Early Salmonella Typhimurium infection in pigs disrupts Microbiome composition and functionality principally at the ileum mucosa.
Argüello H, Estellé J, Zaldívar-López S, Jiménez-Marín Á, Carvajal A, López-Bascón MA, Crispie F, O'Sullivan O, Cotter PD, Priego-Capote F, Morera L, Garrido JJ
Sci Rep. May 2018. doi: 10.1038/s41598-018-26083-3
COMMENT: Salmonella is a major foodborne pathogen with a significant number of cases and outbreaks every year. Poultry meat, eggs and pork are the main sources of human salmonellosis. The host microbiota may play a role in resistance to, and may also be indirectly responsible from some of the consequences of, Salmonella infection.
To investigate this, Arguello et al. used 16S rRNA metagenomic sequencing to determine the changes in the gut microbiota of pigs in response to infection by Salmonella Typhimurium at three locations: ileum mucosa, ileum content and faeces. Early infection (2 days post-infection) impacted on the microbiome diversity at the mucosa, reflected in a decrease in representatives of the generally regarded as desirable genera (i.e., Bifidobacterium and Lactobacillus). Severe damage in the epithelium of the ileum mucosa correlated with an increase in synergistic (with respect to Salmonella infection; Akkermansia) or opportunistically pathogenic bacteria (Citrobacter) and a depletion in anaerobic bacteria (Clostridium spp., Ruminococcus, or Dialister).
Predictive functional analysis, together with metabolomic analysis revealed changes in glucose and lipid metabolism in infected pigs. The observed changes in commensal healthy microbiota, including the growth of synergistic or potentially pathogenic bacteria and depletion of beneficial or competing bacteria, could contribute to the pathogen's ability to colonize the gut successfully.
As the authors point out in the conclusion:
We illustrate that the disruption of microbiota composition triggered by infection also has apparent consequences for the microbiome function, with a general downshift of activities early after infection and additional changes in relevant metabolic routes. Future research should focus on identifying the key host response-related factors that prompt changes in the microbiome structure, which might help to establish novel microbiome restoration strategies to limit the impact of Salmonella infection in pigs and, ultimately, zoonotic infections in humans.