Escherichia coli, also called E.coli, is a bacterium which normally lives in the intestines of mammals. All feces we eliminate daily contain trillions of bacteria like Escherichia coli.
Who ever heard of fecal coliforms in the survey to assess the quality of water and food? When looking for faecal coliforms, it is E.coli we are looking for, whose presence indicates contamination of water or food by feces.
But if Escherichia coli normally lives in the intestines of all mammals, why from time to time we hear of diseases caused by this bacterium?
There are two explanations for this question. The first is the fact that most strains of E. coli are usually harmless when confined to the intestines. The diseases arise when the bacterium reaches other organs of the body such as the bladder. Most urinary tract infections are caused by Escherichia coli, due to the proximity of the female urethra and the anus often gets past the digestive tract to the urinary tract.
Urinary tract infection is the most common infection caused by Escherichia coli, however, this bacterium can also cause several other infections such as abscesses in the liver, pneumonia, meningitis, arthritis, cholecystitis (bladder infections) etc.
A picture of grave sepsis usually occurs in patients with bowel perforation, which allows a large influx of intestinal bacteria into the abdominal cavity, causing severe peritonitis.
The second explanation lies in the fact that there are different strains of Escherichia coli, some of which are capable of causing disease even when restricted to the intestines. There are several different strains of E.coli responsible for signs of diarrhea, with varying degrees of severity. All are acquired after ingestion of water contaminated with feces. The contamination through food is also common and occurs by vegetables irrigated or washed with contaminated water or raw or undercooked food prepared by chefs or butchers who do not wash their hands properly after going to the toilet. The meat can also be contaminated at slaughter, even before reaching the butcher or supermarket.
Among the diarrhea caused by Escherichia coli, we can highlight the following strains:
EPEC - enteropathogenic E.coli: a common cause of diarrhea in children. Enteropathogenic E.coli strain is capable of adhering to the intestinal wall, causing inflammation and changing the capacity of absorbing water and food, resulting in watery diarrhea. Adults usually gain immunity against this strain, hence the reason for the diarrhea is more common in children and infants.
ETEC - enterotoxinogenic E.coli: causes diarrhea known as travelers diarrhea. The E.coli strain produces a toxin similar to the cholera bacterium, which causes a profuse watery diarrhea. This Escherichia coli is common in tropical countries, with frequent cause of diarrhea in children, natives or tourists from temperate countries. Usually the patient develops immunity after infection, which is why it usually only happens once.
EIEC - enteroinvasive E.coli: causes a picture similar to dysentery. Enteroinvasive E. coli is a strain with similar virulence to the bacteria Shigella, which causes dysentery. The clinical presentation of this infection is profuse diarrhea, often with blood, intense abdominal pain and high fever.
EHEC - enterohaemorrhagic E.coli: causes severe diarrhea and hemolytic uremic syndrome. Enterohaemorrhagic E. coli is a strain that also behaves similarly to Shigella bacterium being capable of producing a toxin that leads to highly aggressive hemorrhagic colitis. The framework of enterohaemorrhagic E.coli is also bloody diarrhea and severe abdominal pain, but with an aggravating factor: this strain of Escherichia coli can lead to the development of hemolytic uremic syndrome, a serious complication that leads to anemia and decreased platelet by mass destruction thereof, and acute renal failure which in many cases requires hemodialysis.
The enterohaemorrhagic E.coli is often responsible for serious outbreaks of food poisoning, leading to the death of some patients. In 2011 only three outbreaks of enterohaemorrhagic E.coli infection have been described, two in the U.S. (March and April) and a big story in Germany in June, with at least 520 cases and 11 deaths.
In the case of urinary tract infection occurs when bacterial contamination of faeces reaches the entrance of the urethra. This can happen during sex, especially if anal intercourse comes prior to vaginal, careless hygiene after evacuation, by vaginal douche etc. In the text on cystitis we will explain in detail how to prevent urinary tract infection.
Regarding the diarrhea caused by more virulent strains of E.coli, transmission can occur in the following ways:
Among humans: it is an unusual and transmitted by infected persons who do not wash their hands after evacuating. It is more common in nurseries and nursing homes.
By contact with animals: usually occurs after contact with farm cattle or pigs without proper hand hygiene.
With food: It is the most common form. When E.coli is in food for a few days before it is ingested, the bacteria have time to multiply. The greater the amount of bacteria ingested the greater are the chances of food poisoning. The contamination immediately before consumption by contaminated hands (usually cook) is also possible.
