The Ultimate Guide To Escherichia Coli (E. Coli)

Escherichia coli, often abbreviated as E. coli, is defined as a large group of divisive bacteria that can be found in all sorts of environments such as the intestines of animals and humans, as well as food.

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The Ultimate Guide To Escherichia Coli (E. Coli)

Although most people know that E. coli is something that can make you ill, the specific information surrounding E. coli is something that most people don’t really learn about.

Understanding the crucial information about E. coli such as its morphology, arrangement, cultural characteristics, pathogenicity, and diagnosis will allow you to learn the medical importance of E. coli and understand the various symptoms and reasoning as to why it exists.

In this guide, we’ll be taking you through all the essential information that you need to know about E. coli. Whether you are suffering from E. coli or are researching for a project, you’ll be able to gain a better understanding of how it works. 

What Is E. Coli?

Before we delve into the specifics of how E. coli works, it’s essential to learn about what it actually is. E. coli is Escherichia coli and is the name given to a large group of bacteria that is found in various environments. 

E. coli was first discovered in 1885 by Theodor Escherich when he isolated the bacteria from the feces of newborns. These bacteria are gram-negative coliform bacterium that is a facultative anaerobic and has a rod-shaped structure.

E. coli is most commonly located in the lower intestine of warm-blooded organisms such as animals and humans. 

Typically, E. coli are harmless, but there are certain serotypes such as ETEC and EPEC that can cause severe food poisoning as well as causing incidents that are related to food contamination, prompting product recalls. 

One example of a harmless strain of E. coli is found within the normal microbiota in the gut.

Rather than posing a threat, however, this strain actually has a variety of benefits such as creating vitamin K2 that allows blood to clot as well as avoiding any colonization within the intestine thanks to the pathogenic bacteria that produce a mutualistic relationship

When it comes to the environment, E. coli is primarily found in fecal matter and grows exponentially within the first three days before decreasing dramatically afterward.

This is because the cells can survive for a limited period of time outside the body. 

What Is The Scientific Classification Of E. Coli?

For those who are learning about E. coli for research purposes, it’s important to understand the various scientific classification of E. coli. In this section, we’ll be delving into the science behind E. coli, so you can learn where it fits within the bacteria domain.

Here is the scientific classification of E. coli:

  • The Domain of E. coli is Bacteria.
  • The Phylum of E. coli is Proteobacteria.
  • The Class of E. coli is Gammaproteobacteria.
  • The Order of E. coli is Enterobacterales.
  • The Family of E. coli is Enterobacteriaceae.
  • The Genus of E. coli is Escherichia.
  • The Species of E. coli is E. coli.
  • The Binomial name of E. coli is Escherichia coli.

What Is The Habitat Of E. Coli?

E. coli can be found in a variety of different environments. This is because there are all sorts of different strains of E. coli that can thrive depending on the environment.

Due to the versatility of E. coli, it’s essential that you learn about the various habitats, so you can be more aware of where it thrives. 

Here are the various environments that E. coli can be found in:


E. coli thrives within environments that have been faecally contaminated, which can include mud, sediments, or water. It is often found within human feces, which is how it was first discovered.

However, it is only able to survive for a limited time when outside the human body. 

E. coli that are formed within the human body may end up forming a mutual relationship with the host, meaning that it will not harm the human. 

Gastrointestinal Tract

The Gastrointestinal Tract, known as the GI Tract, is found in various warm-blooded organisms such as humans and animals. It is one of the primary environments for E. coli. 

GI Tract bacteria consists of between 0.1% to 1% E. coli. 

Lower Intestine

The most common place where E. coli is found is within the intestine of warm-blooded organisms such as humans and animals. This is because the intestine is home to the nutrients that E. coli needs to survive and thrive. 

Another area within the intestine where E. coli can be found is within the epithelium or mucus on the wall. This may not just be the lower intestine as it can also be located in the colon of the large intestine. 

Raw Fruits And Vegetables

Another location where E. coli can be found is raw fruits and vegetables. This is because it can latch onto the leaves when it comes into contact with them.

This is why it is important that you don’t eat raw fruits or vegetables without washing them first. 

Arrangement And Morphology Of E. Coli

The arrangement and morphology of E. coli is something that you need to know about if you are conducting research into E. coli.

Although there are lots of different strains of E. coli, the arrangement and morphology are pretty much identical across the board.

