Escherichia coli


The latest food poisoning of E.Coli makes one wonder: Just how safe is our food supply? Are the increased frequency of incidents an indicator of sloppy food handling, processing, and transport, or are we seeing the work of some group or entity testing our ability to detect pathogens in our food supply?

Contaminating foods with E. Coli is extraordinarily easy. Just culture it in an easily made bilogical medium known as Agar. Agar is typically sold as packaged strips of washed and dried seaweed, or in powdered form. Combine the E Coli culture with liquid, and spray a field with a hand pump, or toss a jar of it onto a bin of it during harvesting or processing.

The culprit here is a speciifc strain of Escherichia coli (usually abbreviated to E. coli, coli is Latin for “of the colon”) discovered by Theodor Escherich, a German pediatrician and bacteriologist, is one of the main species of bacteria that live in the lower intestines of mammals, known as gut flora. Specimens have also been located on the edge of hot springs. Presence in surface water is a common indicator of fecal contamination. It belongs among the Enterobacteriaceae, and is commonly used as a model organism for bacteria in general. One of the root words of the family’s scientific name, “enteric”, refers to the intestine, and is often used synonymously with “fecal”.

The number of individual E. coli bacteria in the feces that a human excretes in one day averages between 100 billion and 10 trillion. All the different kinds of fecal coli bacteria, and all the very similar bacteria that live in the ground (in soil or decaying plants, of which the most common is Enterobacter aerogenes), are grouped together under the name coliform bacteria.

E.coli O157:H7 is the strain that cuases illness in humans and can be fatal, as has been the case this week with scallions served in food at Taco Bell Restaurants.

Escherichia coli O157:H7 is a leading cause of foodborne illness. Based on a 1999 estimate, 73,000 cases of infection and 61 deaths occur in the United States each year. In the ten CDC Foodborne Diseases Active Surveillance Network (FoodNet) sites (which represent 15% of the US population), there was a 29% decline in E. coli O157:H7 infection since 1996-98.

Infection with E. coli often leads to bloody diarrhea, and occasionally to kidney failure. People can become infected with E.coli O157:H7 in a variety of ways. Though most illness has been associated with eating undercooked, contaminated ground beef, people have also become ill from eating contaminated bean sprouts or fresh leafy vegetables such as lettuce and spinach. Person-to-person contact in families and child care centers is also a known mode of transmission. In addition, infection can occur after drinking raw milk and after swimming in or drinking sewage-contaminated water.

Consumers can prevent E. coli O157:H7 infection by thoroughly cooking ground beef, avoiding unpasteurized milk, and by washing hands carefully before preparing or eating food. Fruits and vegetables should be washed well, but washing may not remove all contamination. Public service announcements on television, radio, or in the newspapers will advise you which foods to avoid in the event of an outbreak.

Surprisingly, a common household spice, cinnamon, seems to kill this strain of E.Coli. When cinnamon is in, Escherichia coli O157:H7 is out. That’s what researchers at Kansas State University discovered in laboratory tests with cinnamon and apple juice heavily tainted with the bacteria. Presented at the Institute of Food Technologists’ 1999 Annual Meeting in Chicago on July 27, the study findings revealed that cinnamon is a lethal weapon against E. coli O157:H7 and may be able to help control it in unpasteurized juices.

Lead researcher Erdogan Ceylan, M.S., reported that in apple juice samples inoculated with about one million E. coli O157:H7 bacteria, about one teaspoon (0.3 percent) of cinnamon killed 99.5 percent of the bacteria in three days at room temperature (25 C). When the same amount of cinnamon was combined with either 0.1 percent sodium benzoate or potassium sorbate, preservatives approved by the Food and Drug Administration, the E. coli were knocked out to an undetectable level.

Let’s hope the active agent in cinnamon can be isolated and put twoards protecting our food supply.

In the meatime here is some information from the Center for Disiease Control

How is E. coli O157:H7 infection diagnosed?

Infection with E. coli O157:H7 is diagnosed by detecting the bacterium in the stool. About one-third of laboratories that culture stool still do not test for E. coli O157:H7, so it is important to request that the stool specimen be tested on sorbitol-MacConkey (SMAC) agar for this organism. All persons who suddenly have diarrhea with blood should get their stool tested for E. coli O157:H7.

How is the illness treated?

Most people recover without antibiotics or other specific treatment within 5 to 10 days. Antibiotics should not be used to treat this infection. There is no evidence that antibiotics improve the course of disease, and it is thought that treatment with some antibiotics could lead to kidney complications. Antidiarrheal agents, such as loperamide (Imodium®), should also be avoided.

In some people, E. coli O157:H7 infection can cause a complication called hemolytic uremic syndrome (HUS), a life-threatening condition that is usually treated in an intensive care unit. Blood transfusions and kidney dialysis are often required. With intensive care, the death rate for hemolytic uremic syndrome is 3%-5%.

What are the long-term consequences of infection?

Persons who only have diarrhea usually recover completely.

A small proportion of persons with hemolytic uremic syndrome (HUS) have immediate complications with lifelong implications, such as blindness, paralysis, persistent kidney failure, and the effects of having part of their bowel removed. Many persons with hemolytic uremic syndrome have mild abnormalities in kidney function many years later.

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December 11, 2006 11:32 am

Just thinking out loud, but I wonder if chemistry to attack germs and bacteria might be the wrong track? It seems to be a losing battle.
Perhaps we should be developing a way to enhance our natural immune system to resist bacteria and germs before they ever do us any damage?
Genetics could be a key part of the answer here, not antibiotics.
Any thoughts?

Anthony Watts
December 11, 2006 1:51 pm

Well Jack, genetics would be a technique that would outwit the bugs for a much longer period of time, perhaps even a century or two. But in the process we change ourselves because our genetic makeup is altered. The “Law of Unintended Consequences” may apply here. So any genetic solution would have to be done with the utmost caution.
Antibiotics work by degrading and bursting the cell wall of Gram positive type bacteria. They can build up immunity just like cockroaches can to Raid spray.
Perhaps a better solution to human disease may come in the form of nanotechnology.
One possible scenario: Microscopic robots that are designed to seek out and destroy certain cells, then self desctruct themselves after a period of time, and be flushed from the body as waste just like other dead cells.

Jack Lee
December 14, 2006 11:27 am

I want my grandson to read your articles.
I’ve heard that engaging frequently in stimulating thought reduces the odds for alzhiemers or the onset of age related dementia. In that sense, your scientific articles are good for the brain as opposed to mine which some people claim just gives them a headache! lol
Keep up the great work Anthony.
*** Moderator reply ***
Thanks Jack for the kind words

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