Study Reveals E.Coli's Grip on Gut
Finding might aid illness prevention, treatment, researchers say
THURSDAY, Oct. 18, 2007 (HealthDay News) -- U.S. scientists have discovered how a potentially deadly form of E. coli bacteria adheres to and colonizes the gut.
Enterohemorrhagic Escherichia coli O157:H7A, or E. coli, is a common cause of food poisoning.
The authors of the study hope the breakthrough will one day help with disease prevention strategies. But others say breakthroughs like that are still far off.
"The study was conducted in vitro, not in an animal model, human or otherwise," noted Dr. Pascal James Imperato, distinguished service professor and chair of the department of preventive medicine and community health at the State University of New York Downstate Medical Center in New York City. "Whether this in vitro result is reflective of what happens in vivo [in the gut] remains to be demonstrated."
There are several strains of E. coli and one in particular, E. Coli 0157:H7, can be deadly.
Human infections most often result from eating uncooked ground beef, because cattle carry the pathogen in their intestines without getting sick. E. coli can also be acquired from consuming contaminated dairy products, vegetables, unpasteurized juice, through person-to-person contact and through either swimming in or drinking water contaminated with sewage.
Infection with E. coli 0157:H7 can result in abdominal cramps and bloody diarrhea and, less commonly, a condition called hemolytic uremic syndrome (HUS), which is characterized by anemia and kidney failure and can end in death.
The U.S. Centers for Disease Control and Prevention estimate that 73,000 infections and 61 deaths are attributable to E. coli 0157:H7 each year. The very young and the very old are particularly prone to developing life-threatening HUS.
For this study, the researchers at the University of Arizona, Tucson, found that several proteins bind together to form a structure known as an adhesive type IV pilus, that they call hemorrhagic coli pilus (HCP). This HCP bundle allows the bacteria to attach to human intestinal epithelial cells, the researchers said.
The authors also found that individuals with HUS had an immune response to one component of HCP.
The research group is now looking to start experiments in animals and/or humans. "In our lab, we did in vitro experiments, but we are trying some collaboration with other universities to do some in vivo [in animals/humans] experiments," said Partha Samadder, a postdoctoral fellow in the lab of Jorge A. Giron, the study's lead author.
"Overall, it all has to be corroborated by others," Imperato said. "All that said, meaningful therapeutic interventions to prevent this cascade of molecular biological events will be years off. Meanwhile, the key is to prevent these infections in the first place."
There are ways to help prevent foodborne illness. They include:
- Make sure ground beef and other meats as well as eggs are well cooked before you eat them.
- Wash raw fruits and vegetables with soap. Pay particular attention to leafy greens as there are lots of crevasses and cracks where E. coli can hide.
- Don't chop vegetables on the same block where you just made beef hamburgers or prepared other meat. Keep raw meat separate from ready-to-eat foods.
- Keep raw and ready-to-eat foods completely separate.
- Refrigerate leftovers promptly.
- Avoid bruised produce such as tomatoes.
- Make sure all cooking utensils including meat thermometers and cutting boards are thoroughly cleaned with soap and hot water after you've handled them.
- Wash your hands regularly with soap and hot water.
- Drink only pasteurized milk, juice or cider.
- Drink municipal water that has been treated with chlorine or another disinfectant.
There's more on E. coli at the U.S. Centers for Disease Control and Prevention.