Here are some of the most essential arrangement and morphology facts of E. coli that you need to know about: 

Firstly, E. coli is known as a gram-negative (this is abbreviated to -ve) bacteria that is rod-shaped and straight. They tend to be arranged either singularly or in pairs and measure around 1–3 µm × 0.4–0.7 µm (micrometer).

E. coli is a motile bacterium as it includes peritrichous flagella in the majority of strains, but there are some strains that are non-motile. It is a non-sporing bacteria and may be fimbriated.

It may specifically have type 1 fimbriae, known as hemagglutinating & mannose sensitive which is found in both the motile and non-motile strains. 

Another important fact is that the morphology of E. coli has a polysaccharide capsule that can be demonstrated using a simple India ink preparation.

This will appear as a clear halo against a dark background. The cell’s wall is extremely thin and has either one or two layers of peptidoglycan. 

E. coli can grow within a wide range of temperatures between 15 and 45 °C, meaning that it can thrive in all sorts of environments, and is also a facultative anaerobe, meaning that it can thrive when exposed to oxygen. 

What Are The Cultural Characteristics Of E. Coli?

Understanding the cultural characteristics of E. coli is an essential part when conducting research.

Cultural characteristics are defined as the aspects and characteristics that help to identify a culture. Like all bacteria, E. coli can be defined by various aspects and characteristics. 

Here are the main cultural characteristics of E. coli that you need to know: 

Aerobic Bacteria

Firstly, E. coli is what is known as an aerobic bacterium which means that it thrives when exposed to oxygen. However, it is simultaneous a Facultative anaerobic organism meaning that it can also thrive in an environment with low oxygen levels. 

Can Grow On Ordinary Media

E. coli grows on ordinary media such as the Nutrient Agar medium, which is known as NAM. NAM is often used to cultivate E. coli in laboratories, making it an important part of E. coli research. 

Has An Optimum Temperature And pH

Lastly, it’s essential to understand that E. coli has an optimum temperature and pH level that allows it to thrive, depending on the strain of E. coli that you are dealing with.

The majority of E. coli strains thrive in temperatures of 37 °C and are capable of surviving at pH levels between 4.5 and 9.5. The optimum pH level is 7.0.

What Cultural Media Can Be Used To Grow E. Coli?

There are various cultural media that can be used to grow E. coli. We have already touched on one of them briefly, but in this section, we will be discussing which cultural media is most commonly used to grow E. coli.

Here are the cultural media that are used to grow E. coli:

Blood Agar

Blood Agar is commonly known as BA. The Blood Agar will cause the E. coli to become large, circular, and moist with gray coloring. This is because the Beta hemolytic colonies have been established. 

Cystine Lactose Electrolyte-Deficient Agar

Cystine Lactose Electrolyte-Deficient Agar is commonly known as CLED Agar. This cultural media will cause the E. coli to become yellow due to the lactose-positive conditions within the colonies. 

Eosin Methylene Blue Agar

Eosin Methylene Blue Agar is commonly known as EMB Agar. This Agar causes the E. coli to develop a metallic green sheen within the colonies. 

Liquid Media

Another common form of cultural media that is used is Liquid Media. This solution promotes tremendous growth within 12 to 18 hours after being applied.

This happens because the R form will agglutinate and form sediment located at the bottom of the test tubes. Once 72 hours of incubation have passed, you will be able to see pellicles that are floating on the surface.

Deposits will also form that can be dispersed when the test tube is shaken. 

m-ENDO Agar

m-ENDO Agar ensures that the E. coli develops a metallic green sheen. This is thanks to the lactose that has been metabolized due to the mixture of acid and aldehyde. 

MacConkey Agar 

MacConkey Agar is commonly known as MAC Agar. This cultural media will establish E. coli that is moist, smooth, and circular. It will have an entire margin that appears pink and flat. This is due to the colonies that are fermenting lactose. 

Mueller Hinton Agar

Mueller Hinton Agar is commonly known as MHA. This cultural media will cause E. coli to turn to a pale straw color. 

Nutrient Agar

Nutrient Agar is commonly known as NA. As mentioned previously, Nutrient Agar is the commonly applied cultural media when it comes to discovering E. coli.

This is because it will cause the E. coli to appear large with a circular shape as well as a low convex and grayish-white color.

There are two potential forms that can appear within the E. coli known as the Rough Form and Smooth Form, referred to as R form and S form, respectively. 

