What is E. coli?

E. coli is a species of bacteria that are gram-stain negative and rod shaped. E. coli commonly live in the intestines of healthy individuals. The complete scientific name of the bacteria is termed Escherichia coli. Most E. coli are harmless to humans, but a few strains of the bacteria can cause symptoms of severe abdominal cramps, bloody diarrhea, nausea and vomiting, dehydration and if not treated, can lead to shock and death. E. coli can cause urinary tract infections, meningitis, pneumonia, abdominal infections as well as sinusitis, osteomyelitis, and sepsis.

Early Symptoms of E. Coli Infection

Early symptoms of E. coli O157:H7 infection usually appear about three to five days after a person ingests the bacteria. Symptoms of E. coli infection are

  • nausea,
  • vomiting,
  • stomach cramps, and
  • diarrhea that often is bloody.

Is E. coli contagious?

Some E. coli bacteria are contagious while others are not, depending on the E. coli strain and/or the infection type. Some strains that cause gastrointestinal problems (enteropathogenic E. coli) can be transmitted person to person, usually by the oral/fecal route, and even indirectly by contaminated food or water. The E. coli organisms can survive on contaminated utensils and other household items for short time periods. Foods that are sources for diarrhea-causing E. coli include:

  • contaminated meat (raw or undercooked),
  • unpasteurized milk, and
  • raw fruits and vegetables.

In addition, water can be contaminated with E. coli. This can be the source of infection through swimming, drinking, consuming ice and eating any food washed with or exposed to contaminated water.

Other E. coli strains that may cause urinary tract infections (UTIs), for example, are not considered to be contagious. Casual contact (shaking hands, kissing) will not usually transmit E. coli person to person. However, some strains of E. coli, including the diarrhea-causing enteropathogenic strains, can be contagious.


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When will I know I’m infected with E. coli?

Symptoms depend on the age of the patient, the strain of E. coli, and the organ system involved and may include

Some other infections outside the intestinal tract can be caused by E. coli infection. Examples are

E. coli infection can lead to shock and death if untreated.

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How long does it take for symptoms and signs of an E. coli infection to occur?

The time period from exposure to the E. coli to when disease symptoms and signs develop (incubation period) ranges from about 1 to 10 days and usually occurs in three to four days. The symptoms an individual may develop vary greatly.

How does E. coli spread?

E. coli is easily spread to other persons by fecal contamination of water and/or food, especially in raw meat, raw milk, and raw vegetables. Many outbreaks of diarrheal illness are spread this way. Moreover, person-to-person contact easily spreads the organisms. Also, indirect spread of E. coli can also occur since the organisms can survive outside the body on utensils and many other surfaces. The organisms can cause wound infections or even spread to the brain (meningitis). If the intestinal tract is injured by trauma, ulceration, or other diseases, it may allow E. coli to cause infection of the abdomen (peritonitis) and/or sepsis.


Bowel regularity means a bowel movement every day. See Answer

When will I know if I’m cured of E. coli?

Individuals can be cured of E. coli infections. The period of time it takes for antibiotics and/or supportive care (hydration, oxygenation, blood pressure support, for example) to cure E. coli infections varies with the severity of the infection. Some infections can be treated with only antibiotics and cures make take from about 5 to 21 days. Other infections may require surgical drainage and/or debridement. These infections (abscesses, organ infections such as cholecystitis) may increase the time to be cured.

When should I contact a doctor about an E. coli infection?

Most people do not know they are infected by E. coli unless they are informed of an outbreak of E. coli. E. coli can be suggested by their symptoms during an outbreak or if they have ingested contaminated food or fluids. The ultimate diagnosis of E. coli infection is based on the isolation of the organism from the infected site. Consequently, individuals that suspect they have been infected with E. coli should contact a health care professional urgently. Bloody diarrhea, dehydration, high fevers, severe urinary problems, and mental status changes are conditions that could be due to various serious infections caused by E. coli and must be evaluated emergently.

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Medically Reviewed on 4/26/2019



Madappa, T. “Escherichia Coli (E. coli) Infections.” Medscape. Feb. 11, 2019. <https://emedicine.medscape.com/article/217485-overview>.