Enterohaemorrhagic Escherichia coli (EHEC) Infection: Symptoms, Causes, Treatment, and Prevention

1A03.3 Enterohaemorrhagic Escherichia coli (EHEC) Infection

Enterohaemorrhagic Escherichia coli (EHEC) is a group of Escherichia coli (E. coli) strains that produce potent toxins called Shiga toxins (Stx), which can cause severe gastrointestinal illness. EHEC is best known for causing bloody diarrhea, abdominal pain, and can lead to more serious complications such as hemolytic uremic syndrome (HUS), a life-threatening condition that can result in kidney failure. The most commonly recognized strain of EHEC is E. coli O157:H7, though other non-O157 strains can also cause similar illness.

Pathogenesis

EHEC infections typically occur when a person ingests contaminated food or water, especially undercooked ground beef, unpasteurized dairy products, or contaminated vegetables. The bacteria enter the gastrointestinal tract, where they adhere to the epithelial cells lining the colon.

Once attached, EHEC produces Shiga toxins that damage the cells of the intestines and induce inflammation. The toxins can also enter the bloodstream and affect other organs, particularly the kidneys. The severity of the infection can vary, from mild diarrhea to more severe, bloody diarrhea and systemic complications.

Symptoms

The symptoms of EHEC infection can range from mild to severe and may include:

• Bloody diarrhea (the hallmark symptom)
• Severe abdominal cramps
• Fever (may be present, but is often low-grade)
• Nausea and vomiting (in some cases)
• Fatigue and general malaise

In severe cases, particularly with certain strains of EHEC, complications such as hemolytic uremic syndrome (HUS) can develop, characterized by:

• Acute kidney failure
• Low platelet count (thrombocytopenia)
• Hemolytic anemia (destruction of red blood cells)

HUS is more common in young children, the elderly, and individuals with weakened immune systems, and it can lead to long-term health problems, including permanent kidney damage.

Diagnosis

Diagnosing an EHEC infection typically involves:

• Stool culture: A stool sample is cultured to identify the presence of E. coli and to determine whether the strain produces Shiga toxins. Special selective media are used to isolate EHEC strains, especially E. coli O157:H7.
• PCR testing: Polymerase chain reaction (PCR) is a rapid method to detect Shiga toxin genes and confirm the presence of EHEC strains.
• Laboratory tests for HUS: If the infection has led to complications like HUS, tests to assess kidney function, platelet count, and hemoglobin levels may be conducted.

Treatment

Treatment for EHEC infections focuses on supportive care, as there is no specific antibiotic treatment for the infection. In fact, using antibiotics in some cases can increase the risk of complications like HUS. The management of EHEC infections typically involves:

• Hydration: Oral or intravenous fluids to prevent dehydration caused by diarrhea and vomiting.
• Pain relief: Medications like acetaminophen for abdominal cramps or fever (although nonsteroidal anti-inflammatory drugs [NSAIDs] should be avoided, especially in the case of HUS).
• Monitoring: Close monitoring for signs of complications, especially in vulnerable populations. If HUS develops, hospitalization and more intensive treatments like dialysis may be required.

In rare cases where EHEC infection leads to severe kidney dysfunction or HUS, additional medical interventions such as blood transfusions or dialysis may be necessary.

Prevention

Preventing EHEC infections involves practicing proper food safety and hygiene, including:

• Cooking meat thoroughly: Especially ground beef, which should be cooked to an internal temperature of 160°F (71°C) to kill the bacteria.
• Avoiding unpasteurized products: This includes unpasteurized milk, juices, or cider, which can harbor EHEC bacteria.
• Hand hygiene: Washing hands thoroughly with soap and water, especially after handling raw meat, using the bathroom, or caring for someone with symptoms of gastrointestinal illness.
• Safe water: Drinking only treated or filtered water, especially when traveling to regions with poor sanitation.

Prognosis

Most people with EHEC infections recover with supportive care, but complications such as HUS can lead to more serious outcomes, including kidney failure or long-term health effects. In children, the elderly, or those with compromised immune systems, the infection can be particularly dangerous. Timely medical attention and appropriate treatment significantly improve the chances of recovery.

The above information is provided as general reference material; please be sure to consult a specialist for accurate diagnosis and treatment tailored to your individual situation.