Violet Red Bile Agar

Lastly, Violet Red Bile Agar is commonly known as VRBA. This causes the E. coli to adapt a red appearance that can also boast a blue fluorescence around the edges when viewed under UV lighting. 

Infections That E. Coli Can Cause

Infections That E. Coli Can Cause

One thing that E. coli is most known for is the variety of clinical infections that it can cause.

There are various strains of E. coli that can cause infection such as the virulent form that can be found in the gut as well as extraintestinal sites that can cause infections such as urinary tract infections or wound infections among others. 

There is also the pathogenic form of E. coli that can cause all sorts of infections. Some of these infections include:

  • Abscesses in a variety of organs
  • Diarrhea
  • Dysentery
  • Neonatal meningitis
  • Pneumonia
  • Septic infections that develop from wounds
  • Septicemia
  • Urinary tract infections (commonly referred to as UTIs)

Harmful Trains Of E. Coli

Following on from the various infections that E. coli can cause, it’s essential to learn about the harmful strains of E. coli that can cause further problems. In this section, we’ll be delving into the various harmful strains of E. coli that you need to watch out for.

Here are the most common harmful strains of E. coli: 

Enterohaemorrhagic E. Coli 

Enterohaemorrhagic E. coli is commonly known as EHEC. This is one of the newest strains of E. coli that has been discovered and can cause various conditions such as colitis with symptoms including hemorrhage but an absence of fever.

This E. coli strain can produce Verotoxin (known as Cytotoxin), which can have an impact on the Vero cells within the tissue culture. 

Enteroinvasive E. Coli 

Enteroinvasive E. coli is commonly known as EIEC. This strain works differently from most harmful E. coli strains as it invades the intestinal mucosa such as dysentery bacilli rather than producing enterotoxins. EIEC can be anaerogenic as it is a late lactose fermenter.

Enteropathogenic E. Coli 

Enteropathogenic E. coli is commonly known as EPEC. EPEC can cause all sorts of problems such as infantile diarrhea.

This strain of E. coli works by adhering to the intentional mucosa and then causing a decrease in microvilli to prevent any beneficial bacteria from entering the mucosa. EPEC is also capable of producing a toxin that is like shigella. 

Enterotoxigenic E. Coli 

Lastly, Enterotoxigenic E. coli is commonly known as ETEC. This harmful strain of E. coli is well-known for causing diarrhea in small children, especially those suffering from dehydration as well ascholera infantum which is similar to cholera.

ETEC can also possess various colonization factors such as K antigen and pili which help to enhance virulence. 

How To Treat E. Coli Infections

Research has not been able to develop a cure for E. coli infections just yet, but there are ways that the infections can be treated in order to reduce the amount of pain that you may be feeling.

The treatment depends on the infection that you are dealing with. Since there are numerous strains of E. coli with differing degrees of severity, it’s essential that you understand what you are dealing with in order to get it treated properly.

Your medical professional will be able to prescribe you the appropriate medication. 

Here are some ways that you can treat an E. coli infection:

Antibacterial Medicine

Firstly, your doctor may prescribe you some antibacterial medication that can be used to treat and reduce the levels of E. coli bacteria in your body.

Some of the most common antibacterial medications prescribed are aminoglycosides, ampicillin, cephalosporins, fluoroquinolones, and sulfonamides.

Treatment For Diarrhea

If you are suffering from diarrhea, then you should make sure that you are drinking plenty of fluids to prevent yourself from getting dehydration.

It’s also essential to make sure that you are resting as much as possible. Avoiding dairy products can be a good idea as this will help ease any lactose intolerance that can occur during diarrhea. 

Treatment For E. Coli Meningitis

If you are suffering from E. coli meningitis then you will need to be prescribed some antibiotics. The most common type of antibiotic that doctors prescribe is cephalosporins, commonly known as ceftriaxone.

Treatment For E. Coli Pneumonia

Lastly, if you are suffering from E. coli pneumonia, then this needs to be taken very seriously and your doctor will most likely keep a close eye on you.

You may require respiratory support to provide you with adequate oxygenation as well as medications such as antibiotics. When it comes to E. coli pneumonia, doctors may prescribe antibiotics such as cephalosporins or fluoroquinolones.

How Can You Avoid E. Coli Infections? 

