E. coli thrives with help of bacteria.

• Position: Intestinal Disorders

A strain of E. coli that causes severe, sometimes deadly, intestinal problems relies on signals from beneficial human bacteria and a stress hormone to infect human cells, a researcher at the University of Texas Southwestern Medical Center at Dallas has discovered. The finding could lead to the development of beta-blockers as a therapy to impede this cellular signaling system, causing the harmful bacteria to pass blindly through the digestive tract, according to Vanessa Sperandio, assistant professor of microbiology.

"You're not really attacking the bacteria per se," she says. "You are just rendering it blind. The bacteria won't activate the virulent genes unless it knows where it is. If it can't activate the things it needs to bind to the intestine, it will be washed away."

In the past, beta-blockers have been used to treat migraines, high blood pressure, glaucoma, and tremors, but not to impede disease. Developing new therapies for infection with this strain of E. coli--known as enterohemorrhagic Escherichia coli, or EHEC--is important because treatment with conventional antibiotics can cause the release of more toxins and may worsen the disease outcome. Sperandio found that when a person ingests EHEC, the bacteria travel blindly through the digestive tract until reaching the intestine, where friendly bacterial flora and the hormone epinephrine, or adrenaline, send cellular signals alerting the bacteria to its location. This cellular cross talk leads to a cascade of genetic activations in which the EHEC colonizes the intestine and translocates toxins into human cells...