Treatment of Shiga Toxin-Producing E. coli (STEC) Infections
Do not give antibiotics for STEC infections, particularly those producing Shiga toxin 2 or E. coli O157:H7, as they increase the risk of hemolytic uremic syndrome (HUS). 1, 2
Primary Treatment: Aggressive Fluid Management
Early and aggressive parenteral volume expansion is the only proven effective treatment and is crucial to prevent HUS development. 1, 2
Fluid Management Algorithm
For mild to moderate dehydration: Use reduced osmolarity oral rehydration solution (ORS) as first-line therapy 1, 2
For severe dehydration, shock, altered mental status, or ORS failure: Immediately administer isotonic intravenous fluids (lactated Ringer's or normal saline) 1, 2
Optimal fluid strategy (under investigation): Hyperhydration with 200% maintenance balanced crystalloid fluids targeting 10% weight gain and 20% hematocrit reduction may reduce major adverse kidney events, though this remains under study 3
Critical Monitoring Requirements
Close surveillance for HUS development is mandatory, particularly in children under 5 years who face the highest risk. 1, 2
Monitor specifically for the HUS triad: thrombocytopenia, hemolytic anemia, and renal failure 1, 2
Continue monitoring even after diarrhea resolves, as HUS can develop days after initial symptoms 2
Length of anuria exceeding 10 days and prolonged dialysis are the most important risk factors for poor acute and long-term renal outcomes 4
All patients must be followed for at least 5 years after the acute episode; severely affected patients require indefinite follow-up if proteinuria, hypertension, or reduced GFR develops 4
What NOT to Do: Critical Contraindications
Antibiotics Are Contraindicated
Antimicrobial therapy should be avoided in infections caused by STEC O157 and other STEC that produce Shiga toxin 2. 1
Multiple retrospective studies demonstrate higher rates of HUS in patients treated with antimicrobials 1
In vitro data indicate certain antimicrobial agents increase Shiga toxin production 1
Exception: For immunocompromised patients with severe illness and bloody diarrhea, empiric antibacterial treatment may be considered, but the risks of HUS development must be carefully weighed 1
Antimotility Agents Are Contraindicated
Antimotility agents should not be used in suspected or documented STEC infections as they may increase the risk of HUS. 1, 5
Renal Replacement Therapy
Approximately 73.6% of critically ill patients with STEC-HUS require renal replacement therapy during the acute phase 6
Most patients who progress to end-stage kidney disease do not recover normal renal function after the acute episode 4
However, with appropriate supportive care, no patients required renal replacement therapy 6 months after ICU admission in one large outbreak series 6
Diagnostic Considerations for Optimal Management
Prompt and accurate diagnosis enables appropriate supportive care and prevents inappropriate antibiotic use. 2
All stools from patients with acute community-acquired diarrhea should be simultaneously cultured for E. coli O157:H7 and tested with Shiga toxin assays 2
Testing should occur regardless of patient age, season, or presence of blood in stool 2
Specimens should be collected as soon as possible after diarrhea onset, while acutely ill, and before any antibiotic administration 2
Detection of O157 STEC within 24 hours helps physicians rapidly assess the patient's risk for severe disease and initiate measures to prevent serious complications 7
Special Populations and Considerations
Asymptomatic contacts of people with STEC infection should not receive antimicrobial therapy 1
Mortality rates are highest in patients over 60 years old, making early recognition and aggressive supportive care particularly critical in older adults 8
The acute mortality rate in children is 1-4%, with about 70% recovering completely from the acute episode 4
Public Health Reporting
All confirmed STEC cases must be reported to public health authorities for outbreak detection and control. 2
Food-service workers and childcare attendees may require negative follow-up cultures before returning to work/school per state regulations 2
Rapid isolation and subtyping of STEC isolates leads to prompt detection of outbreaks and timely public health actions 7
Long-Term Sequelae to Monitor
Renal sequelae: Proteinuria (15-30%), hypertension (5-15%), chronic kidney disease (9-18%), end-stage kidney disease (3%) 4
Extra-renal sequelae: Colonic strictures, cholelithiasis, diabetes mellitus, or brain injury (less common) 4
Severe neurological symptoms develop in approximately 66% of critically ill patients 6
Common Pitfalls to Avoid
Administering antibiotics for STEC O157 infections, which increases the risk of HUS 1
Failure to monitor for development of HUS, especially in high-risk populations such as children under 5 years 1
Inadequate fluid resuscitation in the early phase of illness 1, 2
Discontinuing monitoring too early—all patients require at least 5 years of follow-up 4