More on Prevention, Better Treatment for Infection Possible
Prevention, Better Treatment for Infection Possible
(Jun 28, 2006)
-- New research revealed this week may lead to improved treatment and prevention of some bacterial infections.
Scientists at the University of Texas Southwestern Medical Center at Dallas have identified a receptor, QseC, that the Escherichia coli (or E. coli) bacterium uses to receive signals from hormones in the intestine and subsequently transmit the bacteria into the intestine to cause infection and symptoms such as diarrhea.
The UT Southwestern researchers are the first to identify the QseC receptor. Their research was published in the Proceedings of the National Academy of Sciences.
Substance Found to Block QseC Receptor
Once the infection-releasing receptor was identified, the researchers were then able to block the signals sent from the intestine using phentolamine, an alpha blocker medication commonly prescribed to control high blood pressure.
"This [QseC] receptor is found in many pathogens [infection-causing bacteria or viruses], so we can use this knowledge to design specific antagonists to block bacterial infections," says study author Dr. Vanessa Sperandio, assistant professor of microbiology at the university.
The researchers studied the effect of adrenergic antagonists - including alpha and beta blockers (adrenaline-blocking medications) - on the QseC receptor's capacity to receive signals from the hormones in the intestine.
Phentolamine was successful in adhering to the receptor and filling the space that it would normally fill with the epinephrine and norepinephrine, hormones which are secreted in response to stress.
Further Study Planned
This knowledge opens the door to further understanding of the signaling processes between microbes and humans and to the development of novel treatments of bacterial infections with antagonists to these signals, Dr. Sperandio says.
New therapies are important because treating some bacterial infections with conventional antibiotics can cause the release of more toxins, which can damage vital organs and worsen disease outcome.
That importance is magnified because QseC is also found in other types of bacteria, including Shigella, which causes dysentery; Salmonella, which causes food poisoning and gastroenteritis; and Yersinia, which causes bubonic plague.
These are all emerging infectious diseases that afflict thousands of people each year in the US and worldwide, according to the Centers for Disease Control and Prevention (CDC).
Prior research by Dr. Sperandio found that when a person ingests the more virulent enterohemorrhagic E coli, or EHEC - which is usually transmitted through contaminated food such as raw meat - it travels peacefully through the digestive tract until reaching the intestine.
There, however, chemicals produced by the friendly gastrointestinal bacteria and the human hormones epinephrine and norepinephrine alert the E. coli bacteria to its location.
This cellular cross talk triggers a cascade of genetic activations prompting EHEC to colonize and translocate toxins into cells, altering the makeup of the cells and robbing the body of nutrients.
An infected person may develop bloody diarrhea or even hemolytic uremic syndrome, which can cause death in immune-weakened people, the elderly and young children.
The findings from this new study may provide better insight into future treatments for bacterial infections without the use of antibiotics, the researchers say.
"Overuse of antibiotics has led bacteria to develop resistance to antibiotics, so a novel type of therapy is needed," Dr. Sperandio says.
Always consult your physician for more information.
For more information on health and wellness, please visit health information modules on this Web site.
Facts About E. coli
There are hundreds of strains of the bacteria E. coli. Most strains of E. coli are harmless and live in the intestines of healthy humans and animals.
E. coli O157:H7, however, produces a powerful toxin that can cause a severe infection. (The combination of letters and numbers in the name of the bacterium refers to the specific markers found on its surface and distinguishes it from other types of E. coli.)
An estimated 73,000 cases of E. coli infection occur in the United States each year. The Centers for Disease Control and Prevention (CDC) recognizes E. coli as an emerging food-borne illness.
How is the E. coli infection spread?
Most E. coli illnesses have been associated with eating undercooked, contaminated ground beef. E. coli bacteria live in the intestines of healthy cattle and, although the number of organisms required to cause disease is not known, it is suspected to be very small.
Meat becomes contaminated during slaughter, and organisms can be thoroughly mixed into beef when it is ground. Contaminated beef looks and smells normal.
Other ways to transmit E. coli include:
Person-to-person contact in families and in child-care and other institutional-care centers can also be places where the transmission of the bacteria can occur.
Bacteria present on a cow's udders, or on equipment, may get into raw milk causing the infection.
Infection may occur after swimming in or drinking sewage-contaminated water.
It has been confirmed that unpasteurized juices, such as apple cider, may also cause the infection.
An E. coli infection can make a person very ill. The following are some of the most common symptoms associated with E. coli. Symptoms may include:
severe bloody diarrhea or non-bloody diarrhea
severe abdominal cramps
However, each individual may experience symptoms differently, and some individuals may have no symptoms at all.
The symptoms of an E. coli infection may resemble other medical conditions. Always consult your physician for more information.
(Our Organization is not responsible for the content of Internet sites.)