Although there are no specific cures for E. coli, there are ways that you can control or prevent E. coli infections. The main area to watch out for is food and drink as this is the main way that E. coli is passed to humans.

Making sure that you eat in establishments that have high hygiene standards is a good place to start as this implies that there is a reduced risk of contamination. 

There are also certain methods and steps you can take in order to avoid any E. coli infections. Here are the best ways to prevent infections:

  • Disinfection
  • Handwashing
  • Rigorous asepsis
  • Sterilizing equipment

What Is The Medical Importance Of E. Coli?

There are many reasons why E. coli holds medical importance and is constantly being researched. Here are just a few reasons why E. coli is medically significant:

Determine Fecal Contamination

E. coli can be used to determine how much fecal contamination is present in drinking water. This potentially saves hundreds of thousands of lives and ensures that the water you drink is not going to give you any infections or unpleasant symptoms. 

Plasmid Study

E. coli is used within the bacterial genetics field for plasmid study. Plasmids studies help researchers learn more about developing solutions that can improve our resistance to diseases among many other medical achievements. 

Produces Insulin

E. coli has been proven to produce insulin when it has gone through genetic engineering techniques. This means that it has many medical benefits for those who require insulin. 

Produces Vitamins

Lastly, E. coli has also been found to produce vitamins within the intestine. Vitamin K2 has many benefits such as helping the blood to clot and providing calcium to develop strong bones. 

Frequently Asked Questions

Is Escherichia Coli The Same As E. Coli?

E. coli is an abbreviation for Escherichia coli, meaning that they are in fact the same. E. coli is found in all sorts of environments such as foods or the intestines of animals and humans. It is one of the largest and most diverse groups of bacteria. 

What Are The First Signs Of E. Coli?

There are various symptoms that you may experience if you have E. coli and these can vary depending on the person. However, the most common symptoms include diarrhea (oftentimes bloody), severe stomach cramps, and vomiting.

Some people may experience a fever that isn’t too high. Most people tend to get better between five and seven days after their symptoms begin. 

How Do You Cure Escherichia Coli?

There are no specific treatments or cures that can heal E. coli or help to prevent further complications. However, there are certain actions you can take to ease the pain such as rest and drinking plenty of fluids to avoid dehydration and fatigue. 

What Foods To Avoid When You Have E. Coli?

There are certain foods that you should avoid when you have E. coli and that have a higher chance of giving you E. coli if you don’t have it.

It’s best to avoid consuming these foods and drinks if possible, so you can live a healthy life. Here are the foods and drinks that have a higher chance of giving you E. coli:

  • Meats that are raw or undercooked such as ground beef.
  • Raw fruits and vegetables can be contaminated, such as sprouts.
  • Untreated water
  • Unpasteurized milk and milk products that are raw such as raw milk cheese.
  • Unpasteurized apple juice or cider. 

How Is E. Coli Harmful To Humans?

E. coli is known for being potentially harmful to humans. When harmful strains of E. coli are ingested, this bacteria can travel down the digestive tract which then releases a destructive toxin known as the Shiga toxin.

The Shiga toxin can damage the lining of the small intestine which can cause an array of symptoms and have fatal consequences if left untreated. 

Who Is Most At Risk For E. Coli?

There are certain people who are more at risk from E. coli depending on their vulnerability and age. Generally speaking, if you are healthy and lead a healthy lifestyle, then you shouldn’t fair too badly from E. coli.

However, there are certain groups that need to be careful when dealing with E. coli.

These groups are adults aged 65 or over and children who are younger than five years of age. 

Other people who are susceptible to E. coli are those who have weakened immune systems, including pregnant women and those who travel to certain areas. 

How Long Does It Take For E. Coli To Go Away?

When it comes to the longevity of E. coli, how long it lasts depends on the vulnerability of the person infected as well as the severity of the bacteria itself.

Since E. coli has numerous harmful strains, the length of time it takes to go away can depend on what kind of strain you are dealing with.

Without treatment, most people recover from their E. coli infection within five to ten days, while those who sought treatment tend to recover within five days. 


In conclusion, E. coli is a large group of bacteria that can cause all sorts of uncomfortable symptoms and can be found in various environments, including foods and the intestines of animals and humans.

If you believe that you are suffering from E. coli, make sure that you stay well-rested and avoid foods that can potentially make you even sicker. Understanding where E. coli comes from will help you to avoid getting sick.

Jennifer Dawkins

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