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Infection caused by Escherichia coli

Escherichia Coli Vall d'Hebron



The Escherichia coli (E. coli) bacteria is one of the most common causes of human illness. It forms part of the digestive flora and is always present in faecal matter.

By little known mechanisms it episodically causes disease in humans, either due to mutations that make it resistant to our body’s control mechanisms, or because it is present in places it should not normally be, such as the urinary tract or in the blood itself.






E. coli infections cover a range of severities, from a urinary tract infection which causes urinary discomfort, to infections from very aggressive strains such as the O157 strain: H7 causes Haemolytic Uraemic Syndrome (HUS).

A urinary infection caused by E. coli is the most common infection caused by the bacteria.

  • When only the lower urinary tract is affected, it causes pain and discomfort when urinating.
  • When the upper urinary tract (kidneys) is affected it causes high fever, back pain and pain when urinating.

The low-severityE. coli infection that leads to a urinary tract infection is much more common than that which leads to HUS, which is considered a rare condition, and very uncommon in the general population.

In the case of HUS, a rare condition as previously stated, the E. coli bacteria causes bloody diarrhoea and blood clotting in the smallest veins (thrombotic microangiopathy). This leads to kidney failure and also the alteration of other organs such as the heart and brain.

HUS is a serious phenomenon, which if not diagnosed and treated early, can cause death.



Infection with E. coli, which primarily affects the urinary tracts, causes discomfort when urinating, pain and increased frequency of urination, and fever if the kidneys are affected.

HUS is characterised by a feeling of general unwellness, bloody diarrhoea, with or without a fever.


Who is affected by the condition?

Infection by E. coli, normally a urinary infection, affects breastfeeding infants who do not have control of their sphincters, something which facilitates the extension of the intestinal flora into the urinary tract, and also in women of childbearing age.

HUS can occur at any age, but is most common between the ages of 4 and 12, after having consumed foods contaminated with E. coli O157, normally meat or dairy products from cows that are themselves infected with E. coli O157.



E. coli is diagnosed in the Microbiology laboratory, using cultures of a suitable medium, or through detection using techniques of molecular biology.


Standard treatment

The treatment is an antibiotic, either oral or intravenous, depending on the extent of the infection and the patient’s general condition.

The treatment for HUS caused by E. coli is always hospitalisation, with the possibility of haemodialysis being prescribed to treat renal failure.

Patients with HUS produced by E. coli very often make a full recovery, despite it being a serious disease.


Standard tests

In the case of suspected E. coli, it is necessary to identify E. coli, generally in the blood or urine, through cultures, to confirm the diagnosis and prescribe the appropriate antibiotic.

Additionally, if infection by E. coli is confirmed, an image test such as an ultrasound is indicated in order to evaluate the state of the kidneys and urinary tracts.

If HUS is suspected, hospitalisation is always indicated to check for signs of thrombotic microangiopathy (TMA): anaemia, renal failure, decreased platelet count, and broken or fragmented red blood cells.



A universally effective prevention for E. coli does not exist.

It is important to drink a lot of water in order to urinate every 2-3 hours, and above all not to hold pee in when you feel the urge to go.

Veterinary control of animals who carry E. coli O157 is fundamental for the prevention of HUS.

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Dr. Tomàs
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Head of Department
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Infectious Diseases
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Nursing Supervisor
Infectious Diseases
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