Foodborne E coli infection

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

Evidence last reviewed: 30 Mar 2026

Topic last updated: 23 Apr 2026

Foodborne Escherichia coliinfection most commonly 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 Shiga toxin-producing E coli (STEC), historically referred to as enterohemorrhagic E coli (EHEC), is O157:H7.

Approximately 5% to 10% 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 >65 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

suspected foodborne illness

ACUTE

confirmed enterotoxigenic positive

confirmed enterohemorrhagic positive

other Escherichia coli serotypes

Contributors

Authors

Eli D. Ehrenpreis, MD, FACG, AGAF

Reaserch Director

Internal Medicine Residency

Advocate Lutheran General Hospital

Park Ridge

Professor of Medicine

Wake Forest University Medical School

Winston-Salem

Disclosures

EDE is CEO, owner, and shareholder for E2Bio Life Sciences LLC. 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. EDE is the inventor and owner of patents for this device. EDE is also a CEO of G.I. Pharmaceuticals Inc., which has medical treatments for oral leukoplakia designed to prevent oral cancer, and a new medication for anal pruritus. G.I. Pharmaceuticals Inc. is involved with the development of educational programs for students and medical trainees.

Acknowledgements

Dr Eli D. Ehrenpreis would like to gratefully acknowledge the assistance of Dr Olivia Foy, who contributed to this update. Dr Eli D. Ehrenpreis would like to gratefully acknowledge Dr Olivia Foy, Dr Alexandra Kent, and the late Professor Satish Keshav, the previous contributors to this topic.

Disclosures

OF and AK 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.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

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

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 2026: health information for international travel: preparing international travelers - travelers' diarrhea. 2025 [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
- E. coli (Escherichia coli) infection
- Infectious diarrhea - guideline for investigation
More Guidelines
Patient information
Diarrhea in adults
Diarrhea in children
More Patient information
Log in or subscribe to access all of BMJ Best Practice

Use of this content is subject to our disclaimer

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

suspected foodborne illness

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

Peer reviewer acknowledgements

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