How to protect yourself from E coli infection ?

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E. coli bacteria: what are they, where did they come from, and why are some so dangerous?

Escherichia coli (E. coli) are members of a large group of bacterial germs that inhabit the intestinal tract of humans and other warm-blooded animals (mammals, birds). Newborns have a sterile alimentary tract, which within two days becomes colonized with E. coli.  
More than 700 serotypes of E. coli have been identified.  The “O” and “H” antigens on their bodies and flagella distinguish the different E. coli serotypes, respectively.  The E. coli serotypes that are responsible for the numerous reports of outbreaks traced to the consumption of contaminated foods and beverages are those that produce Shiga toxin (Stx), so called because the toxin is virtually identical to that produced by another bacteria known as Shigella dysenteria type 1 (that also causes bloody diarrhea and hemolytic uremic syndrome [HUS] in emerging countries like Bangladesh) 


E. coli O157:H7—a foodborne pathogen
E. coli O157:H7 was first recognized as a foodborne pathogen in 1982 during an investigation into an outbreak of hemorrhagic colitis (bloody diarrhea) associated with the consumption of contaminated hamburgers (Riley, et al., 1983).  The following year, Shiga toxin (Stx), produced by the then little-known E. coli O157:H7, was identified as the real culprit. 
In the ten years following the 1982 outbreak, approximately thirty E. coli O157:H7 outbreaks were recorded in the United States (Griffin & Tauxe, 1991).

Sources of E. coli infection

E. coli O157:H7 bacteria and other pathogenic E. coli is believed to mostly live in the intestines of cattle (Elder, et al., 2000) but has also been found in the intestines of chickens, deer, sheep, and pigs. 


E. coli can be transmitted from several sources:
Food

Water

Animals

Humans

E. coli in Fresh Fruits and Vegetables
Fruit that comes in contact with animal, especially cattle, feces, (as might happen if fruit has fallen and is harvested/picked from/off the ground), can also transmit Stx-producing E. coli. 

Fresh vegetables can become contaminated pre- or post-harvest.  Contaminated seeds, irrigation water, and flooding have contributed to E. coli outbreaks traced to sprouts, lettuce, spinach, parsley, and other fresh produce

Symptoms of E. coli infection
What happens after the Shiga toxin-producing E. coli are ingested?
E. coli infection occurs when a person ingests Shiga toxin (Stx)-producing E. coli (e.g., E. coli O157:H7) after exposure to contaminated food, beverages, water, animals, or other persons.  After ingestion, E. coli bacteria rapidly multiply in the large intestine and bind tightly to cells in the intestinal lining.  This snug attachment facilitates absorption of the toxin into the small capillaries within the bowel wall, where it attaches to globotriaosylceramide (Gb3) receptors. 
Inflammation caused by the toxins is believed to be the cause of hemorrhagic colitis, the first symptom of E. coli infection, which is characterized by the sudden onset of abdominal pain and severe cramps, followed within 24 hours by diarrhea .  Hemorrhagic colitis typically occurs within 2 to 5 days of ingestion of E. coli, but the incubation period, or time between the ingestion of E. coli bacteria and the onset of illness, may be as broad as 1 to 10 days. 


As the infection progresses, diarrhea becomes watery and then may become grossly bloody, that is, bloody to the naked eye.  E. coli symptoms also may include vomiting and fever, although fever is an uncommon symptom. 
On rare occasions, E. coli infection can cause bowel necrosis (tissue death) and perforation without progressing to hemolytic uremic syndrome (HUS)—a complication of E. coli infection that is now recognized as the most common cause of acute kidney failure in infants and young children.  In about 10 percent of E. coli cases, the Shiga toxin attachment to Gb3 receptors results in HUS. 


Organ injury is primarily a function of Gb3 receptor location and density.  These receptors are probably always in the gut wall and kidneys, but heterogeneously distributed in the other major body organs.  This may be the reason that some patients develop injury in other vital organs (e.g., brain, etc).  Once Stx attaches to receptors, it moves into the cells’ cytoplasm where it shuts down the cells’ protein machinery resulting in cellular injury or death, and subsequent damage to vital organs such as the kidney, pancreas, and brain. 

