What is E. coli? 10 Things You Need to Know
Escherichia coli is a rod-shaped bacterium that can be the cause of many forms of illness from food poisoning to urinary tract infections.
Large outbreaks of E. coli can often make news headlines with potentially serious implications for public health as well as food providers and manufacturers who could suffer from loss in revenue, recalls or even legal action.
Read on for 10 things about E. coli from Addmaster:
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Escherichia coli, pronounced Esh-er-EE-key-ah Kohl-eye, incorporates over 45 different strains, and while some are harmless, others can cause an array of harmful infections.
Escherichia coli, more commonly known as E. coli, is a diverse group of bacteria that includes both harmless and pathogenic strains. These bacteria are rod-shaped and gram-negative, meaning they have a specific cell wall structure that makes them distinct from gram-positive bacteria. The harmless strains of E. coli are usually part of the normal flora of the human gut, where they play a beneficial role in digesting food and producing vitamin K.
Pathogenic strains of E. coli, however, can cause a variety of illnesses. These strains are often categorized based on their mechanisms of pathogenicity and the diseases they cause. For instance, Enterotoxigenic E. coli (ETEC) produces toxins that cause watery diarrhoea, often referred to as "traveller’s diarrhoea." Enteropathogenic E. coli (EPEC) can cause severe diarrhoea in infants, especially in developing countries. Enterohemorrhagic E. coli (EHEC), including the infamous O157 strain, can cause bloody diarrhoea and hemolytic uremic syndrome (HUS), a serious condition that can lead to kidney failure.
The ability of E. coli to cause disease is due to various virulence factors. These include toxins, adhesion molecules that allow the bacteria to attach to and invade cells, and mechanisms to evade the host's immune system. Understanding the diversity of E. coli strains and their pathogenic mechanisms is crucial for developing targeted treatments and preventive measures.
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Originally discovered and named Bacterium coli commune in 1885 by German-Austrian paediatrician Theodor Escherich, it was reclassified in 1895 and renamed after its discoverer.
The discovery of E. coli dates back to 1885 when Theodor Escherich, a German-Austrian paediatrician, identified the bacterium in the faeces of healthy individuals. Escherich named it Bacterium coli commune, highlighting its common presence in the colon. His work was groundbreaking, as it provided insights into the role of bacteria in the human gut and their impact on health.
In 1895, the bacterium was reclassified and renamed Escherichia coli in honour of Escherich’s contributions to microbiology and paediatric medicine. This reclassification recognised the distinct characteristics of E. coli and its importance in both health and disease.
Escherich’s discovery laid the foundation for understanding the complex relationships between humans and their microbiota. His work emphasised the dual nature of bacteria, capable of both beneficial and harmful interactions with their hosts. Over the years, research on E. coli has expanded, leading to the identification of various strains and their specific roles in health and disease. Today, E. coli remains a model organism in microbiology, genetics, and biotechnology, illustrating the enduring legacy of Theodor Escherich’s discovery.
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Most strains are usually found in the digestive tract of humans and animals as part of the microbiome and are unable to survive on surfaces or in the air, so E. coli cannot be transmitted by coughing or sneezing.
E. coli is predominantly found in the intestines of humans and warm-blooded animals, where it forms a key component of the gut microbiome. This microbiome plays a vital role in digestion, immune function, and overall health. E. coli helps break down food, produce essential vitamins, and inhibit the growth of pathogenic bacteria by competing for nutrients and space.
Because E. coli thrives in the moist, nutrient-rich environment of the gut, it does not survive well on dry surfaces or in the air. This limitation means that E. coli is not typically transmitted through respiratory droplets, unlike airborne pathogens such as influenza or the common cold. Instead, E. coli is primarily spread through the faecal-oral route. This transmission can occur when individuals consume contaminated food or water, or when they come into contact with faecal matter and then touch their mouths.
To prevent the spread of E. coli, it is essential to practice good hygiene, especially handwashing with soap and water after using the toilet, before preparing or eating food, and after handling animals. Proper sanitation and cooking practices are also critical in reducing the risk of E. coli infection.
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When certain E. coli strains enter the urinary system, they can cause urinary tract infections such as cystitis, and while most patients recover after a few days, some serious cases require a course of antibiotics.
Urinary tract infections (UTIs) are among the most common bacterial infections, particularly in women. E. coli is responsible for the majority of these infections. The bacteria can enter the urinary system through the urethra and travel to the bladder, where they can cause inflammation and infection, a condition known as cystitis.
Symptoms of a UTI caused by E. coli include a strong, persistent urge to urinate, a burning sensation during urination, cloudy or strong-smelling urine, and pelvic pain. In some cases, the infection can ascend to the kidneys, leading to a more serious condition called pyelonephritis, which can cause fever, chills, and back or side pain.
