Fusobacterium nucleatum adheres to Clostridioides difficile via the RadD adhesin to enhance biofilm formation in intestinal mucus

MA Engevik, HA Danhof, J Auchtung, BT Endres… - Gastroenterology, 2021 - Elsevier
Gastroenterology, 2021Elsevier
Background & Aims Although Clostridioides difficile infection (CDI) is known to involve the
disruption of the gut microbiota, little is understood regarding how mucus-associated
microbes interact with C difficile. We hypothesized that select mucus-associated bacteria
would promote C difficile colonization and biofilm formation. Methods To create a model of
the human intestinal mucus layer and gut microbiota, we used bioreactors inoculated with
healthy human feces, treated with clindamycin and infected with C difficile with the addition …
Background & Aims
Although Clostridioides difficile infection (CDI) is known to involve the disruption of the gut microbiota, little is understood regarding how mucus-associated microbes interact with C difficile. We hypothesized that select mucus-associated bacteria would promote C difficile colonization and biofilm formation.
Methods
To create a model of the human intestinal mucus layer and gut microbiota, we used bioreactors inoculated with healthy human feces, treated with clindamycin and infected with C difficile with the addition of human MUC2-coated coverslips.
Results
C difficile was found to colonize and form biofilms on MUC2-coated coverslips, and 16S rRNA sequencing showed a unique biofilm profile with substantial cocolonization with Fusobacterium species. Consistent with our bioreactor data, publicly available data sets and patient stool samples showed that a subset of patients with C difficile infection harbored high levels of Fusobacterium species. We observed colocalization of C difficile and F nucleatum in an aggregation assay using adult patients and stool of pediatric patients with inflammatory bowel disease and in tissue sections of patients with CDI. C difficile strains were found to coaggregate with F nucleatum subspecies in vitro; an effect that was inhibited by blocking or mutating the adhesin RadD on Fusobacterium and removal of flagella on C difficile. Aggregation was shown to be unique between F nucleatum and C difficile, because other gut commensals did not aggregate with C difficile. Addition of F nucleatum also enhanced C difficile biofilm formation and extracellular polysaccharide production.
Conclusions
Collectively, these data show a unique interaction of between pathogenic C difficile and F nucleatum in the intestinal mucus layer.
Elsevier