Wednesday 5 July 2023

Citrobacter rodentium: A role inflammatory disease

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Pathogenic bacteria use a sugar in the intestinal mucus layer to infect the gut, a new study shows. University of British Columbia researchers have demonstrated how the sugar sialic acid, which makes up part of the protective intestinal mucus layer, fuels disease-causing bacteria in the gut.


The findings suggest a potential treatment target for intestinal bacterial infections and a range of chronic diseases linked to gut bacteria, including inflammatory bowel disease (IBD), celiac disease, irritable bowel syndrome and short bowel syndrome.


Inflammatory diseases such as IBD are on the rise in children, and because of their immature immune systems, kids are more susceptible to gut bacterial infections.


For the study, the researchers examined Citrobacter rodentium, an intestinal bacterial pathogen of mice that's used to model infections with human E. coli. The team discovered that the bacteria have genes involved in sialic acid consumption, and when these genes are removed, the bacteria's growth is impaired.


Citrobacter rodentium is a mucosal pathogen of mice that shares several pathogenic mechanisms with enteropathogenic Escherichia coli (EPEC) and enterohaemorrhagic E. coli (EHEC), which are two clinically important human gastrointestinal pathogens.



Further investigation revealed that upon consuming the sugars, the bacteria produced two special virulence proteins that help the bacteria cross the colonic mucus layer and stick to the underlying epithelial cells. The findings reveal how the bacteria can change over time and actually worsen disease.


The researchers are now examining the role other sugars in the gut may play in feeding pathogenic bacteria. They are also looking for resident good bacteria (probiotics) that could outcompete the dangerous bacteria, stealing the sugars away from them.


Further research will explore potential interactions between resident and pathogenic bacteria. Pathogenic bacteria can't access the sugars on their own and thus, some of the normally harmless resident bacteria must serve as accomplices. A better understanding of these interactions could provide new ways to block pathogenic bacteria.




Qiaochu Liang, Caixia Ma, Shauna M. Crowley et al. Sialic acid plays a pivotal role in licensing Citrobacter rodentium’s transition from the intestinal lumen to a mucosal adherent niche. Proceedings of the National Academy of Sciences, 2023; 120 (28) DOI: 10.1073/pnas.2301115120


Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (

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