Most UTIs are treated effectively with a course of antibiotics, which eliminate the bacteria causing the infection. However, the rise of antibiotic-resistant strains of E. coli has made some UTIs more difficult to treat. This resistance underscores the importance of using antibiotics judiciously and exploring alternative treatments, such as probiotics and natural remedies, to prevent and manage UTIs.
Preventive measures for UTIs include staying hydrated, urinating regularly, wiping from front to back after using the toilet, and avoiding irritating feminine products. For individuals prone to recurrent UTIs, additional strategies, such as taking prophylactic antibiotics or using urinary antiseptics, may be recommended.
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Other strains can cause gastrointestinal infections, resulting in stomach cramps, vomiting, or diarrhoea. Again, while most symptoms pass after a short illness, treatment by antibiotics may be required for more severe cases.
Gastrointestinal infections caused by E. coli are typically associated with consuming contaminated food or water. Symptoms of these infections can range from mild to severe and include stomach cramps, vomiting, and diarrhoea. The severity of the symptoms often depends on the specific strain of E. coli involved and the health of the infected individual.
Enterotoxigenic E. coli (ETEC) is a common cause of traveller’s diarrhoea, characterised by watery diarrhoea, abdominal cramps, and nausea. This condition is usually self-limiting, with symptoms resolving within a few days. However, maintaining hydration is crucial, especially for young children, the elderly, and those with weakened immune systems.
Enteropathogenic E. coli (EPEC) and Enteroaggregative E. coli (EAEC) are other strains that cause prolonged diarrhoea, primarily affecting infants and children in developing countries. These infections can lead to dehydration and malnutrition if not properly managed.
In more severe cases, such as those caused by Enterohemorrhagic E. coli (EHEC), the infection can lead to bloody diarrhoea and serious complications like hemolytic uremic syndrome (HUS). HUS is a life-threatening condition that can cause kidney failure, hemolytic anemia, and thrombocytopenia (low platelet count).
Treatment for E. coli gastrointestinal infections typically involves supportive care, including rehydration and electrolyte replacement. Antibiotics are generally not recommended for EHEC infections, as they may increase the risk of HUS. However, for other strains, antibiotics may be prescribed if the infection is severe or prolonged.
Preventive measures include practicing good food hygiene, such as cooking meat thoroughly, avoiding unpasteurised dairy products, and washing fruits and vegetables before consumption. Traveler's to areas with poor sanitation should also be cautious about consuming street food and untreated water.
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The E. coli O157 strain is most commonly associated with food outbreaks and often makes headlines. This strain can cause an infection with fewer than 10 bacteria and produces Shiga toxins, which can lead to severe diarrhoea and kidney failure.
E. coli O157 is one of the most notorious strains due to its association with severe food borne outbreaks. This strain produces Shiga toxins, which are potent virulence factors capable of causing significant damage to the intestinal lining and other organs. The low infectious dose of fewer than 10 bacteria makes it particularly dangerous, as even minimal exposure can lead to infection.
The symptoms of an E. coli O157 infection typically begin with severe abdominal cramps and watery diarrhoea, which can progress to bloody diarrhoea. In some cases, the infection can lead to hemolytic uremic syndrome (HUS), a serious condition that primarily affects young children, the elderly, and those with compromised immune systems. HUS can result in kidney failure, hemolytic anemia, and low platelet count, requiring intensive medical treatment and sometimes dialysis.
Outbreaks of E. coli O157 are often linked to contaminated food products, including undercooked ground beef, unpasteurised milk and juice, raw fruits and vegetables, and contaminated water. Person-to-person transmission can also occur, especially in settings where hygiene practices are inadequate, such as daycares and nursing homes.
Public health agencies play a critical role in managing and preventing outbreaks of E. coli O157. This includes tracing the source of contamination, issuing recalls for affected products, and providing guidelines for safe food handling practices. Education and awareness campaigns also emphasise the importance of cooking meat to the appropriate internal temperature, avoiding cross-contamination in the kitchen, and practicing good hand hygiene.
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Undercooked meat, unpasteurised dairy products (such as milk and cheese), and vegetables where sewage has been used in fields causing contamination can all pose a risk of E. coli O157.
The risk of E. coli O157 contamination in food is a significant public health concern. Undercooked meat, particularly ground beef, is a common source of infection. The grinding process can distribute E. coli bacteria throughout the meat, making it essential to cook ground beef to an internal temperature of at least 160°F (71°C) to ensure safety.
Unpasteurised dairy products, including milk, cheese, and juice, are also potential sources of E. coli infection. Pasteurisation involves heating the product to a temperature that kills harmful bacteria without significantly affecting taste or nutritional value. Consuming unpasteurised products increases the risk of ingesting E. coli and other pathogens.
