What the Heck is an E. coli ?

 

What's going on, here?

Here we go again --- This "bug" simply refuses to disappear from the news. Every time you turn around anymore, there are warnings about hamburger meat (involving Hudson Foods and E. coli, or non-pasteurized apple juice and E. coli.
So, I thought it might be useful to find out just what an "E. coli" is, and why all the warnings. Before we start with the problems, it'll help to discuss some background, first.

What does E.coli mean?

E. coli is the abbreviated name of the bacterium in the Family Enterobacteriaceae named Escherichia (Genus) coli (Species). Dave Graham in the Department of Microbiology, University of Illinois at Urbana/Champaign, recently pointed me to information gleaned from G.W. Tannock's book, Normal Microflora,1995, Chapman & Hall, which reveals that approximately 0.1% of the total bacteria within an adult's intestines (on a Western diet) is represented by E. coli. Although, in a newborn infant's intestines E. coli, along with lactobacilli and enterococci represent the most abundant bacterial flora.

In fact, it is for this reason that the organisms which happily inhabit the intestinal tract as normal flora are named enteric bacteria. The Family to which E. coli belongs (Enterobacteriaceae, is named what it is - because of the Greek word enterikos - which pertains to the intestine. The name Escherichia comes from the name of the person Escherich, who in 1885 first isolated and characterized this bacterium.

I thought E.coli bacteria were OK....

You are correct, for the most part. The presence of E. coli and other kinds of bacteria within our intestines is necessary for us to develop and operate properly, and for us to remain healthy - E. coli, along with other species of bacteria, provide us with many necessary vitamins for example. The bacteria make the vitamins, and we gladly absorb them. We pretty much depend upon E. coli in our intestines for our source of Vitamin K and B-complex vitamins.

The fetus of any animal is completely sterile. Immediately after birth however, the newborn acquires all kinds of different bacteria which live symbiotically (we help them to live, and they help us to live) with the newborn and throughout the individual's life. From the day we are born, we are _never_ without bacteria. However, the helpful bacteria like these are located "only" in regions of our body directly exposed to the environment, e.g., our intestines, upper and lower respiratory tract, etc... and never within our bloodstream or the tissues inside our body. Sounds weird, but, it's true - billions of these little critters chugging away, making things we need, helping to digest our food, etc., -- very important to us and most of them are exceedingly kind to us - except when they become teenagers and enter the throes of puberty (just kidding). Indeed, animals who are born and raised "germ free", are really wimpy.... they have thin intestinal walls, puny heart output, and require lots of vitamin supplements just to stay alive.

So, when are E.coli bacteria bad for us?

Truly, you have billions of "friends" that you never knew you had. So, "What's the big deal about E. coli?" you ask with a puzzled expression on your face. Well, now I need to talk about the "bad guys." Bacteria are somewhat like humans in that certain individual humans are not very nice - and we know that some individual humans can be downright dangerous. Of course _all_ humans belong to the Genus/Species Homo sapiens, and _all_ E. coli belong to, well, Escherichia coli. So, as there exist individual humans, so too can different individuals exist among E. coli bacteria - we call such individuals a different "strain" of bacteria within a given species. Some of these different strains of bacteria (there may be several within a given species) can be harmful to us. Each of us - given the assumption that a human is reading this information - is sort of a strain of the human species, sapiens. We are different because we are genetically different, e.g., unless we are one member of an identical twin pair, the combination of genes each of us possess is different from every other human on the face of the earth - or arm of the earth for that matter. If you think about it a little bit, there are only about 5-billion (is that about right?) humans who are alive on the earth - there are probably that many bacteria in your intestine alone - don't worry - they don't take up much room.... So, it is possible for us to acquire an individual strain of E. coli which mixes with the other E. coli in our intestines. Now, since an individual strain of E. coli may exist, this situation means that this particular strain of E. coli is genetically different than the vast majority of E. coli in our intestines; otherwise, it would not be a different strain of this organism. If this E. coli strain happens to have genetic information for producing something harmful to us, then, we may be in trouble.

