E. Coli and VTEC 0157

What is E. coli?

E. coli (more correctly called Escherichia coli) is a bacterium (germ). There are many strains (sub types) of E. coli. Many strains live in the gut of humans and other animals. They usually do no harm there and are part of the normal 'gut flora'. However, some strains of E. coli can cause various infections and diseases.

What infections and diseases can be caused by E. coli?

These include the following:

Urinary tract infections (UTIs)

For example, cystitis, kidney infections and other 'urine infections'. About 9 in 10 UTIs are caused by strains of E.coli. Many of the strains are those that live harmlessly in the gut, but can cause a UTI if they get into the bladder or other parts of the urinary tract. For details see separate leaflets called Cystitis, Kidney Infections, and Urine Infection in Children.

Gastroenteritis (infection of the gut)

This is commonly due to various strains that do not normally live in the gut. Gastroenteritis can cause symptoms of diarrhoea, vomiting, fever and abdominal pain. The source of the infecting strains is often from contaminated food ('food poisoning') or from other people who have the infection. Travellers diarrhoea is often caused by a strain of E. coli. See separate leaflets called Gastroenteritis in Children and Gastroenteritis in Adults.

Intra-abdominal infections

These are infections that occur inside the abdomen, often when a part of the gut is damaged or perforated. This allows the normally harmless E. coli bacteria that live in the gut to get into the abdomen and cause infection. For example, peritonitis, or an abdominal abscess that can form after a burst appendix, or following a stab wound to the abdomen.

Other infections

Other infections that are sometimes caused by strains of E. coli include: pneumonia, meningitis, infected bones and joints, and skin and soft tissue infections (especially in people who have diabetes). So, in fact, practically any area of the body can be infected with E. coli, although some areas are only rarely infected with E. coli.

Other diseases

Other diseases associated with E. coli include haemolytic uraemic syndrome and thrombotic thrombocytopaenic purpura. These are rare but serious diseases that occur as a result of a toxin (poison) that some strains of E. coli make. The most important toxin-releasing strain is called 'vero cytotoxin-producing Escherichia coli O157'. This is sometimes called VTEC 0157 or E. coli 0157.

The rest of this leaflet is just about VTEC 0157.

What is VTEC 0157?

VTEC strains of E.coli make toxins (poisons) that can cause severe diseases. The toxins are called vero cytotoxins (VTs). There are various VTEC strains that can cause disease in humans but the most important one is VTEC 0157. Although this is uncommon, it has caused several outbreaks of disease in recent years.

What are the symptoms of infection with VTEC 0157?

VTEC O157 can cause a range of symptoms ranging from none at all, to a severe life-threatening illness.

Gastroenteritis

Some people infected with VTEC 0157 have typical symptoms of a gut infection (gastroenteritis). That is, diarrhoea with or without vomiting, abdominal cramps and fever. Sometimes there is some blood mixed in with the diarrhoea. This can last a few days and then go away within a week or so, just like many other cases of gastroenteritis.

Haemorrhagic colitis

A number of people infected with VTEC 0157 develop a very inflamed colon (large bowel) which bleeds a lot. This causes very bloody diarrhoea and abdominal pains (which can be severe). Often there is no fever with haemorrhagic colitis. Symptoms can be bad for several days and then usually gradually subside and clear away. Symptoms typically clear completely within two weeks. In effect, it is like a severe bout of gastroenteritis.

Haemolytic uraemic syndrome (HUS)

Up to 1 in 10 children infected with VTEC O157 develop haemolytic uraemic syndrome, in addition to gastroenteritis or haemorrhagic colitis. Haemolytic uraemic syndrome is a condition that is triggered by the toxin made by VTEC 0157. It causes kidney failure, a type of anaemia called haemolytic anaemia, and thrombocytopaenia (lowered platelets). About 1 in 10 children who develop haemolytic uraemic syndrome die of the condition.

Thrombotic thrombocytopaenic purpura (TTP)

Some people (mainly adults) infected with VTEC O157 develop a condition called thrombotic thrombocytopaenic purpura. This can cause serious problems in the blood, kidneys and brain. Some people die of this condition.