Contamination of fruits and vegetables can occur when they are grown in fields irrigated with water containing sewage or manure. This contamination can persist through the food supply chain if proper washing and handling practices are not followed. Leafy greens, such as lettuce and spinach, are particularly susceptible to contamination due to their large surface area and close contact with soil.
To reduce the risk of E. coli infection, it is crucial to follow safe food handling practices. This includes thoroughly cooking meat, avoiding unpasteurised dairy products, washing fruits and vegetables under running water, and using separate cutting boards for raw meat and produce to prevent cross-contamination. Additionally, consumers should be aware of food recalls and adhere to any warnings issued by public health authorities.
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Sewage or E. coli-infected faeces can be present in lakes and natural pools, so avoid entering the water if any hygiene warnings are present.
Natural bodies of water, such as lakes, rivers, and pools, can become contaminated with E. coli through the introduction of sewage or faeces from infected animals or humans. This contamination poses a risk to swimmers and others who come into contact with the water. E. coli can enter the water through various routes, including agricultural runoff, stormwater, and malfunctioning sewage systems.
Swimming in contaminated water can lead to gastrointestinal infections, skin rashes, and other health issues. Symptoms of waterborne E. coli infection are similar to those caused by food borne exposure and can include diarrhoea, abdominal cramps, and vomiting.
To protect public health, local authorities often monitor water quality and issue warnings or closures when E. coli levels exceed safe limits. It is important to heed these warnings and avoid swimming in contaminated water. Swimmers should also practice good hygiene, such as showering before and after swimming, avoiding swallowing water, and ensuring that children do not swim in diapers.
Efforts to reduce water contamination include improving sewage treatment infrastructure, implementing best practices for agricultural runoff management, and educating the public about the importance of maintaining clean water sources. Community involvement and adherence to guidelines can significantly reduce the risk of waterborne E. coli infections.
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Infections are best prevented by practicing good personal hygiene, including washing your hands thoroughly after going to the toilet, when preparing food, or after touching animals.
Good personal hygiene is one of the most effective ways to prevent E. coli infections. Handwashing with soap and water is a simple yet powerful practice that can reduce the transmission of E. coli and other pathogens. Key times for handwashing include after using the toilet, before preparing or eating food, after handling raw meat, and after touching animals or their environments.
To wash hands effectively, it is recommended to use warm water and soap, scrubbing all parts of the hands, including the backs, between the fingers, and under the nails, for at least 20 seconds. Rinsing thoroughly and drying with a clean towel or air dryer is also important.
In addition to handwashing, other personal hygiene practices can help prevent infection. These include keeping kitchen surfaces and utensils clean, avoiding cross-contamination by using separate cutting boards for raw meat and other foods, and refrigerating perishable foods promptly to prevent bacterial growth.
Educating children about good hygiene practices from a young age can instil lifelong habits that reduce the risk of infections. Schools, childcare centres, and community organisations can play a crucial role in promoting hygiene education and providing facilities that support proper handwashing and sanitation.
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Cooking food thoroughly, using a digital thermometer such as Thermapen, and washing salad, fruit, and vegetables with water or a vegetable wash, such as Fit, to remove contaminants can also reduce the risk of contracting a food borne E. coli infection.
Proper food preparation and cooking techniques are essential for reducing the risk of food borne E. coli infections. Cooking meat to the appropriate internal temperature is crucial to killing E. coli bacteria. A digital food thermometer, such as a Thermapen, provides an accurate way to ensure meat is cooked safely. Ground beef should be cooked to an internal temperature of at least 160°F (71°C), while steaks and roasts should reach at least 145°F (63°C) and then rest for three minutes.
Washing fruits and vegetables under running water can help remove surface contaminants. For produce with thick skins or rinds, using a brush to scrub the surface can be effective. Commercial vegetable washes, like Fit, can also be used to help eliminate bacteria and pesticides from the surface of fruits and vegetables. However, it is important to follow the manufacturer's instructions and rinse the produce thoroughly after using these products.
In addition to washing and cooking food properly, other preventive measures include avoiding raw or undercooked foods, especially when traveling to areas with poor sanitation. Choosing pasteurised dairy products and ensuring that food is stored at safe temperatures can also reduce the risk of E. coli infection.
By following these guidelines and being vigilant about food safety, individuals can significantly reduce their risk of contracting food borne illnesses caused by E. coli. Public health agencies and food industry professionals also play a critical role in ensuring that food safety standards are met and that consumers are informed about potential risks and preventive measures.
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References
1) E. coli: Infection, Causes, Symptoms & Treatment / Cleveland Clinic / https://my.clevelandclinic.org/health/diseases/16638-e-coli-infection
2) E. coli / World Health Organization / https://www.who.int/news-room/fact-sheets/detail/e-coli
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