What is **Escherichia coli (E. coli)**?

Creator: Dr_Microbe | Credit: Getty Images

**Escherichia coli (E. coli)** is a type of bacteria that lives in the intestines of humans and animals. Most strains of E. coli are harmless and are an important part of a healthy intestinal tract. However, some strains can cause illness, ranging from diarrhoea to urinary tract infections, respiratory illness, and pneumonia.

### Types of E. coli

1. **Enterotoxigenic E. coli (ETEC)**: Causes traveller’s diarrhoea and diarrhoea in developing countries.

2. **Enteropathogenic E. coli (EPEC)**: Causes severe diarrhoea in infants.

3. **Enterohemorrhagic E. coli (EHEC)**: Produces Shiga toxin, leading to severe foodborne illness. E. coli O157:H7 is a well-known EHEC strain.

4. **Enteroinvasive E. coli (EIEC)**: Invades and multiplies within intestinal epithelial cells, causing dysentery-like symptoms.

5. **Enteroaggregative E. coli (EAEC)**: Causes persistent diarrhoea in children and adults.

6. **Diffuse-adhering E. coli (DAEC)**: Associated with diarrhoea in children.

### Symptoms of E. coli Infection

Symptoms can vary depending on the strain but commonly include:

- Diarrhea (which may be bloody)

- Stomach cramps

- Nausea and vomiting

- Fever

### Sources of E. coli Infection

E. coli can be transmitted through:

- Contaminated food (especially undercooked ground beef, raw milk, and fresh produce)

- Contaminated water

- Person-to-person contact (especially in daycare centres)

- Contact with animals or their environment

### Prevention

Preventive measures include:

- Properly cooking meat, especially ground beef

- Avoiding raw milk and products made from raw milk

- Washing hands thoroughly with soap and water, especially before handling food and after using the restroom

- Washing fruits and vegetables thoroughly

- Avoiding swallowing water from swimming pools, lakes, or rivers

### Diagnosis and Treatment

Diagnosis typically involves stool samples to identify the presence of E. coli bacteria. Treatment often focuses on supportive care, such as hydration. Antibiotics are usually not recommended, particularly for EHEC infections, as they can increase the risk of complications like haemolytic uremic syndrome (HUS).

### Complications

One of the most serious complications of EHEC infection is haemolytic uremic syndrome (HUS), which can lead to kidney failure, especially in young children and the elderly.

### E. coli in Research and Biotechnology

E. coli is extensively used in biotechnology and research because it is easy to grow and manipulate genetically. It has been instrumental in the production of insulin, growth hormones, and other pharmaceuticals.

### Summary

E. coli is a diverse group of bacteria, ranging from harmless strains to those that can cause severe illness. Prevention through proper food handling, hygiene, and awareness is key to reducing the risk of infection.