OK; who "is" the bad guy?

The rare strain of E. coli that is getting a lot of "press" lately because it is indeed a bad bug, is E. coli O157:H7, a member of the EHEC - enterohemorrhagic E. coli group. Enterohemorrhagic means an intestinally-related (here we are at the Greek word enterikos again) organism which causes hemorrhaging - and therefore, loss of blood. The image shown below is a picture of an electron microscope visualization (an electron micrograph) of O157:H7 (compliments of David Graham, University of Illinois at Urbana/Champaign). 

 

How then do we "pick up" this organism?

Basically, here is the problem: E.coli bacteria are everywhere in the environment. But, since they are such a common occupant of all animals, anytime we eat something, drink something, or touch our hands to something that has been either a part of or has been near where animals are, there is always the potential to ingest these bacteria - is a good reason for washing your hands now and then, huh?

How did this strain of E. coli come to be?

Since bacterial cells are all over the place, it is possible for them to acquire genetic information from other sources (bacterial viruses, plasmids, or just naked pieces of DNA floating around and about) - bacteria are "pretty good" at this - this information has nothing to do with the original genetic information necessary for the survival of the bacterium - although in some cases, acquisition of this information may provide an advantage for survival. In the case of E.coli O157:H7, a long-ago cell appears to have been infected with a bacterial virus. This particular virus had the ability to insert its own DNA into the bacteria's chromosome without harming the bacterium - and to remain there. Now, every time this bacterial cell divided, the virus DNA, being now a part of the bacterial DNA, was passed on to every daughter cell - and now, we have the E.coli strain, O157:H7.... This virus's genetic information (genes) unfortunately (for us) contained information for the production of a toxin, called Shiga-like toxin (SLT), or is sometimes called, Vero toxin. Consequently, this strain of E.coli, and all of its progeny produce this toxin. The toxin is a protein which causes severe damage to intestinal epithelial cells (the cells that line the wall of the intestine). The damage is so severe that if we acquire this bacterial strain, not only do we lose water and salts, blood vessels are damaged, and bleeding occurs - lots of bleeding - hemorrhaging. This condition is particularly dangerous to small children - may be lethal - children are too small to tolerate much blood and fluid loss. It is for this reason that small children should not be allowed to become dehydrated, even in mild cases of diarrhea. Too, in some cases another syndrome is involved which is called hemolytic uremic syndrome (HUS), which is characterized by kidney failure and loss of red blood cells. Approximately 5% to 10% of little kids progress to this stage of disease - which is very dangerous for them. In severe cases, the disease can cause permanent kidney damage. The presence of this bacterium can also be very dangerous to the elderly or infirm. There can be a combination of HUS and some other things which involve the blood system, which can be lethal to the elderly in 50% of the cases. So, E.coli O157:H7 is a dangerous organism, for sure.

Recent News:
1. As of August, 1997, various "lots" of hamburger meat produced for shipment by Hudson Foods were found to be contaminated with a harmful strain of E. coli. The strain of E. coli involved is again O157:H7. The Hudson Foods plant in Nebraska responsible for the contaminated beef is now closed. Approximately 25 million pounds of beef are being recalled - all of the beef shipped from this plant. And, all beef presently at the plant is being destroyed. If you wish, please examine the following links to recent and previous information about outbreaks of this organism.

a. U S Food & Drug Administration Center for Food Safety & Applied Nutrition; and

b. U S Food & Drug Administration Center for Food Safety & Applied Nutrition.

Please also see: Update. The updated release provides information about additional recalls of Hudson frozen beef, issued by the USDA. These articles also each provide all presently-known information regarding the Lot numbers of the meat shipments involved. Consumers are cautioned to re-examine any frozen ground beef they may have stored in their freezer to see if any of the identified Lot Numbers are present.

Interestingly, the USDA as no authority to force an industry to recall food which threatens the safety of the population in the US. The government can only recommend that the meat be recalled. The Secretary of Agriculture states that he is planning to see that Congress again consider legislation to increase the authority of the USDA - the arm of the Federal Government which is responsible for the safety of food products in the nation.

