E. coli is a common bug which is present everywhere in the environment.

E. coli was discovered in the human colon in 1885 by German bacteriologist Theodor Escherich. Although the bacteria were initially called Bacterium coli, the name was later changed to Escherichia coli to honor its discoverer.

Soon after its discovery, E. coli became a very popular lab organism because scientists could grow it quickly on both simple and complex media. E. coli can grow in air, using oxygen as a terminal electron acceptor (aerobically) or without air, by something called fermentative metabolism (anaerobically). The ability to grow both aerobically and anaerobically classifies E. coli as a facultative anaerobe. 

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E. coli is one of several types of bacteria (commensal organisms) that normally inhabit the intestines of humans and animals. For the most part, it helps people stay healthy by providing the body with many vitamins, such as vitamin K.

E. coli bacteria can be subdivided according to their somatic (cell-wall) or O antigens, and their flagella or H antigens. Currently there are over 160 recognized O types and 55 recognized H types, amounting to over 8000 possible OH serotypes. There are also capsular and fimbriate antigens.

 Most of the E.coli serotypes pose no threat to their hosts, but some strains are potentially fatal.

such as:

The deadly E. coli strain O157 is a new pathogen, which some scientists believe originated during a Shigella pandemic in Central America in the 1970s, when a bacterial virus transferred the gene for the Shiga toxin from Shigella to E. coli, the normally harmless inhabitant of our intestines. The ability to immunize against this disease is particularly important, because the infection does not respond well to antibiotics; indeed it is thought that they may, in fact, increase the incidence of hemolytic uremic syndrome by causing the bacteria to burst and release the Shiga-like toxin into the bloodstream.

EHEC O157:H7 has also been identified as a bioterrorism agent. There is currently no specific treatment against EHEC infection and, as already noted, antibiotics are not recommended as they prompt the liberation of toxins which can worsen the clinical course of the disease.

2. Enterotoxigenic E. coli (ETEC), which produce a toxin similar to Cholera toxin, can cause diarrhea. These strains typically cause the so-called travelers' diarrhea because they commonly contaminate food and water in developing countries.

This disease is also called Montezuma's revenge or Delhi belly.

Studies show that diarrhea caused by this type of bacteria is a major cause of infant mortality worldwide, with nearly 3 million deaths per year. Yet there is no cost-effective vaccine available to prevent this problem.

Future directions for research on enterotoxigenic Escherichia E. coli vaccines for developing countries

ETEC is the most common cause of diarrhea in the developing world, causing 280-400 million diarrheal episodes annually in children under the age of 5 years and an additional 100 million episodes in children aged 5-14 years. Furthermore, ETEC causes substantial disease in adults in developing countries, with an estimated 400 million cases per year in people over 15. ETEC is also the most common cause of travelers’ diarrhea, being responsible for one-third to one-half of all diarrheal episodes in travelers to Africa, Asia and Latin America.

3. Enteropathogenic E. coli (EPEC) are associated with persistent diarrhea (lasting 2 weeks or more) and are more common in developing countries where they can be transmitted by contaminated water or contact with infected animals.

In this work we explore the most likely cause of Dan's illness:

E. coli O157:H7 (the combination of letters and numbers in the name of the bacterial strain refers to the specific markers found on its surface and distinguishes it from other types of E. coli) is just one of the hundreds of strains of the bacterium Escherichia coli. Most strains of E. coli are harmless and live in the intestines of healthy humans and animals. Some can cause mild infections, but E. coli O157:H7 produces a powerful toxin that can cause a severe infection.

The Centers for Disease Control and Prevention (CDC) estimates that 73,000 cases of E. coli O157:H7, or simply E. coli, occur every year in the US: 2,100 people are hospitalized, and 61 people die as a direct result of E. coli infections and complications that can result from the infection. Recently, the CDC estimates of E. coli infections decreased by 36%.

About e.coli

From sushi to seviche to steak tartare, raw fish and meat are hot items in culinary circles. But before you order your next rare burger, consider this.

E. coli bacteria in contaminated food—including raw fruits and vegetables, raw seafood, undercooked beef (especially hamburger) and nonpasteurized dairy products—and in contaminated water can increase your risk of infection with E. coli bacteria. A few strains of E. coli are responsible for serious food-borne infections.

