By David Wild

Originally published by our sister publication, Gastroenterology & Endoscopy News

Klebsiella pneumoniae, which is found in higher concentrations in patients with inflammatory bowel disease, enhances the growth of Clostridioides difficile and worsens colonic inflammation in the presence of C. difficile infection, according to new research. 

“When C. difficile infection is superimposed on colitis, it synergistically worsens both conditions,” researcher Taylor Ticer, a PhD candidate at the Medical University of South Carolina, in Charleston, and colleagues reported at the 2022 Crohn’s and Colitis Congress (Inflamm Bowel Dis 2022;28[suppl 1]:S69).

To better understand why this connection exists, the researchers examined the dynamics of K. pneumoniae and C. difficile. The former pathogen is found in the mucus-associated microbiota of C. difficile patients and also is “present at increased levels in IBD patients,” the investigators noted.

To test their hypothesis that K. pneumoniae promotes intestinal colonization of C. difficile and possibly worsens inflammation in IBD patients, they cultured 12 strains of K. pneumoniae with four ribotypes of C. difficile and observed growth over 24 hours.

The analysis found all K. pneumoniae strains enhanced the growth of all C. difficile strains, “suggesting that K. pneumoniae could produce metabolites that enhanced C. difficile growth,” they wrote.
Indeed, when they performed metabolomic analysis, Dr. Tice’s team found K. pneumoniae changed C. difficile metabolism, specifically moving it away from reliance on carbohydrates to using other sources for energy.

To examine how K. pneumoniae affects C. difficile infection and inflammation in vitro, they employed colonic organoids and found significantly higher levels of pro-inflammatory molecules in these organoids when C. difficile and K. pneumoniae were incubated together rather than separately.

According to the investigators, the findings "suggest that K. pneumoniae can influence C. difficile metabolism and exacerbate inflammation.”