E. coli (or Escherichia coli) is a type of bacteria with hundreds of different strains. Some of the strains produce a powerful poison that can cause severe illness. The strains are differentiated from one another based on specific markers found on its surface.
ARE ALL STRAINS OF E. COLI HARMFUL?
No. Most strains of E. coli are actually harmless and live in the intestines of healthy individuals, including animals. The intestine is a tube shaped structure that is part of the digestive tract.
WHAT DOES E. COLI LOOK LIKE?
A picture of E. coli under a microscope is shown below. The tiny, hair-like structures you see help the bacteria attach itself to the surfaces inside the body, such as the lining of the intestines.
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HOW DO PEOPLE GET SICK FROM E. COLI?
People usually get sick from E. coli when the harmful strains of this bacteria are not killed during the cooking process, as the bacteria is found in many uncooked foods. Normally, cooking kills the bacteria. However, undercooked food such as ground beef, can cause E. coli infection. E. coli can be spread by eating other foods that have not been properly cleaned. Examples of such foods include salami, lettuce and some other fresh produce, alfalfa and radish sprouts, and fruit juice.
But how do harmful strains of E. coli get into the meat in the first place you ask. What typically happens is that the harmful strain of E. coli live in the intestines of cows. The meat can become contaminated during the slaughtering process, which then gets into the ground beef. It is difficult to detect and prevent E. coli contamination since the bacteria does not have an abnormal smell or appearance and since only small numbers are needed to cause infection.
Meat is not the only way people can get E. coli infection. E. coli can be present on the udders of cows or on dairy farming machinery, allowing it to possibly contaminate raw milk. Thus, drinking unpasteurized milk products increases the risk of E. coli infection. All effort should be made to drink pasteurized milk to minimize the risk of E. coli infection. Pasteurization is a process in which is used to destroy harmful products in perishable food products without harming the food itself. Unpastuerized apple cider is another type of drink that can spread E. coli.
Another way E. coli spreads is when a person comes in contact with the feces of an infected individual. This can happen in child care facilities, hospital settings, and even in one’s own home. Although you may wonder how you would come in contact with someone’s feces in your home, it is actually fairly easy and may happen without you knowing it. What usually happens is that an infected person does not wipe him/herself properly or not wash his/her hands after wiping. The person then touches household items, such as the refrigerator door. An uninfected person later opens the refrigerator door, touches E.coli without knowing it, bites his/her fingernails, and gets infected.
Toddlers who are not potty trained are also likely to spread the infection after having “accidents” that require changing of undergarments. If caretakers do not wash their hands properly after changing a diaper, that can also cause the infection to spread. Another source of infection can be swimming water or improperly treated drinking water that has been contaminated by human or animal feces containing E. coli.
WHERE ARE SIGNS AND SYMPTOMS OF E. COLI INFECTION?
Signs and symptoms of E. coli infection include severe and sometimes bloody diarrhea and stomach cramps. A mild fever may also occur. Symptoms may last for about 5 to 10 days. Although older children rarely carry the disease without symptoms, smaller children may continue to excrete the poison made by E. coli weeks after recovery.
There are some cases in which a serious condition known as hemolytic-uremic syndrome can occur as a result of E. coli infection. This condition causes red blood cell death and kidney failure. Red blood cells help carry oxygen in the blood. The kidneys are two organs located on each side of the spine, behind the stomach that filter wastes from the blood.
People who are most likely to develop hemolytic-uremic syndrome are older people, people with weakened immune (defense) systems, and children younger than age five. Hemolytic-uremic syndrome is the main cause of sudden kidney failure in children and most cases are caused by E. coli.
HOW IS E. COLI DIAGNOSED?
To diagnose E. coli, a sample of the feces is analyzed. This is known as a stool sample, since another word for feces is stool. The specific name of the test that is used to detect E. coli in a stool sample is called a SMAC agar. SMC stands for sorbitol MacConkey. Sorbitol is a type of sugar used in the test. Agar is a jelly-like material derived from algae (plant-like water organisms) that is often used as a substance to test for the presence of bacteria. The word “MacConkey” comes from Alfred MacConkey, a British bacteriologist (1861-1931) who developed easy ways to culture (grow) certain types of bacteria.
HOW IS E. COLI TREATED?
In many cases, E. coli does not require treatment, since diarrhea (often the only sign of infection) goes away in about one week. Unfortunately, antibiotic treatment has not been helpful in treating E. coli and is some cases, can actually bring on kidney failure. Although some may be tempted to use medications to stop diarrhea, this is usually not a good idea since it would keep E. coli inside the body instead of letting it leave. As always, consult your doctor for advice specific to your medical situation.
In cases of hemolytic-uremic syndrome (see above), the patient will be admitted to the Intensive Care Unit (ICU). An ICU is an area of a hospital in which patients with life threatening medical problems of sudden onset are placed for close monitoring and constant, complicated, detailed nursing and medical care. In the case of hemolytic-uremic syndrome, the patient will require a blood transfusion, in which blood from another person is used to replace the diseased blood.
Kidney dialysis may also be required in patients with hemolytic-uremic syndrome. Dialysis is a technique in which one is hooked up to a machine that performs the functions of the kidneys, removing wastes and extra water from the blood. Although long-term dialysis may be required in some cases and abnormal kidney function can continue for many years, people usually survive the complication of hemolytic-uremic syndrome. Those who recover from this syndrome often have life-long medical complications such as seizures, paralysis, high blood pressure, and blindness.
In some cases, E. coli infection may cause such damage to the intestine that the colon needs to be removed. The colon is the major part of the large intestine, located in the belly. Removal of the colon is major surgery that may cause life-long diarrhea.
CAN E. COLI INFECTION BE PREVENTED?
There are steps that can be taken to reduce E. coli infection. One way is to avoid eating meat, but that is not an option many people want to choose. If eating meat is something you enjoy, doctors recommend using a meat thermometer to make sure the meat is well-done. The internal temperature should be 155 degrees Fahrenheit. All effort should be made to drink pasteurized milk to minimize the risk of E. coli infection. Pasteurization is a process in which is heat is used to destroy harmful products in perishable food products without harming the food itself.
WHEN WAS E. COLI FIRST DISCOVERED?
E. coli was first discovered in the United States in 1982 as a form of food poisoning. This occurred when a bunch of hamburgers contaminated with E. coli caused an outbreak of illnesses characterized by severe, bloody diarrhea. The deadliest outbreak, however, occurred in Scotland in 1996-1997, where it killed 21 people.
WHAT ELSE IS E. COLI KNOWN AS?
E. coli is also known as non-Shiga producing E. coli, Escherichia coli, calibacillus, and colon bacillus.