E. coli can not only survive but actively grow in many environmental waters. As E. coli are present in the feces of humans and most animals, their presence has been used as an indicator of fecal pollution for years. However, caution has to be excercised, because E. coli have been isolated from pristine waters, and birds, in particular, have been associated with causing E. coli to be present in some waters.

In California, from 1996 through 1998, more than 50% of the multi-county outbreaks with confirmed food vehicles were related to alfalfa or clover sprouts.

Escherichia coli O157:H7

Enterotoxigenic E. coli bacteria spread in contaminated food. Signs and symptoms of most of the E. coli strains are: watery diarrhea and abdominal cramping, usually lasting just a few days.The infection normally clears on its own without treatment, and most adults and children have no lasting ill effects.

The incubation period for E. coli O157:H7 infection (i.e., the period from ingestion of the bacteria to the start of symptoms) is typically 3 to 9 days, although shorter and longer periods are not that unusual. An incubation period of less than 24 hours would be unusual, however. Symptoms start after you are infected with the germ. The first sign is severe abdominal cramps that start suddenly. After a few hours, watery diarrhea starts. The diarrhea causes your body to lose fluids and electrolytes (dehydration). This makes you feel sick and tired. The watery diarrhea lasts for about a day. Then the diarrhea changes to bright red bloody stools. The infection makes sores in your intestines, so the stools become bloody. Bloody diarrhea lasts for 2 to 5 days. You might have 10 or more bowel movements a day. Some people say their stools are "all blood and no stool."

You may have a mild or no fever. You may also have nausea or vomiting. If you have any of these symptoms—watery, bloody diarrhea, cramps, fever, nausea or vomiting—try to get to your doctor right away.

The diagnosis is made by finding E. coli in a stool culture. If you have bloody diarrhea, see your doctor as soon as possible. Your doctor will do a culture to find out if you have E. coli in your intestines. The culture has to be taken in the first 48 hours after the bloody diarrhea starts.

 Don't take medicine to stop diarrhea unless your doctor tells you to. Medicine keeps your intestines from getting rid of the E. coli germ. If you are seriously dehydrated, you might need to go to the hospital to replace the fluids in your body intravenously.

You can help prevent this infection by handling and cooking meat in a safe way. For your protection, follow these rules:

·         Wash your hands carefully with soap before you start cooking.

·         Cook ground beef until you see no pink anywhere.

·         Don't taste small bites of raw ground beef while you're cooking.

·         Don't put cooked hamburgers on a plate that had raw ground beef on it.

·         Cook all hamburgers to at least 155°F. A meat thermometer can help you test your hamburgers.

·         Defrost meats in the refrigerator or microwave. Don't let meat sit on the counter to defrost.

·         Keep raw meat and poultry separate from other foods. Use hot water and soap to wash cutting boards and dishes if raw meat and poultry have touched them.

·         Don't drink raw milk.

·         Keep food refrigerated or frozen.

·         Keep hot food hot and cold food cold.

·         Refrigerate leftovers right away or throw them away.

·         People with diarrhea should wash their hands carefully and often, using hot water and soap, and washing for at least 30 seconds. People who work in daycare centers and homes for the elderly should wash their hands often, too.

·         In restaurants, always order hamburgers that are cooked well done so that no pink shows.

Hemolytic Uremic Syndrome

Hemolytic Uremic Syndrome (HUS) is a severe, life-threatening complication of infection with E. coli O157:H7. Although most people recover from the symptoms of E. coli O157:H7 infection, about 5-10% of infected individuals go on to develop HUS. Hemolytic Uremic Syndrome was first described in 1955, and is now recognized as the most common cause of kidney failure in childhood. E. coli O157:H7 is responsible for over 90% of the cases of HUS that develop in North America. In fact, some researchers now believe that E. coli O157:H7 is the only cause of HUS in children. 

HUS is an extremely complex phenomenon that researchers are still trying to fully explain. The essence of the syndrome is described by its three central features: destruction of red blood cells (hemolytic anemia), destruction of platelets (those blood cells responsible for clotting, resulting in low platelet counts, or thrombocytopenia), and acute renal failure.

