Escherichia coli O157 H7

Escherichia coli O157:H7 is a strain of the bacterium Escherichia coli (E. coli) and one of the Shiga toxin-producing types of E. coli or STEC. It is a cause of disease, typically foodborne illness, through consumption of contaminated and undercooked food. Infections can lead to serious health problems, including diarrhea, abdominal pain, hemolytic uremic syndrome (HUS), and even death. This strain has been responsible for numerous outbreaks worldwide, highlighting the importance of food safety and public health measures.

Characteristics

E. coli O157:H7 is characterized by its ability to produce Shiga toxins, which are primarily responsible for the severe symptoms associated with infection. Unlike most strains of E. coli, which are harmless and reside in the intestines of healthy humans and animals, O157:H7 is pathogenic. The "O" in its name refers to the somatic antigen number, and the "H" refers to the flagellar antigen. This strain is also known for its inability to ferment sorbitol, which distinguishes it from most other E. coli strains during laboratory testing.

Transmission

The primary route of transmission is through the consumption of contaminated food or water. Common sources include undercooked ground beef, unpasteurized milk and juice, soft cheeses made from raw milk, and contaminated fruits and vegetables. The bacterium can also be transmitted through direct contact with animals or their environment, as well as from person to person.

Symptoms and Treatment

Symptoms of E. coli O157:H7 infection typically begin 3-4 days after exposure and may include severe stomach cramps, diarrhea (often bloody), and vomiting. Fever is less common. In some cases, particularly among children under 5 years of age and the elderly, the infection can lead to hemolytic uremic syndrome (HUS), a serious condition that can cause kidney failure and death.

Treatment primarily involves hydration and supportive care. Antibiotics are not recommended for treating E. coli O157:H7 infections, as they may increase the risk of developing HUS. Antidiarrheal medications are also discouraged as they can worsen the condition.

Prevention

Preventive measures focus on proper food handling, cooking, and hygiene practices. This includes thoroughly cooking meat, especially ground beef, to a safe internal temperature; avoiding unpasteurized dairy products and juices; washing fruits and vegetables before eating; and practicing good hand hygiene, especially after contact with animals or their environment.

Outbreaks

E. coli O157:H7 has been responsible for significant outbreaks of foodborne illness. These outbreaks often lead to recalls of contaminated food products and prompt investigations by public health authorities to identify and mitigate the source of the infection.

See Also

• Foodborne illness
• Hemolytic uremic syndrome
• Shiga toxin
• Escherichia coli