In the study, available online and in an upcoming issue of the Proceedings of the National Academy of Sciences, researchers interfered with a genetic sensing mechanism that allows the E. coli strain known as enterohemorrhagic O157:H7, or EHEC, to form colonies within cattle, causing the bacteria to die off before they could reach the animals' recto-anal junction, the primary site of colonization. Most other strains of E coli gather in the colon.
"We're diminishing colonization by not letting EHEC go where it needs to go efficiently," said Dr. Vanessa Sperandio, associate professor of microbiology and biochemistry at UT Southwestern and senior author of the study. "If we can find a way to prevent these bacteria from ever colonizing in cattle, it's possible that we can have a real impact on human disease.
"This could be something as simple as including some sort of antagonist in cattle feed, which would result in less shedding of the bacteria in fecal matter with less contamination down the road in food products."
Dr. Sperandio said the finding is important because an estimated 70 percent to 80 percent of the cattle herds in the U.S. carry EHEC.
Although EHEC can be a deadly pathogen to humans, the bacterium is part of cattle's normal gastrointestinal flora. EHEC harbors a gene called sdiA, which makes the SdiA protein. The SdiA protein senses a chemical made by microbes in the animal's rumen, the first of a cow's four stomachs, which serves as a large fermentation chamber. Detecting this signal allows EHEC to pass through the rumen and colonize the recto-anal junction.
For the study, the researchers injected two types of EHEC into the rumens of eight grain-fed adult cows. One mutant version lacked SdiA and could not detect the signal in the rumen. Another strain produced an enzyme that destroyed the chemicals in the rumen sensed by SdiA.
The researchers found that colonization diminished significantly when these EHEC strains were unable to sense the rumen chemicals. The process prevented the bacteria from moving on through the stomach and colonizing.
"If there's no signal, then there's no acid resistance, a requirement for the pathogen to make it to the recto-anal junction," Dr. Sperandio said. "Everybody had thought that this type of signaling occurred naturally in the gastrointestinal tract of mammals. Our finding serves as a proof-of-principle that we might be able to target this system to prevent food contamination."
EHEC, like other E coli strains, is usually transmitted through contaminated food. Recent outbreaks in the U.S. have been found in ground beef, spinach and raw sprouts. EHEC is responsible for outbreaks throughout the world of bloody diarrhea and hemolytic uremic syndrome – a condition that can lead to renal failure and death. Severe symptoms are most common in children, the elderly and immune-suppressed people.
Cattle are the primary source for most E coli infections in the U.S. When cattle waste reaches water sources near food crops, contamination can occur. Unsanitary slaughtering of cattle also can lead to cross-contamination of the beef itself, and shipment of infected food speeds the rate at which the public can become ill.
Dr. Sperandio said the next step is to assess what happens to cows fed a grass-based, rather than grain-based, diet.
Other UT Southwestern researchers involved in the study were Dr. Darya Terekhova, postdoctoral researcher in microbiology; and Dr. David Hughes, lead author and former graduate student in microbiology. Dr. Hughes is now at the University of Miami.
Researchers from the University of Idaho, UT Dallas, the USDA Agricultural Research Service and the University of Maryland School of Medicine also contributed to the study.
The study was funded by the National Institutes of Health, Burroughs Wellcome Fund, and the National Cattlemen's Beef Association.
This news release is available on our World Wide Web home page at www.utsouthwestern.edu/home/news/index.html
To automatically receive news releases from UT Southwestern via e-mail, subscribe at www.utsouthwestern.edu/receivenews
Kristen Holland Shear | EurekAlert!
Observing the cell's protein factories during self-assembly
15.06.2018 | Charité - Universitätsmedizin Berlin
Scientists unravel molecular mechanisms of Parkinson's disease
13.06.2018 | The Francis Crick Institute
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...
Water molecules exist in two different forms with almost identical physical properties. For the first time, researchers have succeeded in separating the two forms to show that they can exhibit different chemical reactivities. These results were reported by researchers from the University of Basel and their colleagues in Hamburg in the scientific journal Nature Communications.
From a chemical perspective, water is a molecule in which a single oxygen atom is linked to two hydrogen atoms. It is less well known that water exists in two...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
15.06.2018 | Materials Sciences
15.06.2018 | Ecology, The Environment and Conservation
15.06.2018 | Power and Electrical Engineering