E. coli virotypes Food Poisoning, Infection and Illness

Escherichia coli (E. coli) is a type of bacteria that belongs to the family Enterobacteriaceae, which includes many other common and diverse bacteria such as Salmonella, Shigella, Klebsiella and Yersinia. E. coli is normally found in the lower intestine of warm-blooded animals, including humans, where it plays a vital role in digestion and immunity. E. coli is also widely used as a model organism in biotechnology and microbiology, where it has been the host for most of the work with recombinant DNA and genetic engineering.

However, not all strains of E. coli are harmless or beneficial. Some strains have acquired virulence factors that enable them to cause various diseases in humans and animals, ranging from mild diarrhea to life-threatening infections. These pathogenic strains are classified into different groups based on their mode of transmission, their mechanism of infection and their clinical manifestations. Some of the most important groups are:

  • Enterotoxigenic E. coli (ETEC), which produces toxins that cause watery diarrhea, especially in travelers and children in developing countries.
  • Enteropathogenic E. coli (EPEC), which adheres to and damages the intestinal cells, causing diarrhea and vomiting in infants and young children.
  • Enterohemorrhagic E. coli (EHEC), which produces Shiga toxins that cause bloody diarrhea and hemolytic uremic syndrome (HUS), a serious complication that affects the kidneys and blood cells.
  • Enteroinvasive E. coli (EIEC), which invades and destroys the intestinal cells, causing dysentery-like symptoms similar to those of Shigella infection.
  • Enteroaggregative E. coli (EAEC), which forms aggregates on the intestinal cells and produces toxins that cause persistent diarrhea in children and adults.
  • Diffusely adherent E. coli (DAEC), which attaches diffusely to the intestinal cells and causes watery diarrhea, mostly in children.

E. coli infections are usually transmitted through the fecal-oral route, meaning that the bacteria are shed in the feces of infected animals or humans and contaminate food, water or other objects that are ingested by susceptible hosts. Some of the common sources of contamination are:

  • Undercooked or raw meat, especially ground beef, that contains EHEC or other pathogenic strains.
  • Unpasteurized milk or dairy products that are contaminated with EHEC or other pathogenic strains.
  • Fruits and vegetables that are irrigated or washed with contaminated water or fertilized with animal manure that contains EHEC or other pathogenic strains.
  • Drinking water that is polluted with animal or human feces that contains EHEC or other pathogenic strains.
  • Direct contact with animals or humans that carry EHEC or other pathogenic strains in their intestines.

The symptoms of E. coli infection vary depending on the strain and the host factors, but they usually include diarrhea, abdominal cramps, nausea, vomiting and fever. In some cases, complications such as dehydration, kidney failure, blood clots, seizures or death may occur. The diagnosis of E. coli infection is based on the isolation and identification of the bacteria from stool samples or other specimens using culture methods or molecular techniques. The treatment of E. coli infection depends on the severity of the illness and the type of strain involved, but it usually involves supportive care such as fluid replacement and symptomatic relief. Antibiotics are not always effective or recommended for E. coli infection, as they may increase the risk of HUS or induce resistance in some strains. Prevention of E. coli infection relies on proper hygiene practices such as washing hands before eating or preparing food, cooking meat thoroughly, avoiding raw or unpasteurized dairy products, washing fruits and vegetables before consumption, boiling or treating drinking water if its quality is doubtful, and avoiding contact with sick animals or humans.

E. coli is a versatile and adaptable bacterium that can be both a friend and a foe to humans and animals. It is important to understand its biology, diversity and pathogenicity in order to prevent and treat its infections effectively.