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Medical Author:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Medical Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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Shiga Toxin-Producing E. coli Infection Facts Medical Author: Melissa Conrad Stöppler, MD Medical Editor: William C. Shiel, Jr., MD, FACP, FACR Escherichia coli, or E. coli for short, is a very common bacterium. There are hundreds of different strains of E. coli. Some are harmless while others cause serious illness. Non-pathogenic strains of E. coli -- those that do not cause disease -- are normal inhabitants of the intestinal tract in humans and animals. But certain strains of E. coli can cause severe diarrhea and infect the genital and urinary tracts. Examples of Shiga toxin-producing E. coli outbreaks The most notorious type of pathogenic E. coli is known as E. coli 0157:H7. The name refers to the chemical compounds found on the surface of the bacterium. This strain was identified in 1982 following an outbreak of diarrhea resulting from the eating of undercooked beef. The 0157:H7 E coli strain belongs to a group of bacteria known as "Shiga toxin-producing" E. coli, or STEC for short. They have also been referred to as verocytotoxic E. coli (VTEC) or enterohemorrhagic E. coli (EHEC). Outbreaks of E. coli 0157:H7-induced illness have been common in recent years. In 2011, a deadly outbreak began in Europe due to a rare strain of E coli, Shiga toxin-producing E. coli O104, or STEC O104, that produces a serious illness similar to that produced by E coli 0157:H7. At the time of the outbreak, which was centered in Germany and related to contaminated vegetables, the STEC 0104 strain had never been identified in the United States. Read more about recent outbreaks of E. coli infections » Top Searched E. coli Terms: symptoms, treatment, raw meat products, foods that contain E. coli, bacteria, fish, pathogenic, poisoning symptoms, diarrhea, bladder infection

E. coli 0157:H7 Facts

• E. coli 0157:H7 is a gram-negative bacterium that can produce a bloody diarrhea due to toxins it secretes when it infects human intestinal tracts.
  
  
• The symptoms of E. coli 0157:H7 infection may include a low fever, nausea, vomiting, stomach cramps, and bloody diarrhea.
  
  
• E. coli 0157:H7 is notorious because it can cause additional complications in children and the elderly; renal failure, anemia, and dehydration especially for children (termed HUS or Hemolytic-uremic syndrome) and spontaneous bleeding, organ failures, and mental changes in the elderly (termed TTP or thrombotic thrombocytopenic purpura). Some of these patients develop disabilities or die.
  
  
• Diagnosis is definitively made when E. coli 0157:H7 is isolated, usually from the patient's stool, and identified as serotype 0157 by immunologic tests.
  
  
• Most E. coli 0157:H7 infections resolve spontaneously and require no treatment; however supportive treatment is usually quickly required if the patient becomes dehydrated, anemic, or develops HUS or TTP.
  
  
• The majority of E. coli 0157:H7 infections have excellent outcomes. If complications develop such as severe dehydration, anemia, HUS or TTP, the outcomes can decline from good to poor quickly.
  
  
• Prevention consists of eating well cooked foods, especially hamburger, and drinking treated or pasteurized fluids. Avoiding touching or eating any food that may be contaminated with any animal or human waste will help prevent the infection.
  
  
• There is no E. coli 0157:H7 vaccine available for humans.

What is E. coli?

Escherichia coli (E. coli) are gram-negative bacteria that can survive in an environment with or without air (facultative anaerobes) and, depending on the environment, may or may not produce thin hair-like structures (flagella or pili) that allow the bacteria to move and to attach to human cells. These bacteria commonly live in the intestines of people and animals worldwide. There are many strains (over 700 serotypes) of E. coli. Most of the E. coli are normal inhabitants of the small intestine and colon and do not cause disease in the intestines (non-pathogenic). Nevertheless, these non-pathogenic E. coli can cause disease if they spread outside of the intestines, for example, into the urinary tract (where they cause bladder or kidney infections), or into the blood stream (sepsis). Other E. coli strains (enterovirulent E. coli strains or EEC) cause "poisoning" or diarrhea even though they usually remain within the intestine by producing toxins or intestinal inflammation. There are four to six groups (some researchers combine groups) of E. coli strains that comprise EEC.

• EHEC (enterohemorrhagic E. coli)
  
  
• ETEC (enterotoxigenic E. coli)
  
  
• EPEC (enteropathogenic E. coli)
  
  
• EIEC (enteroinvasive E. coli
  
  
• EAEC (enteroadherent E. coli
  
  
• EAggEC (enteroaggregative E. coli)

E. coli were first isolated by T. Escherich in 1885 and were named after him. The over 700 serotypes are identified by small antigenic changes in their surface "O" antigens (lipopolysaccharides or molecules on the bacterial surface of gram-negative bacteria), for example E. coli 0157 or E. coli 055. These serotypes are identified by immunological tests. E coli strains are further distinguished by "H" protein antigens (different types of flagella that make the bacteria motile). Consequently, a particular E. coli strain can be identified as H, followed by a number, and this identifier is added to the "O" name; for example, E. coli 0157:H7. Although this name designation seems complicated, researchers and clinicians use these antigenic identifiers to track specific E. coli strains that cause outbreaks of disease.

One particular E. coli strain, E. coli 0157:H7 is notorious for its potential to cause disease in man; the remainder of this article will focus on this E. coli strain.