A pair of scientists at the University of Virginia School of Medicine revealed how E. coli looks for the most oxygen-free cracks in the colon to cause the worst possible infection.
The new discovery shows how the foodborne pathogen knows where and when to begin colon colonization on its path to becoming ill. Recognizing the low oxygen environment of the large intestine, a dangerous bacterium gives the best chance of finding a strong infection – one that is harmful to the host.
"Bacterial pathogens typically colonize specific tissue in the host," said researcher Melissa Kendall of the UVA's Department of Microbiology, Immunology and Cancer Biology. "Therefore, as part of their infection strategies, bacterial pathogens accurately deploy the timing of proteins and toxins in these specific colonization niches in the human host. This allows pathogens to conserve energy and avoid detection by our immune system and ultimately cause disease.
"Knowing how bacterial pathogens sense where they are in the body, one day we can prevent E. coli, as well as other pathogens, from knowing where it is inside the human host and allowing it to pass through the body without causing infection. "
E. coli naturally lives in our columns and most strains do us no harm. But there are several strains that can cause cramps, diarrhea, vomiting, even kidney failure and death. Children are at particular risk. As such, E. coli outbreaks appear in the news periodically. For example, in July, people in several states became ill with E. coli associated with ground buffalo meat
Kendall and graduate student Elizabeth M. Melson shed important light on how harmful they are E. coli infections are detected in the body. Researchers have outlined a process that bacteria use to detect low levels of oxygen in the colon and then produce proteins that allow E. coli attach to the host cells and detect infection.
Oxygen actually diffuses from the intestinal tissue into the intestine and has relatively higher levels in the small intestine than the large ones. E. coli specifically waits until it has reached the low oxygen level of the colon before it hits.
E. coliThe vital asset is a small form of RNA that activates certain genes when oxygen levels are low enough, the researchers found. At this point, the infection is really getting established. Thanks to this natural sensing process, the bacteria are able to detect infection and begin to produce harmful toxins from Shiga.
The researchers believe that other bacterial pathogens, such as Shigella and salmonellathey probably use a similar control mechanism, though more work needs to be done to establish this.
"If scientists can figure out how to block oxygen uptake, we can prevent E. coli by making proteins that allow it to adhere to our intestines, ”Kendall said. – This can be an effective strategy to curb the infection and since we are not aiming for growth or survival, E. coli it 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 are important for the progression of bacterial infection
Elizabeth M. Melson et al. SRNA DicF integrates oxygen sensors for enhancing Escherichia enterohaemorrhagic colliery by distinctive RNA control mechanisms Proceedings of the National Academy of Sciences (2019). Doi: 10.1073 / pnas.1902725116
E. coli's secret weapon for causing the worst possible infection (2019, August 16)
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