Thrombotic Thrombocytopenic Purpura

Thrombotic thrombocytopenic purpura (TTP) is a clinical syndrome defined by the presence of thrombocytopenia and microangiopathic hemolytic anemia. This has generally been recognized as “adult HUS.” There are many possible causes, including E. coli O157:H7, all of which act through the common mechanism of inducing endothelial cell damage. TTP frequently leads to neurological and renal impairment in patients.

What are salmonella infections?

The following are the most common symptoms of salmonella infections. However, each individual may experience the symptoms differently. Symptoms may include: diarrhea, fever, and abdominal cramps 12 to 72 hours after infection.

Treatment for salmonella infections:

These infections generally run their course in five to seven days and often no further treatment is required. However, patients with severe diarrhea may need rehydration with intravenous fluids. If the infection spreads from the intestines, antibiotics may also be necessary.

How are salmonella infections diagnosed?

Since foods of animal origin pose the greatest threat of Salmonella contamination, do not eat raw or undercooked eggs, poultry, or meats. Remember that some sauces and desserts use raw eggs in their preparation, so be cautious of these, particularly in foreign countries. Also, follow these recommendations by the CDC:

·         Make sure poultry and meat, including hamburgers, are well-cooked, not pink in the middle.

·         Do not consume raw or nonpasteurized milk or other dairy products.

·         Thoroughly wash produce before eating it.

·         Avoid cross-contamination of foods. Uncooked meats should be kept separate from produce, cooked foods, and ready-to-eat foods.

·         All utensils, including cutting boards, knives, counters, etc., should be thoroughly washed after handling uncooked foods.

·         Thoroughly wash hands before handling foods and between the handling of different food items.

·         Thoroughly wash hands after contact with feces.

·         Thoroughly wash hands after handling any reptiles.

Typically, nontyphoidal Salmonella produces a self-limiting febrile gastrointestinal illness that is indistinguishable from that caused by other bacterial enteric pathogens. Dehydration is the principal clinical concern. The incubation period between ingestion of Salmonella bacteria and the onset of illness varies from 6 to 72 hours. 

Symptoms of salmonella infection include diarrhea, abdominal cramps, fever, nausea, and/or vomiting. The diarrhea may be non-bloody, occur several times per day, and not be very voluminous, although in severe cases it may be frequent, bloody and/or mucoid, and of high volume. Fever generally occurs in the 38°C to 39°C range. Vomiting is less common than diarrhea. Headaches, myalgia (muscle pain), and arthralgia (joint pain) are often reported as well. Whereas the diarrhea typically lasts 24 to 72 hours, patients often report fatigue and other nonspecific symptoms lasting 7 days or longer. 

Salmonella bacteria are discovered in stool cultures. Although blood cultures are rarely positive, bacteremia does occur in 5% of adults with salmonella gastroenteritis and can result in hematogenous spread to the heart (endocarditis), spleen, bones (osteomyelitis), and joints (reactive arthritis).

In the US: Over 40,000 actual cases are reported and confirmed annually in the US. As only about 3% of salmonella cases are officially reported nationwide, and many milder cases are never diagnosed, the true incidence is undoubtedly much higher. It is more common in the warmer months of the year. Approximately 31% of all food-related deaths (500 to 1,000 people) are caused by salmonella infections in the US every year.

An increase in cases has occurred in those citizens who travel abroad. Among people from the US, travel to India, Mexico, the Philippines, El Salvador, and Haiti accounts for 80% of the cases.

Internationally: Fully industrialized nations report frequencies of gastroenteritis similar to the US. Typhoid fever (and presumably gastroenteritis) is far more common in areas where sanitation is inadequate, as in underdeveloped countries. The overall risk of typhoid fever from travel to India is estimated to be 18 times higher than from any other geographic area.

Mortality/Morbidity: Salmonella infection occurs in 8.7% of nursing home residents and 7% of neonates. Bacteremia occurs in 2-14% of (the infected?)people, usually infants and the elderly. Salmonella infection is responsible for 600 deaths in the US each year.