Past News:
During and after November, 1996, I am sure that you heard about the outbreak of O157:H7 E. coli in Canada, the Northwest and West (US). The outbreak has been traced to ingestion of a popular brand of non-pasteurized apple juice (Odwalla, Inc.). I believe that one 16 month-old child has died in Colorado as a result of the illness caused by this bacterium, and a fairly large number of people were made severely ill (40) in British Columbia, California, Colorado, and Washington. This brand of apple juice is distributed to: Washington, California, Oregon, Colorado, New Mexico, Nevada, Texas, Idaho, and British Columbia. As of November 12, 1996, there is a call for legislation which will require that all apple juice be pasteurized - just as milk is required to be pasteurized. Louis Pasteur developed a process whereby milk is treated with heat (63C for 30 minute - older method) to kill harmful bacteria ((will not kill spores), but nowadays milk and other pasteurized products produced in large quantities are often treated by a modification of the older method. This process, called flash pasteurization, involves exposure of milk and other liquid products to at least 72C (approx. 162F) for at least 15 seconds, with rapid cooling. Please see: Better Use a Pressure Cooker! for more information on the use of heat to kill harmful organisms. As of July 23, 1996, there had been about 8,000 cases of an EHEC strain affecting people in a city in Japan. According to an email contact from Mr. John Harrington in Osaka, who wrote: "The Ashahi Evening Newspaper (Wed., July 24 edition), [states that as of] Tuesday, 8444 people throughout Japan have developed O157-like symptoms. More than 6000 of them are in Sakai, a suburb of Osaka. The outbreak has now spread to 40 of 47 prefectures (the equivalent of US counties), and the number of victims seems to increase steadily at about 100 [per] day. Most recently, a 10 year old girl and a 85 year old woman died." From news reports it is my understanding that over 600 children have become infected, and almost 60 of them are in critical condition - with the uremic syndrome mentioned above. So far, the authorities cannot locate the source of the contamination - school lunches, they think. Unfortunately, when the outbreak among school children in Sakai initially occurred, the remaining lunches were destroyed - so - there are no samples from which to try to isolate the organism (locate the source of contamination). I do not know if this strain is O157:H7 - there are several different verotoxin-like expressing strains of E. coli, several of which have been identified in Japan... each numbered in a similar fashion. Hopefully, the Japanese health workers will be able to locate the source of the problem, and the children will be OK.
End News

What does all of this information have to do with hamburger meat, or other food products?

We'll talk about meat products first. Unless there is a cut in the meat, the meat below the surface is normally sterile (unless there is some intracellular organism present). However, whether or not some intracellular bug is around, the outside surfaces of all meat will have bacteria present - so - if some meat happens to be contaminated with the rare E.coli strain, O157:H7, it will be on the surface of the meat, and not down inside the fibers of the meat. However, as soon as the meat is cut with a knife or punctured with a fork, the knife blade or fork tine will carry the bacterial cells down into the cut or puncture - usually, such a situation is relatively safe because we cook the meat - certainly we cook the surface of the meat. Remember though, bacteria are _really_ small, so even a tiny, pretty much invisible cut in the meat could introduce bacteria down inside. In the case of E.coli O157:H7, the total number of bacteria required for infection appears to be about 10 - that's right, only 10 bacterial cells! Therefore, it is always safest to cook _all_ meat at least until the juices of the meat run absolutely clear - not pink - clear.

Now, if the meat is ground (we call it hamburger if it's ground beef) we have a much more risky situation because any bacterial cells originally only on the surface of the meat, will _now_ be distributed _throughout_ the preparation. It is _very_ important in this case to thoroughly cook the meat - until the juices run absolutely clear. Actually, the latest recommendation is that each hamburger pattie must reach an internal temperature of 160 degrees F. Apparently, viable (living) E. coli have been isolated from hamburger meat cooked to the point of "juices running clear". This procedure is very similar to that one would use to cook pork or perhaps a Thanksgiving turkey, e.g., observe the internal temperature of the meat before it is served.

