2017. Detection of virulence genes and sequence type (ST) of the strains was performed. Female C57BL/6 mice were pretreated with streptomycin sulfate 1 day prior to oral infection with STM. On Day 4 postinfection, mice were euthanized, and tissues were collected to analyze the bacterial numbers, tissue inflammation, and cecal histopathological score. We found that all five STMC strains are ST34 and conferred the same or reduced pathogenicity compared with that of IR715 in mice. A strain-specific effect of ST34 on mouse gut colonization was also observed. Thailand STM ST34 exhibited a significant attenuated systemic infection in mice possibly due to the lack of spvABC-containing virulence plasmid. |
