What is Enterohemorrhagic Escherichia coli?
Escherichia coli, or E. coli for short, is a type of bacteria shaped like a tiny rod. It usually lives harmlessly in the colon, a part of the human digestive system. However, some kinds of E. coli, known as STEC or VTEC, can cause illness because they produce harmful substances known as Shiga toxin and Shiga-like toxin (verotoxin). When these types of E. coli cause sickness in humans, we usually refer to them as EHEC.
The words “STEC,” “VTEC,” and “EHEC” are often used to describe the same harmful kinds of E. coli. One of these harmful types, known as EHEC serotype O157:H7, has been identified as a cause of severe, bloody diarrhea outbreaks and a dangerous condition known as hemolytic uremic syndrome (HUS) around the world. HUS can cause the kidneys to stop working properly and lead to potentially life-threatening complications.
What Causes Enterohemorrhagic Escherichia coli?
Infections from the bacteria E. coli O157:H7 can vary greatly. In some cases, there may be no symptoms, while in severe cases, it can lead to serious, and sometimes fatal, complications. One such complication is called hemolytic uremic syndrome, or HUS, which can cause the kidneys to stop working. Even those who survive HUS can sometimes continue to have kidney problems.
This strain of E. coli can enter the human body in several ways. These include contaminated food and water or direct contact with infected animals or humans. Most of the outbreaks are caused by eating contaminated food like ground beef, milk products, and fresh fruits or vegetables.
Cows are seen as the main source of E. coli O157:H7. This happens through using them for food, using their manure as fertilizer, and when water gets contaminated by runoff from cattle farms. While the percentage of cows that carry E. coli O157:H7 in their feces varies from 0 to 80%, it has been noted that more cows carry the bacteria during the summer months. It’s thought that warmer temperatures are more favoring to the bacteria’s ability to grow and survive.
Risk Factors and Frequency for Enterohemorrhagic Escherichia coli
The Centers for Disease Control and Prevention (CDC) reports that foodborne E. coli O157:H7 is at the root of over 63,000 illnesses every year in the United States. These illnesses result in more than 2100 people needing to go to the hospital or even dying. The economic impact of this bacteria is substantial, costing approximately $405 million every year in medical expenses, loss of life, and decreased productivity.
A 2017 report from the Foodborne Diseases Active Surveillance Network (FoodNet) in the United States ranked Shiga toxin-producing E. coli (also known as STEC) among the top nine foodborne pathogens. Compared to the rates from 2014 to 2016, the 2017 incidence of STEC infections was 28% higher. There were 57 cases of Hemolytic Uremic Syndrome (HUS, a serious condition caused by E. coli) identified in 2016, but this was not significantly different from the numbers in 2013 to 2015.
In Norway, HUS is the second most common cause of sudden kidney infections in children, with an estimated incidence rate of 0.5 cases per 100,000 children every year.
Signs and Symptoms of Enterohemorrhagic Escherichia coli
EHEC, a type of bacteria, commonly causes symptoms like bloody diarrhea (blood in stool), abdominal pain, and sometimes a high white blood cell count of more than 10,000/microL. Usually, these symptoms appear 3 to 4 days after being exposed to the bacteria. EHEC infections do not usually cause fever.
A severe complication of EHEC infection is HUS. HUS, which mainly affects young children, is characterized by anemia due to the destruction of red blood cells, impaired kidney function, and a low platelet count (thrombocytopenia). If HUS develops after bloody diarrhea caused by an EHEC infection, it is referred to as D+ HUS or typical HUS. If HUS is caused by other factors, it’s called D- HUS or atypical HUS.
Testing for Enterohemorrhagic Escherichia coli
If your doctor suspects that you might have an infection from a specific type of bacteria called EHEC, they will need to test a sample of your stool. The stool test helps determine if Shiga toxin or EHEC, substances produced by the harmful bacteria, are present in your body.
In addition, if you are showing signs of a condition called Hemolytic Uremic Syndrome (HUS) – a serious complication of EHEC infection, your doctor may also order blood and urine tests. The blood test can help determine if you have a low red blood cell count and low platelets, which are signs of HUS. The urine test can assess how well your kidneys are functioning, as HUS can affect kidney function.
Treatment Options for Enterohemorrhagic Escherichia coli
If someone has diarrhea caused by a type of bacteria called Enterohemorrhagic Escherichia coli (EHEC), they will receive support treatments. These treatments are designed to help manage the condition and improve the patient’s comfort level.
