In vivo commensal control of Clostridioides difficile virulence

We illustrate how metabolically distinct species of Clostridia can protect against or worsen Clostridioides difficile infection, modulating the pathogen's colonization, growth, and virulence to impact host survival. Gnotobiotic mice colonized with the amino acid fermenter Paraclostridium bifermentans survived infection while mice colonized with the butyrate-producer, Clostridium sardiniense, more rapidly succumbed. Systematic in vivo analyses revealed how each commensal altered the gut nutrient environment, modulating the pathogen's metabolism, regulatory networks, and toxin production. Oral administration of P. bifermentans rescued conventional mice from lethal C. difficile infection via mechanisms identified in specifically colonized mice. Our findings lay the foundation for mechanistically informed therapies to counter C. difficile disease using systems biologic approaches to define host-commensal-pathogen interactions in vivo. (i) Gnotobiotic mice were colonized with Paracolostridium bifermentans ATCC 638 or Clostridium sardiniense DSM 599 7 days prior to infection with 10^3 spores of Clostridioides difficile ATCC 43255. Cecal contents were collected an analyzed at the indicated timepoints. Compared to mono-associated (MA) infections, mice pre-colonized with P. bifermentans showed significant protection from severe disease, whereas those pre-colonized with C. sardiniense more quickly succumbed. Additional metabolomic experiments were coupled with these results and suggest that metabolic competition and symbiosis, respectivevly, in the gut play a major role in C. difficile disease. Mice were pre-colonized with a gut commensal bacterial species, then infected with C. difficile. (ii) Csar In vivo commensal control of Clostridioides difficile virulence, Clostridium sardiniense transcriptome: Gnotobiotic mice were colonized with Clostridium sardiniense DSM 599 7 days prior to infection with 10^3 spores of Clostridioides difficile ATCC 43255. Cecal contents were collected an analyzed at the indicated timepoints. Compared to mono-associated (MA) infections, mice pre-colonized with P. bifermentans showed significant protection from severe disease, whereas those pre-colonized with C. sardiniense more quickly succumbed. Additional metabolomic experiments were coupled with these results and suggest that metabolic competition and symbiosis, respectivevly, in the gut play a major role in C. difficile disease. Mice were pre-colonized with a gut commensal bacterial species, then infected with C. difficile. (iii) PBI In vivo commensal control of Clostridioides difficile virulence, Paraclostridium bifermentans transcriptome: Gnotobiotic mice were colonized with Paracolostridium bifermentans ATCC 638 7 days prior to infection with 10^3 spores of Clostridioides difficile ATCC 43255. Cecal contents were collected an analyzed at the indicated timepoints. Compared to mono-associated (MA) infections, mice pre-colonized with P. bifermentans showed significant protection from severe disease, whereas those pre-colonized with C. sardiniense more quickly succumbed. Additional metabolomic experiments were coupled with these results and suggest that metabolic competition and symbiosis, respectivevly, in the gut play a major role in C. difficile disease.