Just remember, if you like your meat and especially hamburgers, "rare", you are taking a significant risk. It is also important to realize that meat may not be the only source of contamination with such bacteria or other dangerous bacteria - any contaminated water source or contaminated person can load these bacteria onto vegetables, etc. So, it is a good idea to be careful with everything - wash fresh fruit, vegetables, etc., thoroughly before eating. This last statement is very important, since as mentioned above, recent cases of O157:H7 infection have been found associated with non-pasteurized apple juice. This organism is apparently spreading around and about. So, it is important to be vigilant and aware.

What do I do if I or someone in my family gets sick after eating hamburger or something else - or for that matter, just gets sick?

No matter when, - if diarrhea occurs, always pay close attention to the symptoms... look for the presence of fever, vomiting, etc., particularly if the person is an infant, a small child, or an elderly or infirm adult. Look for any signs of blood in the stool. If you see anything that worries you, call your physician immediately - don't worry about the possibility of being mistaken and perhaps looking "silly." The organism is difficult to identify [recommended method is to use a genetic probe - associates with the toxin's(s) gene sequence(s)] - so - be as patient as possible - treatment will be given for the symptoms and treatment will be given to help rid the person of the infection.

How long does it take for any symptoms to appear?

Well, the answer to this question is a tough one. There are many things which may influence the onset of symptoms for this particular disease. Symptoms may appear within hours or may appear only after several days. It is for this reason that if diarrhea occurs, one should examine the stool for blood, and pay attention to any other symptoms which may occur, particularly if the person affected is a young child, is elderly, or is infirm in any way. The following are some of the things which can influence the time it takes for symptoms to occur:

(1) The actual number of organisms ingested - the higher the number ingested, the sooner the possibility for symptoms (the relatively greater concentration of toxin made).
(2) The health status of the individual - the weaker or less healthy, the sooner the possibility for symptoms.
(3) The individual's natural resistance to either (a) the growth of the organism within the intestine, or (b) the effect of the toxin itself. Different people may respond differently.

Usually, the disease is self-resolving (means that the disease clears "on its own") within about 8 days or so. However, as stated above, if any blood appears in the stool, or if watery diarrhea appears in an infant or a small child, one should immediately contact one's physician and describe the symptoms as accurately as possible. Whether or not E. coli O157:H7 is involved, diarrhea for any reason in a little kid can potentially be dangerous - so - discuss the symptoms with your physician if you are the least bit concerned.

How can I reduce the risk of infection from E.coli O157:H7?

  1. Always clean any surface that has come in contact with raw meat, before any other item is placed on that surface.
  2. Always thoroughly wash your hands after handling raw meat, and before you handle any other utensils or other food items.
  3. Never use the same plate, tray or utensils for the cooked meat that you use for the raw meat - unless you thoroughly wash the plate, tray or utensils in-between.
  4. Always cook meat, _especially_ ground meat, until the juices run absolutely clear - pink _is not_ good enough. In fact, it is necessary for the internal temperature of a hamburger pattie to reach 160 degrees F to kill all of any contaminating E. coli.
  5. In day-care centers, schools, etc., any small children with diarrhea should be carefully handled, and kept separate from all well children. All diapers, and any soiled clothing should be kept separate from all well children. The day-care worker, teacher, and health-care personnel should practice strict hygeine at all times, regardless of the health of the children.
The best advice is to of course be smart about all of this... realize that there is always a risk and simply take common-sense actions to minimize the risk.

Here is a link to the National Food Safety Database with all kinds of useful information about Food Safety. And, here are links to other pages with information on E. coli O157:H7, and other emerging strains of enterohemorrhagic E. coli. Please see: All About Beef from the USDA; Information from "The Bad Bug Book" provided by the FDA; and, An article on Hemolytic Uremic Syndrome in South Australia, and a link to the Centers for Disease Control and Prevention (CDC), Atlanta, Georgia: Centers for Disease Control.
 

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