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E. coli secret weapons for causing the worst possible infection

** E. coli secret weapons for causing the worst possible infection

Researchers Melissa Kendall, left, and Beth Melson found that E. coli bacteria use oxygen levels to sense where they are in the digestive system – and bind where they can do the most damage. Credit: Dan Addison, University Communications

A few researchers from the University of Virginia School of Medicine have revealed how E. coli seek out the most oxygen-free cracks in your colon to cause the worst infection possible.

The new discovery shows how the food-borne pathogen knows where and when to start colonizing the colon on its way to make you sick. Recognizing the low-oxygen small intestine environment, the dangerous bacterium gives itself the best odds of establishing a robust infection – one that punishes the host.

"Bacterial pathogens typically colonize a specific tissue in the host," said researcher Melissa Kendall of UVA & # 39; s Department of Microbiology, Immunology and Cancer Biology. "Therefore, as part of their infection strategies, bacterial pathogens are the exact time-propagation of proteins and toxins to these specific colonization niches in the human host. This allows the pathogens to conserve energy and avoid detection of our immune systems and ultimately cause disease.

"Knowing how bacterial pathogens sense where they are in the body may one day be able to prevent E. coli, as well as other pathogens, from knowing where it is inside a human host and letting it pass through the body without causing an infection. "

A bacterial gold lock

E. coli live naturally in our colon and most strains do us no harm. But there are several strains that can cause cramping, diarrhea, vomiting, even kidney failure and death. Children are at particular risk. As such, E. coli outbreaks appear regularly in the news. In July, for example, people in several states became ill E. coli linked to ground bison meat.

Kendall and graduate student Elizabeth M. Melson have shed important light on how harmful it is E. coli infections establish themselves in the body. The researchers outlined a process that the bacteria use to detect low oxygen levels in the colon and then produce proteins that allow E. coli to attach to host cells and establish infection.

Oxygen actually diffuses from the intestinal tissue into the intestine, and there are comparatively higher levels in the small intestine than the large intestine. E. coli specifically, wait until it has reached the low oxygen colon before it strikes.

E. coliThe most important asset is a small form of RNA that activates certain genes when oxygen levels are low enough, the researchers reveal. It is at this point that the infection really gets established. Thanks to this natural process of sensing, the bacteria are able to establish infection and begin producing harmful Shiga toxins.

The researchers believe that other bacterial pathogens, such as Shigella and Salmonella, probably uses a similar control mechanism, although more work needs to be done to determine it.

“If researchers can figure out how to block oxygen sensation, we might be able to prevent it E. coli from making proteins that allow it to stick to our gut, "Kendall said." This can be an effective strategy to cure infections and because we do not target growth or survival, E. coli may not develop drug resistance – it just doesn't know where it is. "

Kendall and Melson have published their findings in the scientific journal PNAS.

Health and balance of the gut microbiota is important in the development of bacterial infection

More information:
Elizabeth M. Melson et al. SRNA DicF integrates oxygen sensitivity to enhance enterohemorrhagic Escherichia colivirulence via distinctive RNA control mechanisms, Proceedings of the National Academy of Sciences (2019). DOI: 10.1073 / pnas.1902725116

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University of Virginia

E. coli secret weapons for causing the worst possible infection (2019, August 16)
retrieved August 16, 2019

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