Treatment for E. coli infection

Treatment for an E. coli Infection

In most infected individuals, symptoms of E. coli infection last about a week and resolve without any long-term problems.  Antibiotics do not improve the illness, and some medical researchers believe that these medications can increase the risk of developing post-diarrheal hemolytic uremic syndrome (D+HUS) (Wong, Jelacic, & Tarr, 2000).  Therefore, apart from good supportive care such as close attention to hydration and nutrition, there is no specific therapy to halt E. coli symptoms.  The recent finding that E. coli O157:H7 initially greatly speeds up blood coagulation may lead to future medical therapies that could forestall the most serious consequences (Chandler, et al., 2002).  Most individuals who do not develop D+HUS recover within two weeks. 


Treatment for those who develop HUS ranges from mild to very intensive.  Children are generally in the hospital for about two weeks (range 3 days to 3 months), and adults longer, as their courses tends to be more severe.  Since there is no way to end D+HUS, supportive therapy, including meticulous attention to fluid and electrolyte balance, is the cornerstone of survival. 

Preventing E. coli Infection

What can we do to protect our families from E. coli?

Since there is no fail-safe food safety program, consumers need to “drive defensively” as they navigate from the market to the table.  It is no longer sufficient to take precautions only with ground beef and hamburgers, anything ingested by family members can be a vehicle for infection.  Shiga toxin-producing E. coli are now so widely disseminated that a wide variety of foods can be contaminated.  Direct animal-to-person and person-to-person transmission is not uncommon.  Following are steps you can take to protect your family from E. coli.  

1. Practice meticulous personal hygiene.  This is true not only for family members (and guests), but for anyone interfacing with the food supply chain.  Remember that E. coli bacteria are very hardy (e.g., can survive on surfaces for weeks) and that only a few are sufficient to induce serious illness.  Since there is no practical way of policing the hygiene of food service workers, it is important to check with local departments of health in order to identify any restaurants that have been given citations or warnings.  The emerging practice of providing sanitation “report cards” for public display is a step in the right direction.
2. Be careful to avoid cross contamination when preparing and cooking food, especially if beef is being served.  This requires being very mindful of the surfaces (especially cutting boards) and the utensils used during meal preparation that have come in contact with uncooked beef and other meats.  This even means that utensils used to transport raw meat to the cooking surfaces should not be the same that are later used to remove the cooked meat (or other foodstuffs) from the cooking surfaces.
3. Do not allow children to share bath water with anyone who has any signs of diarrhea or “stomach flu”.  And keep any toddlers still in diapers out of all bodies of water (especially wading and swimming pools).
4. Do not let any family members touch or pet farm animals.  Merely cleaning the hands with germ “killing” wipes may not be adequate!
5. Wear disposable gloves when changing the diapers of any child with any type of diarrhea.  Remember that E. coli O157:H7 diarrhea initially is non-bloody, but still very infectious.  If gloves are not available, then thorough hand washing is a must.
6. Remember that achieving a brown color when cooking hamburgers does not guarantee that E. coli bacteria have been killed.  This is especially true for patties that have been frozen.  Verifying a core temperature of at least 160 degrees Fahrenheit for at least 15 seconds is trustworthy.  Small, disposable meat thermometers are available, a small investment compared to the medical expense (and grief) of one infected family member.
7. Avoid drinking (and even playing in) any non-chlorinated water.  There is an added risk if the water (well, irrigation water or creek/river) is close to, or downstream from any livestock.

Irradiation offers the most practical and effective way of sterilizing foods and protecting the consumer.  It is already being used for poultry, and is approved for all other foods.  Even though the word “irradiation” conjures up fears of radiation exposure, irradiated food does not become “radioactive”; it is safe, and does not change the taste or texture of food.  To insure safety the public needs to be educated and the food industry convinced that this will not only protect the consumer, but also will also favorably affect their bottom line.  This should be a “no-brainer” given the fact that contaminated foods are costing the food industry hundreds of millions of dollars a year (recently, one beef processing company declared bankruptcy following a massive recall of contaminated hamburgers).  If this doesn’t work, the food industry may be required to implement this or other equally effective measures.