Attenuation of <i>Clostridioides difficile</i> Infection by <i>Clostridium hylemonae</i>

<i>Clostridioides difficile</i> infection (CDI) is a bacterial infection of the colon that can cause diarrhea and colitis. The use of antimicrobials disrupts the intestinal microbiota, weakening colonization resistance and creating an environment in which <i>C. difficile</i> can establish infection. It is, therefore, necessary to identify specific bacteria that are helpful for the recovery of the intestinal microbiota in individuals with CDI. Previous studies have identified several strains that showed a negative correlation with <i>C. difficile</i>. Among these strains, <i>C. hylemonae</i> DSM 15053, which possesses the <i>bai</i> operon similar to <i>Clostridium scindens</i>, was selected. To test this hypothesis, we utilized a CDI mouse model and evaluated the inhibitory effect of <i>C. hylemonae</i> DSM 15053. Furthermore, to gain insights into the underlying mechanisms, we performed gut microbiota analysis. Contrary to our expectations, <i>C. hylemonae</i> DSM 15053 did not significantly produce SBAs. Interestingly, however, microbial diversity and richness were significantly higher in the <i>C. hylemonae</i> DSM 15053-treated group compared with the PBS control group. In addition, we observed a higher abundance of the genera <i>Phocaeicola</i>, <i>Akkermansia</i>, and <i>Parabacteroides</i> in the <i>C. hylemonae</i> DSM 15053 group. Moreover, metagenomic and metabolomic analyses revealed that <i>C. hylemonae</i> DSM 15053 mitigates CDI through a mechanism distinct from that of <i>C. scindens</i> KCTC 5591, which primarily functions as a regulator of bile acid metabolism.