Asymptomatic carriage

This means that some people can 'carry' the VTEC O157 in their gut for a time but without having any symptoms. However, if you carry the bacteria in your gut you will pass it out with your faeces (stools) for a time. Therefore, even if you do not have symptoms, you can pass on the bacteria to others if your hygiene is not good.

How do you get VTEC 0157?

You can become infected by eating food that is contaminated with VTEC 0157. As mentioned, VTEC 0157 is an uncommon bacteria to contaminate food, but when it does, the consequences can be serious. A number of outbreaks of disease caused by VTEC 0157 have been reported in recent years. Outbreaks have been reported where the contaminated food has been: mince, milk, yoghurt, cooked meats, meat pies, cheese, dry cured salami, raw vegetables, unpasteurised apple juice, and water.

It can take anywhere between 1 an 14 days to develop symptoms once you are infected, but most commonly it takes 3-4 days.

If you have been infected with VTEC 0157, you will pass it out with your faeces, sometimes for several weeks even after symptoms have gone. Therefore, some people pass on the bacteria to others if their hygiene is poor. For example, not washing hands after going to the toilet, and then preparing food for others.

Healthy cattle and sheep can sometimes be carriers of VTEC 0157. There have been some outbreaks linked to handling live cattle. Swimming in contaminated water has also resulted in small outbreaks.

How is VTEC 0157 infection diagnosed?

If infection with VTEC 0157 is suspected then a sample of stool (faeces) is taken. Tests in the lab can confirm the presence of VTEC 0157 bacteria and confirm the diagnosis.

What is the treatment for VTEC 0157 infection?

There is no cure for infection with VTEC 0157. However, in most cases, it causes either gastroenteritis or haemorrhagic colitis (like severe gastroenteritis). These illnesses usually clear away by themselves as the immune system clears the bacteria. The main treatment is to make sure you do not get dehydrated. So, it is important to drink plenty and some people may need a 'drip' to correct low body fluid. For details see separate leaflets called Gastroenteritis in Children and Gastroenteritis in Adults.

People who develop haemolytic uraemic syndrome or thrombotic thrombocytopaenic purpura need specialist hospital care. This aims to control the effects of the disease until the toxin and bacteria have gone from the body.

Antibiotics are not usually used for this infection. Indeed, there is some concern that giving antibiotics to children who have a gastroenteritis or colitis caused by VTEC 0157 may increase the risk of developing haemolytic uraemic syndrome. However, the management of haemolytic uraemic syndrome or thrombotic thrombocytopaenic purpura is a specialist area. Your specialist will advise on the most up to date treatment. Antibiotics may be used in certain situations.

What is the outlook (prognosis)?

As mentioned above, the problems that can occur if you are infected with VTEC 0157 can range from no symptoms at all, to a life-threatening illness. Many infected people get a nasty gut infection, but then fully recover. Typically, symptoms will clear within two weeks, except in those people who develop haemolytic uraemic syndrome or thrombotic thrombocytopaenic purpura. These complications can last much longer.

Some people have died from VTEC 0157 infection in recent years, usually as a result of haemolytic uraemic syndrome or thrombotic thrombocytopaenic purpura. For example, in 1997 it caused the death of 20 people in Scotland. If you are infected with VTEC 0157, the risk of dying from the infection is estimated to be between 1 in 100 and 5 in 100.

Can VTEC 0157 infection be prevented?

Proper storage, preparation, and cooking of food, and good hygiene helps to prevent VTEC 0157 infection (and other gut infections). In particular, always wash your hands:

• After you go to the toilet.
• Before you touch food. Also, between handling raw meat and food ready to be eaten. (There may be some bacteria on raw meat.)
• After gardening.
• After playing with pets or handling farm animals (healthy animals can carry certain harmful bacteria).

If you are infected with VTEC 0157, the following are also recommended until symptoms go and bacteria are no longer present in your stools (faeces).

• Regularly clean the toilets that you use. Wipe the flush handle and toilet seat with disinfectant (such as household bleach) after each time you use the toilet.
• Wash your hands thoroughly after going to the toilet. Don't share towels and flannels.
• Do not prepare food for others.
• Stay off work or school until advised by your doctor to return.