Firstly, the patient’s body may lose a lot of water and electrolytes due to diarrhea. That’s why it’s crucial to replace these vital substances, especially in those patients with a condition called Hemolytic Uremic Syndrome (HUS) that can cause organ damage.
Thanks to improvements in intensive care and dialysis, a treatment technique that removes waste materials from the blood, the survival rate of patients, especially young children, has significantly increased. Peritoneal dialysis, a type of dialysis that uses the lining of the abdomen to filter the blood, is regarded as the best option for children.
In some cases, when the kidneys are majorly affected by the disease and usual treatments aren’t effective, a bilateral nephrectomy (removal of both kidneys) can be a lifesaving procedure. It helps to prevent the spread of the disease to tiny blood vessels elsewhere in the body.
Because this disease can have serious effects, providing immediate supportive treatments may improve the patient’s chances of a better recovery. Other supportive treatments depend on the patient’s symptoms and may include:
- Red blood cell transfusions (giving the patient red blood cells from a donor)
- Platelet transfusions (giving the patient platelets, which help blood clot, from a donor)
- Plasma exchange (removing the plasma portion of the patient’s blood and replacing with donor plasma)
To prevent diseases that are spread through food, like EHEC infections, it’s important to practice good hygiene and control the contamination of food by harmful organisms and chemicals. This can be achieved through effective food safety programs. Vaccines to prevent EHEC are currently being studied, but none have been approved by the U.S. Food and Drug Administration (FDA) yet.
What else can Enterohemorrhagic Escherichia coli be?
In people showing symptoms of HUS (hemolytic uremic syndrome), two specific tests should be performed: Shiga toxin/STEC and ADAMTS13 activity. This is because the symptoms and affected organs in HUS and another condition called thrombotic thrombocytopenic purpura can be similar. If the patient is of an unusual age or doesn’t have diarrhea, a variant of E. coli could suggest a different form of HUS.
What to expect with Enterohemorrhagic Escherichia coli
Early diagnosis of EHEC infection and immediate start of fluid replenishment can greatly improve long-term health results by minimizing harm to the kidneys. Furthermore, advancements in dialysis treatments and superior care for critically ill children have noticeably reduced the immediate mortality rate of HUS. As a result, chronic issues in those who survive in the long-term are becoming more noticeable.
Possible Complications When Diagnosed with Enterohemorrhagic Escherichia coli
EHEC, a bacteria often associated with bloody diarrhea, can usually get better on its own without any lasting damage. However, it becomes severe when the patient develops Hemolytic Uremic Syndrome (HUS). Some children, after being treated for HUS, may not regain their kidney functions entirely and need long-term treatments. On the other hand, children who do recover their kidney functions may still be at risk of future kidney diseases.
Furthermore, some children might also experience unrelated lasting effects like neurological defects (problems with the nerves), insulin-dependent diabetes mellitus (a type of diabetes that requires insulin injections), pancreatic insufficiency (difficulty in digesting food), or gastrointestinal complications (problems with the digestive system).
HUS isn’t just another illness – it’s a disease with a high rate of death and problems that can affect many different body systems. Therefore, it’s important to consider the signs of the disease that aren’t related to the kidneys (extra-renal manifestations) during the acute phase. And the condition of the kidneys should be continually checked (monitored) in the long term for patients who have recovered from HUS.
- EHEC can often resolve without long-term issues
- HUS may lead to severe prognosis
- Some children can lose kidney functions permanently after being treated for HUS
- Those who regain kidney functions are still at risk of future kidney disease
- Possible unrelated problems such as neurological defects, insulin-dependent diabetes, pancreatic insufficiency or gastrointestinal complications
- HUS can lead to death and affect many body systems
- Monitoring of non-kidney related symptoms and kidney conditions in long term is important
Preventing Enterohemorrhagic Escherichia coli
There are several steps you can take to significantly reduce the risk of getting EHEC infections. These include using clean, drinkable water when preparing food, making sure that animals are slaughtered under hygienic conditions, using proper methods during food processing, cooking food thoroughly, and educating those who handle food, like farm workers, about the importance of following strict hygiene principles in the handling and preparation of food. By following these preventative measures, the occurrence of EHEC infections can be greatly reduced.
