This case study focuses on the outbreaks of e coli food poisoning similar to those at the Chipotle Mexican Grill which have been in the news recently.  With medical algorithms, healthcare providers can quickly distinguish which foodborne illness the patient has and help identify its cause.


Mary is a grandmother with three grandchildren. On Saturday she took them shopping and afterwards they went to their favorite taco restaurant.

On Tuesday Mary felt a little sick when she woke up with some abdominal cramping. Her grandchildren also felt too sick to go to school. Their parents felt fine and the father stayed home to watch the children. Later that day, everyone who had eaten at the taco restaurant developed diarrhea. That evening Mary noticed that her stool was bloody. She developed fever, fatigue, bruising and decreased urine output.

Her daughter took Mary to the Emergency Room early Wednesday morning. Her serum creatinine concentration was high and her platelet count was low. A peripheral blood smear showed numerous schistocytes without platelet clumping. She was admitted to the hospital and started on hemodialysis that afternoon.

The stool culture was positive for Escherichia coli. The isolate was positive for Shiga toxin. A diagnosis of Shiga-toxin producing E. coli (STEC) was made.

Mary was in the hospital for 2 weeks and was discharged home. Recuperation was slow but she gradually recovered without residua.

During her hospitalization, the State Health Department completed an investigation of the restaurant and was unable to find an identifiable source. The restaurant (and its sister locations in the same city) were closed for terminal cleaning and re-opened after no source was found and additional preventive measures were taken.


Shiga-toxin e Coli Poisoning Symptoms & Causes

Shiga-toxin producing Escherichia coli (STEC) can be acquired in several ways, but usually it is acquired from contaminated food. Possible sources include ground beef, poultry, sprouts, cucumbers, lettuce, and other produce. Produce from a single contaminated site may be transported large distances, resulting in multi-state outbreaks.

Risk Factors for Transmission of Escherichia coli (E. coli)

An infection often presents as a diarrheal disease which must to be distinguished from other food-borne diseases (Salmonella, Shigella, Listeria, Campylobacter, etc). This usually involves stool testing for both bacteria and Shiga toxin.

Clinical and Laboratory Features of Shiga Toxin Producing E. Coli (STEC)

Patient Testing for Shiga Toxin-Producing E. coli (STEC)

What makes STEC of concern is that some patients develop hemolytic-uremic syndrome (HUS). This is a much more serious condition which can result in renal and multiple organ failure. HUS overlaps with Thrombotic Thrombocytopenic Purpura (TTP).

Risk Factors for Hemolytic Uremic Syndrome (HUS) in a Patient Infected with E. coli

Clinical Severity Scoring System for TTP or HUS

HUS or TTP are syndromes that can have multiple causes. Management involves identifying the cause so that specific therapy can be initiated in addition to management of organ failures.

Conditions Associated with Thrombotic Thrombocytopenic Purpura (TTP)

HIV-Related Thrombotic Thrombocytopenic Purpura (TTP) and Hemolytic Uremic Syndrome (HUS)

Hemolytic Uremic Syndrome (HUS) in Children Associated with Invasive Streptococcus pneumoniae (Streptococcus pneumoniae-Associated Hemolytic Uremic Syndrome, SP-HUS)

With modern therapy most patients can be successfully treated. Some patients may have prolonged admissions to the intensive care unit. Fatalities can occur in vulnerable patients, patients with delayed care, or fulminant disease. Medical algorithms can help to identify high risk patients who may benefit from more aggressive management.

Criteria for Resolution of Hemolytic Uremic Syndrome (HUS) Caused By Shiga Toxin-Producing Escherichia coli

e coli Prevention

Prevention of STEC infection can be challenging, especially for restaurants. Produce should be carefully cleaned and workers trained in proper food preparation. Meat products should be thoroughly cooked based on internal temperature.

Beef Temperature and How Well Cooked It Is

If a case is identified then it is important for food suppliers, restaurants and local health departments to work together to find the source so that further cases can be avoided.

Take-Home Points

  • While STEC may be rare, foodborne illness and gastroenteritis is quite common. A powerful algorithm assists physicians in the identification of both common and uncommon pathogens.
  • Combining medical training with powerful, evidence-based algorithms can help physicians diagnose, assess, and manage diseases.

The medical algorithms highlighted in this case study are available at The Medical Algorithms Company and also on the apervita health analytics platform.

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About the Authors

Umang Jain is the Health Innovations Fellow at Apervita. He is passionate about medicine, research, and business. He is a fourth year medical student at Northwestern University’s Feinberg School of Medicine and will pursue Emergency Medicine residency. Umang’s scholarly interests include surgical outcomes research, in which he is published in the fields of ENT, orthopedic, plastic, cardiac, and urologic surgery. He has also participated in research in neurodegenerative disease at MIT and Boston University. Umang’s business experience stems from his work at the Institute of Healthcare Improvement (IHI) in Boston, MA. He worked closely with Dr. Donald Berwick, Administrator of Medicare and Medicaid Services (CMS) and Sir Nigel Crisp, the former Chief Executive of UK’s National Health Service, on engaging in evidence-based healthcare improvement interventions on a global scale. Umang was also an intern at Senticare Inc. and Personica, where he evaluated EHRs and in-home health monitoring equipment.

Dr. Chad Rudnick, MD, FAAP is a board-certified pediatrician in Boca Raton, FL. He is the Medical Director of The Medical Algorithms Company. A proponent of incorporating medical technology into his practice, Dr. Rudnick uses telemedicine and medical algorithms from The Medical Algorithms Company in his daily practice to better serve his patients and their families. An accomplished medical writer, he maintains a popular pediatric blog, All Things Pediatric, and has written for numerous online and print publications including

John Svirbely, MD is a founder and Chief Medical Officer of The Medical Algorithms Company and the primary author of its medical algorithms. John is a co-founder of the Medical Algorithms Project and has developed its medical content for nearly 20 years. He has a BA degree from the Johns Hopkins University and his MD from the University of Maryland. He is a board-certified pathologist with a fellowship in medical microbiology and biomedical computing at Ohio State University. Currently he is in private practice in Cincinnati, Ohio. He has authored multiple books and articles on medical algorithms.