Escherichia coli Infection

Introduction

Escherichia coli (E. coli) infection is an infection caused by a bacteria called Escherichia coli (abbreviated E. coli). It can result in severe and bloody diarrhea.

• They can also lead to pneumonia, meningitis, urinary tract infections, bacteremia (bacterial infection in the blood), and sepsis.
• Some infections can cause serious health issues, especially in very young or very old people or in people whose immune systems are not strong enough.
• However, the majority of healthy individuals who contract an infection do not experience significant complications and recover on their own without treatment.

Escherichia coli (E. coli)

E. coli is a gram-negative, rod-shaped bacterium of the Enterobacteriaceae family. It is a facultative anaerobic, non-sporulating coliform bacterium that colonizes the gastrointestinal (GI) tract within a few hours of birth. E. coli is a type of bacteria that normally lives in our intestines, where it aids in the digestion and breakdown of food.

• It is usually harmless and beneficial to the organism’s health. However, some strains of these bacteria are extremely dangerous (e.g., E. coli O157:H7) and can cause severe food poisoning.
• E. coli causes disease by invading tissues, producing various toxins, adhering to tissues, and forming aggregates or clumps of bacteria.
• One of the primary causes of illness is the production of Shiga toxin by certain strains of E. coli bacteria.
• Shiga toxin can cause damage to the intestine lining, which can lead to a variety of other illnesses. As a result, the E. coli strains that produce this toxin are known as Shiga toxin-producing E. coli (STEC).
• Less common strains of E. coli can cause disease in the GI tract, most commonly manifesting as abdominal pain and diarrhea.
•  E. coli is transmitted through the fecal-oral route, which can occur with unsanitary food preparation, manure contamination of meat or produce, irrigating or washing crops or fruits with contaminated water, or drinking contaminated water.

Incidence

• According to the WHO Global Burden of Foodborne Diseases report, diarrheagenic E. coli causes more than 300 million illnesses and nearly 200,000 deaths worldwide each year. Infection rates differ by region.
• The most common pathotype causing diarrhea among travelers returning from most regions is Enterotoxigenic E. coli(ETEC).
• Most cases are seen in Asia, the Middle East, Africa, Mexico, and Central and South America.
• Fewer cases are seen in the United States, Canada, Australia, New Zealand, Japan, and Northern and Western Europe.
• Countries with intermediate risk include those in Eastern Europe, South Africa, and some Caribbean islands.
• STEC infections are more common in developed countries than in developing countries.

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Different Strains of E. Coli

Although many are harmless to humans, diarrheagenic E. coli has six categories.

Enterotoxigenic E. coli (ETEC) 

• ETEC is typically found in communities that lack adequate water and food sanitation measures.
• It is the subtype most commonly responsible for travelers’ diarrhea and dehydrating diarrhea in infants in areas with limited sanitation resources.

Enterohemorrhagic E. coli (EHEC)

• EHEC is the most common type of E. coli infection that causes disease in humans.
• Previous EHEC outbreaks have been linked to people eating contaminated fruits and vegetables, as well as undercooked beef.
• This subtype is most commonly found in ground beef.

Enteropathogenic E. coli (EPEC)

• EPEC is most commonly acquired through the consumption of unsanitary vegetable products and is identified as the source of watery diarrhea.
• It is also capable of spreading from person to person.

Enteroaggregative E. coli (EAEC)

• Researchers have recently identified EAEC as an increasingly common cause of traveler’s diarrhea in both areas with abundant sanitation resources and those without.

Enteroinvasive E. coli (EIEC)

• This type is less common than the others, and it is closely related to Shigella, a type of bacteria that causes GI distress.

Diffusely adherent E. coli (DAEC)

• This subtype of E. coli covers the surface of cells uniformly, distinguishing it from other types.
• It can cause diarrhea in humans, particularly in young children.

Causes of Escherichia coli Infection

• Escherichia coli infections are caused by ingesting specific strains of E. coli bacteria.
• As the bacteria travel down to the digestive tract, they release a toxin known as Shiga toxin, which damages the lining of the small intestine.

Risk Factors

Anyone who encounters E. coli can become ill. However, some people are more likely than others to develop problems. Risk factors include:

• Age – Young children and the elderly are more likely to develop E. coli illnesses and serious complications from the infection.
• Immune system deficiency – People with weakened immune systems, whether from AIDS or drugs used to treat cancer or prevent organ transplant rejection, are more likely to become ill after consuming E. coli.
• Consuming specific foods – Undercooked hamburgers, unpasteurized milk, apple juice or cider, and soft cheeses made from raw milk are among the riskier foods.
• The season – For unknown reasons, the majority of E. coli infections in the United States occur from June to September.
• Lower levels of stomach acid – Stomach acid provides some resistance to E. coli. You may increase your risk of E. coli infection if you take stomach acid-reducing medications such as esomeprazole, pantoprazole, lansoprazole, and omeprazole.

