Foodborne E coli infection

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 16 May 2025

Last updated: 08 Feb 2024

Foodborne Escherichia coli infection typically occurs through the ingestion of food or water contaminated with pathogenic strains of E coli.

Enterotoxigenic E coli (ETEC) is the most common cause of traveler's diarrhea.

Diagnosis is made based on stool culture, with serotyping for greater specificity.

Treatment is supportive, with rehydration and correction of electrolyte imbalance.

Use of antibiotics is controversial and in most cases not necessary, except possibly in traveler's diarrhea.

In the US, the most common serotype of enterohemorrhagic E coli (EHEC) is O157:H7.

Ten percent of patients with E coli O157:H7 infection develop hemolytic uremic syndrome.

Definition

E coli is a gram-negative, rod-shaped bacterium. It is a commensal organism that colonizes the gastrointestinal tract within a few hours of birth. E coli becomes pathogenic by acquiring virulence factors or genetic mutations. Infection by pathogenic strains occurs through ingestion, usually via contaminated food or water.

History and exam

Key diagnostic factors

diarrhea
history of travel, contact with contaminated food, or contact with infected person

Full details

Other diagnostic factors

abdominal pain or discomfort
volume depletion
fever
nausea/vomiting
anorexia
lethargy

Full details

Risk factors

ingestion of contaminated food products or water
travel
poor hygiene practices
infantile or advanced age (<5 years and >60 years)
contact history
immunocompromised state
contact with infected animals

Full details

Diagnostic tests

1st tests to order

stool cultures
CBC
renal function and electrolytes

Full details

Tests to consider

identification of Shiga toxin-producing E coli infection
blood cultures
inflammatory markers (CRP and/or erythrocyte sedimentation rate)
abdominal x-ray
endoscopy
abdominal CT scan

Full details

Treatment algorithm

INITIAL

all patients

ACUTE

confirmed enterotoxigenic positive

confirmed enterohemorrhagic positive

other Escherichia coli serotypes

Contributors

Authors

Eli D. Ehrenpreis, MD, FACG, AGAF

Associate Director for Research

Internal Medicine Residency

Advocate Lutheran General Hospital

Park Ridge

Disclosures

EDE is a CEO for E2Bio Life Sciences LLC and G.I. Pharmaceuticals Inc. E2Bio Life Sciences LLC has developed Bocaliner, an FDA-registered class 1 medical device designed to enhance the efficacy of topical medications applied to the oral cavity. G.I. Pharmaceuticals Inc. has medical treatments for oral leukoplakia designed to prevent oral cancer, and a new medication for anal pruritis.

Acknowledgements

Dr Eli D. Ehrenpreis would like to gratefully acknowledge the assistance of Dr Thomas Adam Wichelmann, who contributed to this update. Dr Ehrenpreis would also like to acknowledge Dr Alexandra Kent and Professor Satis Keshav, the previous contributors to this topic.

Disclosures

TAW, AK, and SK declare that they have no competing interests.

Peer reviewers

Andrew Poullis, BSc, MBBS, MD, FRCP

Consultant Gastroenterologist

St George’s Hospital

London

Disclosures

AP declares that he has no competing interests.

Fiona Cooke, MA, PhD, MSc, FRCPath, MRCP, DTM&H

Research Fellow and Medical Microbiologist

Wellcome Trust Sanger Institute

Department of Microbiology

Addenbrooke's Hospital

Cambridge

Disclosures

FC declares that she has no competing interests.

Houssam E. Mardini, MD, MPH, FACP

Voluntary Assistant Professor of Medicine

Digestive Health & Nutrition Center of Ashland

Ashland

Disclosures

HEM declares that he has no competing interests.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Nataro JP, Kaper JB. Diarrheagenic Escherichia coli. Clin Microbiol Rev. 1998 Jan;11(1):142-201.Full text Abstract

Kaper JB, Nataro JP, Mobley HL. Pathogenic Escherichia coli. Nat Rev Microbiol. 2004 Feb;2(2):123-40.Full text Abstract

American Medical Association; American Nurses Association-American Nurses Foundation; Centers for Disease Control and Prevention; Center for Food Safety and Applied Nutrition, Food and Drug Administration; Food Safety and Inspection Service, US Department of Agriculture. Diagnosis and management of foodborne illnesses: a primer for physicians and other health care professionals. MMWR Recomm Rep. 2004 Apr 16;53(RR-4):1-33.Full text Abstract

Shane AL, Mody RK, Crump JA, et al. 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea. Clin Infect Dis. 2017 Nov 29;65(12):e45-80.Full text Abstract

Centers for Disease Control and Prevention. CDC Yellow Book 2024: health information for international travel. Section 2: preparing international travelers - travelers' diarrhea. May 2023 [internet publication].Full text

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials
- Viral gastroenteritis
- Alternative foodborne bacterial gastroenteritis/traveler's diarrhea
- Amebiasis
More Differentials
Guidelines
- Infectious diarrhea - guideline for investigation
- E. coli (Escherichia coli) infection
More Guidelines
Patient information
Diarrhea in adults
Diarrhea in children
More Patient information
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Foodborne E coli infection

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic tests

1st tests to order

Tests to consider

Treatment algorithm

all patients

confirmed enterotoxigenic positive

confirmed enterohemorrhagic positive

other Escherichia coli serotypes

Contributors

Authors

Eli D. Ehrenpreis, MD, FACG, AGAF

Disclosures

Acknowledgements

Disclosures

Peer reviewers

Andrew Poullis, BSc, MBBS, MD, FRCP

Disclosures

Fiona Cooke, MA, PhD, MSc, FRCPath, MRCP, DTM&H

Disclosures

Houssam E. Mardini, MD, MPH, FACP

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials

Guidelines

Patient information

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice