History and exam
Key diagnostic factors
common
diarrhea
Enteric infections with pathogenic Escherichia coli are characterized by diarrhea.
Enterotoxigenic E coli (ETEC) infection typically causes profuse watery diarrhea, while the Shiga-like toxin in enterohemorrhagic E coli (EHEC) causes bloody diarrhea and abdominal pain.[31]
history of travel, contact with contaminated food, or contact with infected person
Travel history should always be sought, as Escherichia coli is a common cause of traveler's diarrhea.[8]
Although the consumption of potentially contaminated food and/or water is an important part of the medical history, this information is unlikely to differentiate E coli infection from other causes of foodborne infection. A history of ingesting ground beef (e.g., in hamburgers) is important as there is a close association between ground beef and the O157:H7 subtype of E coli.[14] One meta-analysis found that beef was the most significant food item risk for acquiring shiga-toxin producing E coli infection in North America and Europe, while chicken was the most significant food item in the Western Pacific.[34]
A contact history should be sought in all patients as infection can spread due to fecal-oral contamination.
Other diagnostic factors
common
abdominal pain or discomfort
Common but nonspecific symptom, occurring with many foodborne infections.
volume depletion
Can manifest as dry mucous membranes, reduced skin turgor and, in severe cases, as tachycardia and hypotension.
uncommon
fever
Common with enteric and foodborne infections.
Rarely lasts beyond the first 2-3 days. Persistent high fever is concerning for bacteremia.
nausea/vomiting
E coli infections are infrequently associated with nausea. Vomiting is uncommon.
anorexia
E coli infection may be associated with additional gastrointestinal symptoms, such as anorexia.
lethargy
Systemic symptoms, including lethargy, may be present.
Risk factors
strong
ingestion of contaminated food products or water
Infection is related to exposure to contaminated food or water, and is more common in regions lacking adequate sanitation and clean water.
In the US, 52% of outbreaks of Escherichia coli O157:H7 have been associated with contaminated food, including ground beef (41%), produce (21%), other beef (6%), dairy products (4%), and unknown/other foods (28%).[14] E coli O157:H7 outbreaks have also been associated with spinach, romaine lettuce, unpasteurized milk, and infected food handlers.[14][15]
E coli has been found in up to 33% of ready-to-eat foods in developing countries.[28]
travel
Escherichia coli is the leading cause of traveler's diarrhea, with enterotoxigenic E coli (ETEC) being the cause of diarrheal episodes in up to 34% of people traveling in Latin America, Africa, and south and southeast Asia.[8]
Diffusely adherent E coli (DAEC) and enteroaggregative E coli (EAEC) are also causative agents of traveler's diarrhea. Diffusely adherent E coli (DAEC) is more commonly associated with children and people traveling in North Africa, Mexico, or South America. Studies have suggested it can accounts for 8% to 14% of cases of traveler's diarrhea.[17]
poor hygiene practices
The fecal-oral route of transmission accounts for 14% of Escherichia coli O157:H7 outbreaks.[14] The majority of these outbreaks have been reported in childcare facilities, however, person-to-person outbreaks have also occurred in individual residencies, communities, residential facilities, and schools.[14]
These outbreaks most often occur during summer months.[14]
infantile or advanced age (<5 years and >60 years)
Although foodborne Escherichia coli can affect all ages, complications are far more common in infants and older people. Hemolytic uremic syndrome and death are far more common in these age groups.[14]
Enteropathogenic E coli (EPEC) characteristically causes a diarrheal illness in young infants (ages <2 years).
contact history
Escherichia coli infections often occur in multi-patient outbreaks as a result of fecal-oral contamination; contact history should be sought in all patients.
weak
immunocompromised state
An immunocompromised state, whether due to underlying illness (e.g., cancer, HIV infection), poor nutrition, or immunosuppressive therapy, may increase a patient's susceptibility to Escherichia coli infections. In addition, E coli infections that are usually self-limited and short duration may cause prolonged illness in those who are immunocompromised.
contact with infected animals
There have been sporadic reports of pathogen transmission from contact with animals carrying Escherichia coli, including petting zoo animals, farm animals, and household pets.[20][21][22][23] However, incidence is low and transmission via this route is considered a weak risk factor for E coli infection.
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