Today I review EM Quick Hits 63‘s* pediatric bloody diarrhea, S-TEC and hemolytic uremic syndrome.
*Helman, A. Freedman, S. Morgenstern, J. McArther, M. Petrosoniak, A. Long, B. Gotlieb, M. EM Quick Hits 63 – S-TEC and HUS, IM Epinephrine in OHCA, Dengue, Geriatric Trauma Imaging, TTP. Emergency Medicine Cases. March, 2025. https://emergencymedicinecases.com/em-quick-hits-march-2025/. Accessed May 4, 2025.
All that follows is from the above resource.
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Pediatric bloody diarrhea: Shiga Toxin Producing E. Coli (S-TEC) and HUS
Consider obtaining a stool specimen or rectal swab in the ED for PCR testing (not culture) to detect S-TEC, Salmonella, Shigella, and Campylobacter.
Which children with bloody diarrhea require bloodwork? Most children with blood in stool do not require blood work. Indications for bloodwork include:
- Hemodynamic instability
- S-TEC is high on your differential (bloodwork may be useful as baseline)
- Recent travel with bloody diarrhea and fever
- Close contact with S-TEC cases (~10% household transmission rate)
When to suspect S-TEC?
- Severe crampy abdominal pain
- >15-20 small frequent, mucousy, bloody stools per day
- Low grade fever
- Signs of microangiopathy (e.g. petechiae, jaundice)
- Endemic area
Children generally do not require stool O&P for acute diarrhea but should be considered for chronic abdominal pain, chronic diarrhea, or failure to thrive.
When to test for C.difficile? There is a high carriage rate of C. diff (up to ~50% in children under 2 years old). Consider C. diff testing only in children with risk factors such as recent antibiotic use or hospitalization, or as a second line test on follow up if bloody diarrhea persists that is not noted to be from another bacterial etiology.
Why is it important to recognize S-TEC?
A complication of S-TEC infection is Hemolytic Uremic Syndrome (HUS), caused by Shiga toxin accumulation in the kidney which leads to the HUS triad: acute kidney injury, hemolysis, and thrombocytopenia.
- Shiga toxin 2 (STX2) is specifically associated with a 15-20% risk of HUS in children <5 years
- HUS development increases risk of dialysis to 50-60% within 1 week
- Differentiating between STX1 (<1% risk of HUS) and STX2 toxin can help risk-stratify patients
How to risk stratify a positive STEC result:
- Assume blood in stool to be STX2 producing STEC until proven otherwise (non-bloody STEC unlikely making Shiga toxin 2 and unlikely to cause HUS)
- Determine duration of diarrhea: HUS develops a median of 7 days after diarrhea onset
- Diarrhea >10 days = low risk of HUS
- Determining if toxin result is STX2+ (high risk)
How to manage high risk patients with confirmed S-TEC?
- Manage dehydration aggressively (volume depletion is associated with adverse outcomes in HUS)
- Blood work q24h until reaching termination criteria (to allow early identification of microangiopathy)
- Platelet drop is the earliest marker of evolving HUS
- Consider LDH to identify hemolysis
Bottom line: Obtain early stool testing to identify children who present with bloody diarrhea for STEC, as some are at high risk of developing complications such as HUS. Children with STEC and their hydration status should be closely monitored.
- Freedman SB, van de Kar NCAJ, Tarr PI. Shiga Toxin-Producing Escherichia coli and the Hemolytic-Uremic Syndrome. N Engl J Med. 2023 Oct 12;389(15):1402-1414. doi: 10.1056/NEJMra2108739. PMID: 37819955.
- Allen UD; Canadian Paediatric Society, Infectious Diseases and Immunization Committee. Clostridium difficile in paediatric populations. Paediatr Child Health. 2014 Jan;19(1):43-54. PMID: 24627655; PMCID: PMC3938221.
- McKee RS, et al; Pediatric Emergency Medicine Collaborative Research Committee and Pediatric Emergency Research Canada. Predicting Hemolytic Uremic Syndrome and Renal Replacement Therapy in Shiga Toxin-producing Escherichia coli-infected Children. Clin Infect Dis. 2020 Apr 10;70(8):1643-1651. doi: 10.1093/cid/ciz432. PMID: 31125419; PMCID: PMC7931832.