Mode of Transmission

One of the primary modes of transmission, like that of most other bacteria, is through contaminated food and water. It spreads more specifically through:

Contaminated ground meat

• Ground meat contains meat from multiple animals, not just one.
• As a result, virulent strains of E. coli make their way into ground meat via the intestine of an infected animal.

Unpasteurized Milk

• E. coli can occasionally enter milk via an infected cow’s udders.
• When this milk is consumed without being pasteurized, the bacteria infect humans.
• Making milk products like yogurt and cheese from this raw milk can also increase the risk of infection.
• Furthermore, milking equipment can harbor E. coli and allow it to spread.

Vegetables and fruits

• If fruits and vegetables are washed in polluted water, they can become contaminated with E. coli.
• When animals and their manure mix with the water source, the risk of infection increases significantly.
• Unpasteurized fruit juices may also contain E. coli.

Contaminated Water

• The consumption of E. coli-contaminated water, possibly while swimming in a pool, lake, or pond, may infect this disease.

Other individuals:

• You could contract E. coli from an infected person.
• The bacteria can be passed on to you if the bacteria come in contact with your hands and then do not thoroughly wash your hands before touching your mouth.

Animals:

• E. coli can also be spread through interacting with infected animals in zoos or aquariums and can also be spread through animal exhibitions.

Incubation period

• The incubation period can last anywhere between 3 and 8 days, with a median of 3 to 4 days.
• Most patients recover within 10 days, but in a small percentage of cases (particularly in young children and the elderly), the infection can lead to a potentially fatal disease called hemolytic uremic syndrome (HUS).

Signs and Symptoms of Escherichia coli Infection

The symptoms can last from a few days to more than a week.

Symptoms range from mild to moderate

• Stomach cramp
• Sudden, severe watery diarrhea that may progress to bloody stools
• Acidity
• Loss of appetite
• Fatigue
• Nausea and Vomiting
• Mild fever (about 100 to 101 F or 37.7 to 38 C)

Severe symptoms    

• Dehydration (low or no urine output)
• Renal failure (fluid retention, swelling, shortness of breath)
• Anemia (pale skin)
• Blood clotting problems (easy bruising)
• Septic shock (low blood pressure).
• Death

Diagnosis of Escherichia coli Infection

The diagnosis is usually made by

• History collection- patient’s history indicates an association with persons, foods, or fluids known to contain E. coli.
• Physical examination- to rule out the symptoms such as dehydration, anemia, etc.
• Stool cultures- A culture of E. coli from a fecal specimen on selective media (sorbitol-MacConkey agar) provides a definitive diagnosis of infection, in patients with prolonged diarrheal illness, in patients with systemic signs or symptoms, and those with dysentery.
• PCR-based assays – these strains will continue to be more frequently identified. All patients with inflammatory diarrhea should have stool cultured for E. coli.
• Complete blood count
• Renal function and electrolytes
• Identification of STECinfection
• Blood cultures
• Inflammatory markers (CRP and/or erythrocyte sedimentation rate)
• An abdominal x-ray.

Treatment of Escherichia coli Infection

• The treatment of E. coli infection focuses on supportive care and maintaining hydration status.
• Most enterohemorrhagic E. coli diarrhea patients recover without treatment within ten days, except for fluid replacement.
• There are no current treatments that can cure the infection, relieve symptoms, or prevent complications caused by E. coli. For most people treatments include
  • Adequate Rest
  • Fluids to prevent dehydration and fatigue
  • Keeping an eye out for more severe symptoms that necessitate medical attention
• Avoid taking anti-diarrheal medications because they slow the digestive system and prevent the body from eliminating toxins.
• Antibiotics are generally not recommended because they increase the risk of serious complications and do not appear to help treat the infection.
• Patients with severe HUS manifestations may benefit from hemodialysis to treat volume, electrolyte, and uremia issues associated with acute renal failure and anemia is treated with blood transfusion.
• The monoclonal antibody eculizumab may hasten recovery from E. coli infection.

