Escherichia coli

OVERVIEW OF Escherichia coli :

Escherichia coli (E. coli) bacteria normally live in the intestines of healthy people and animals. Most types of E. coli are harmless or cause relatively brief diarrhea. But a few strains, such as E. coli O157:H7, can cause severe stomach cramps, bloody diarrhea and vomiting. It also plays a vital role in urinary tract infections.

The person might be exposed to E. coli from contaminated water or food — especially raw vegetables and undercooked ground beef. Healthy adults usually recover from infection with E. coli O157:H7 within a week. Young children and older adults have a greater risk of developing a life-threatening form of kidney failure


Only a few strains of E. coli trigger diarrhea. The E. coli O157:H7 strain belongs to a group of E. coli that produces a powerful toxin that damages the lining of the small intestine. This can cause bloody diarrhea. You develop an E. coli infection when you ingest this strain of bacteria.

Unlike many other disease-causing bacteria, E. coli can cause an infection even if you ingest only small amounts. Because of this, you can be sickened by E. coli from eating a slightly undercooked hamburger or from swallowing a mouthful of contaminated pool water.

Potential sources of exposure include contaminated food or water and person-to-person contact.

Contaminated food

The most common way to get an E. coli infection is by eating contaminated food, such as:

  • Ground beef. When cattle are slaughtered and processed, E. coli bacteria in their intestines can get on the meat. Ground beef combines meat from many different animals, increasing the risk of contamination.
  • Unpasteurized milk. E. coli bacteria on a cow's udder or on milking equipment can get into raw milk.
  • Fresh produce. Runoff from cattle farms can contaminate fields where fresh produce is grown. Certain vegetables, such as spinach and lettuce, are particularly vulnerable to this type of contamination.

Contaminated water

Human and animal stool may pollute ground and surface water, including streams, rivers, lakes and water used to irrigate crops. Although public water systems use chlorine, ultraviolet light or ozone to kill E. coli, some E. coli outbreaks have been linked to contaminated municipal water supplies.

Private water wells are a greater cause for concern because many don't have a way to disinfect water. Rural water supplies are the most likely to be contaminated. Some people also have been infected with E. coli after swimming in pools or lakes contaminated with stool.

Other causes:

Contaminated foods and water

Poor sanitization


Sea food

Raw fruits and vegetables


The stomach acid acts as a greater defense mechanism. When this bacteria comes into contact with the acid, it might result in degradation of the bacteria. The patients taking the H2 receptor blockers and other antacids might easily get the infection.

Raw or undecooked shellfish


After ingestion of E. coli O157: H7, the bacteria bind to the intestinal mucosa and begin releasing Shiga toxin. The toxin, in turn, disrupts protein synthesis in the epithelial cells lining intestinal mucosa, leading to cell death, sloughing of the mucosa, and eventual bloody diarrhea.  Following exposure to the Shiga toxin, diarrhea, often the hemorrhagic variety, develops three days after exposure to the contaminated food specimen. After three days of diarrheal symptoms, diarrhea will become bloody in approximately 90% of affected patients. 


Symptoms of infection with E. coli 0157. It typically appears 2-4 days after being exposed to the bacteria. However, symptoms may appear as early as 24 hours or as late as 1 week later.

These can include:

  • abdominal pain or severe abdominal cramping, often starting suddenly
  • watery diarrhea, beginning a few hours after the pain begins
  • bright red bloody stools around a day later, resulting from the toxin’s damage to the intestines
  • nausea and, in some cases, vomiting
  • in some cases, fever, usually below 101 degrees Fahrenheit
  • fatigue resulting from dehydration and the loss of fluids and electrolytes.


Stool and urine culture:

Isolation of the organisms and susceptibility profile and laboratory investigations are made.

Molecular and Rapid tests:

This includes immunochromatographic lateral flow devices such as dipsticks which can detect the presence of the O157 antigen in stool samples.



Stay hydrated.

Antibiotics provides greater relief.

If the infection results in diarrhoea then Loperamide and Metronidazole can be administered.

If it causes urinary tract infection then the following medicnes can be administered

  • Nitrofurantoin
  • Sulfonamides
  • Amoxicillin
  • Cephalosporins
  • Doxycycline
  • Trimethoprim/sulfamethoxazole



The prognosis is good and the infection caused by the bacterium can be subsided within 2-3 weeks.


When thawing meats:

  • Don’t defrost frozen meat unwrapped on the counter.
  • Keep frozen meat in a separate plastic bag (for example, a plastic grocery bag) when thawing.

When prepping foods:

  • Don’t rinse meat before cooking. It’s not necessary. Washing the meat could spread bacterial to nearby surfaces, utensils and other food.
  • Use a plastic or ceramic cutting board to cut raw meat. These materials can be cleaned more easily and thoroughly than wooden cutting boards.
  • Don’t “cross-contaminate” a prepping surface. If you had raw meat or chicken on a prepping surface, such as a cutting board, wash it thoroughly with soap and hot water before putting another type of food (such as a raw vegetable) on it. Better yet, use different cutting boards for the foods you are preparing.
  • Rinse all raw fruits and vegetables under cold running water before eating them. It’s ok to scrub firm produce but don’t use detergent or soap.

When cooking and serving meats:

  • Cook all meat well (undercooked meat is another source of E. coli contamination). Cooking foods well kills bacteria.
  • Use a food thermometer when cooking meat, and cook all meat and other foods to the safe temperatures recommended by the United States Department of Agriculture (see references for link).
  • Don’t put a cooked hamburger on a plate that had raw ground beef or any other raw meat on it.
  • Refrigerate leftovers right away.