What is the recommended management for a patient with suspected Shiga‑toxin‑producing Escherichia coli infection?

Management of Shiga Toxin-Producing E. coli (STEC) Infection

Avoid antibiotics entirely in suspected or confirmed STEC infections, as they significantly increase the risk of hemolytic uremic syndrome (HUS), and instead provide aggressive intravenous fluid resuscitation as the cornerstone of management. 1, 2, 3, 4

Immediate Treatment Priorities

Fluid Management

• Initiate early parenteral volume expansion immediately upon diagnosis with isotonic intravenous fluids to prevent renal damage and HUS development. 1, 2
• Provide aggressive IV hydration based on severity of dehydration, particularly targeting correction of hypovolemia from bloody diarrheal episodes. 1, 2
• Correct hypokalemia with IV potassium supplementation, as severe diarrhea causes significant electrolyte losses requiring replacement. 2

Antibiotic Avoidance

• Do not administer antibiotics to patients with STEC infection, as meta-analysis of low-risk-of-bias studies demonstrates a clear association between antibiotic use and HUS development (OR 2.24,95% CI 1.45-3.46). 1, 3, 4
• Antibiotics may induce intestinal production of Shiga toxin during the diarrheal phase, worsening outcomes. 5
• In high-income countries, avoid empiric antibiotics for acute diarrhea until STEC infection has been excluded. 3

Medications to Avoid

• Do not use antimotility agents (e.g., loperamide), as they may prolong toxin exposure and worsen outcomes. 5

Diagnostic Approach

Specimen Collection

• Collect stool specimens as early as possible in the illness course, ideally before any antibiotic administration, while the patient is acutely ill. 6, 1
• Use diarrheal stool specimens; the same specimen collected for Salmonella, Shigella, and Campylobacter testing is acceptable. 6
• If rectal swabs must be used (particularly in children), broth enrichment is recommended as swabs may not contain sufficient stool. 6

Laboratory Testing Strategy

• All stools from patients with community-acquired diarrhea should be simultaneously cultured for O157 STEC and tested for non-O157 STEC with Shiga toxin detection assays. 6
• Perform Shiga toxin testing on growth from broth culture or primary isolation media rather than direct stool testing for improved sensitivity and specificity. 6
• Specimens should be processed immediately or refrigerated; do not hold unpreserved for >24 hours or in transport medium for >48 hours. 6

Specimen Forwarding

• Forward all O157 STEC isolates to public health laboratories as soon as possible for additional characterization. 6
• Forward all Shiga toxin-positive specimens or broths from which no STEC isolate was recovered to public health laboratories without delay. 6
• Ship as category A infectious substances per United Nations regulations (UN 2814) using appropriate packaging and documentation. 6

Monitoring for Complications

HUS Surveillance

• Monitor closely for development of HUS, particularly in children, characterized by thrombocytopenia, hemolytic anemia, and acute kidney injury. 1
• Approximately 5-10% of STEC-infected patients develop HUS, with children under 5 years at highest risk (approximately 8% of O157 STEC cases). 1, 5
• Strains producing Stx2 toxin (especially O157 STEC with stx2 and eae virulence genes) carry the highest risk for severe disease and HUS. 1

High-Risk Features

• Severe bloody diarrhea with >14 episodes daily indicates significant toxin exposure and increased HUS risk. 2
• Family history of HUS suggests genetic susceptibility or shared exposure to high-virulence STEC strain. 2
• Children aged <5 years have the highest incidence and greatest HUS risk. 1

Special Population Considerations

Pediatric Patients

• Children under 5 years require particularly aggressive monitoring and early IV hydration. 1
• Approximately 10% of children who develop HUS will die or have permanent renal failure, and up to 50% will develop some degree of renal impairment. 5

High-Risk Adults

• Elderly individuals and immunocompromised patients require more aggressive monitoring and supportive care. 1
• These populations may require longer observation periods due to potential for more severe disease. 7

Infection Control and Public Health

Hospital Precautions

• Implement contact precautions immediately for all suspected or confirmed STEC cases. 2
• Notify public health authorities promptly, as STEC is a reportable infection requiring outbreak investigation. 2

Household Contacts

• Do not treat asymptomatic household contacts empirically with antibiotics. 2
• Advise household contacts on proper hand hygiene and infection prevention measures. 2
• Certain persons (food-service workers, childcare attendees/workers) may be required by state law to prove they are no longer shedding bacteria before returning to work. 6

Critical Pitfalls to Avoid

• Never administer antibiotics empirically for bloody diarrhea before excluding STEC infection. 3, 4
• Do not use antimotility agents, which may prolong toxin exposure. 5
• Do not delay specimen collection or testing, as diagnostic sensitivity decreases later in illness. 6, 1
• Do not ship specimens improperly; STEC cultures are category A infectious substances requiring specific packaging and training. 6
• Do not interpret negative cultures as excluding STEC if Shiga toxin testing is positive; forward specimens to public health laboratories for further isolation attempts. 6