Complications

Approximately 10% of people infected with E. coli develop complications. These complications could result in disability or death. The following are the major complications:

• Thrombotic thrombocytopenic purpura (TTP)
• Hemolytic-uremic syndrome (HUS)
• Hemorrhagic (bloody) diarrhea
• Infections in the abdomen and pelvis
• Pneumonia
• Bacteremia (bacteria entering into the bloodstream)
• Meningitis (occurs when bacteria cross the blood-brain barrier)
• Urinary tract infections

Prevention of Escherichia coli Infection

• Thoroughly wash your hands with soap and running water
  • After using the restroom or changing diapers,
  • Before preparing or eating food,
  • After coming into contact with animals or their environments (at farms, petting zoos, fairs, or even your own pets in your own yard).
• Wash hands, counters, cutting boards, and utensils thoroughly after coming into contact with raw meat to avoid cross-contamination in food preparation areas.
• Thoroughly cook the meats.
  • Ground beef and needle-tenderized meat should be cooked to a temperature (70 °C) of at le°F160 F/70 C.
  • It is best to use a thermometer because meat color isn’t a good indicator of “doneness.”
• Do not consume
  • Raw milk,
  • Unpasteurized dairy products,
  • Unpasteurized juices (like fresh apple cider),
  • Raw dough or batter.
• When preparing food, follow the four steps to food safety:
  • Clean,
  • Separate,
  • Cook, and
  • Chill.
• When traveling abroad, take precautions with food and water.
• If you’ve been infected, don’t cook or prepare food for 48 hours after your symptoms have subsided.
• When swimming or playing in lakes, ponds, streams, swimming pools, and backyard pools, avoid swallowing water.
• Wash soiled clothing and bed linen separately from other clothes in a washing machine at the highest temperature possible (for example, 60°C)
• Clean the outside of the washing machine with hot water and detergent after any heavily soiled load
• Disinfectant sprays and wipes or alcohol-based wipes may be used on toilet seats and other surfaces, but only after any visible soiling has been removed.
• Thick household bleach is highly effective.
  • For soiled surfaces, dilute one part of bleach to every 10 parts of water and
  • For other hard surfaces, dilute one part of bleach to every 100 parts of water.
• Use heavy-duty domestic rubber gloves and disposable cloths for cleaning.
• Dispose of clothes by placing them in a plastic bag, sealing the neck, and placing them in household waste.
• Deal with any feces spillage immediately using heavy-duty domestic rubber gloves, clean the soiled area with hot water and detergent, then clean gloves and thoroughly wash hands. 

Prognosis

• People infected with E. coli O157:H7 usually have a self-limiting disease with a good prognosis.
• However, as complications arise, the prognosis deteriorates. Hydration reduces the likelihood of complications and improves the outcome.
• People who develop hemorrhagic diarrhea and are treated promptly have better outcomes and spend less time in the hospital. E. coli complications, such as HUS and TTP, have a range of prognoses ranging from good to poor, depending on the individual’s overall health and how quickly the complications are diagnosed and treated.
• Some people can recover completely, while others may need IV fluids, plasma exchange, plasma infusion, or dialysis, as well as treatment for end-organ failure (usually kidney failure) and neurologic problems.
• A small percentage of TTP patients (around 10%) will die. Although rare, relatively healthy children and adults have died as a result of dehydration caused by Escherichia coli infections.

Hemolytic Uremic Syndrome (HUS)

• Some people, particularly children aged five and under, who become infected with STEC develop hemolytic uremic syndrome (HUS).
• It is one of the more serious consequences of an Escherichia coli infection.
• Toxins from STEC in the intestines cause diarrhea, travel into the bloodstream, destroy red blood cells (hemolysis), and harm the kidneys.
• Following a GI illness, kidney function deteriorates.
• This potentially fatal illness affects about 5–10% of people infected with STEC.
• Those with HUS are usually hospitalized because the kidneys may stop functioning completely, which can be life-threatening.
• People who develop HUS typically recover within a few weeks, but if it is not treated appropriately, it can be fatal.

Early symptoms of HUS include:

• Diarrhea (usually bloody).
• Fever.
• Stomach discomfort
• Vomiting.

As the disease progresses, symptoms include:

• Oliguria (reduced urination) and hematuria (blood in the urine)
• Tired.
• Anemia
• Prone to bruising
• Rapid heartbeat
• Lightheadedness.
• Sleepiness, confusion, and seizures.
• Kidney failure

If diarrhea is severe (lasting more than three days or you are unable to stay hydrated), seek emergency medical attention.

HUS, if it develops, appears 7 days after the first symptoms, IV fluids, blood transfusions, and dialysis are used to treat it (for a short period).

Summary

• E. coli is a gram-negative bacterium that can be found all over the world. Many subtypes of this bacterial species cause a wide range of human diseases. The bacteria can be passed from person to person as well as through contaminated food and water.
• Nausea, vomiting, diarrhea, and stomach cramps are the initial symptoms. Fever and bloody diarrhea may also occur, depending on the type of bacterial infection.
• Immunological tests or culturing bacteria from the patient’s stool, food, or fluid source are used to make a definitive diagnosis.
• Many patients do not require treatment because the disease is self-limiting; however, patients with serious infections may need to be hospitalized.
• Most E. coli strains are virulent, but they do occasionally escape the GI tract. Most diarrheal infections, meningitis, septicemia, and urinary tract infections are caused by virulent strains of E. coli which can lead to death.

References

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