What is the treatment for a patient with positive Shiga toxin-producing Escherichia coli (E. coli) on stool Polymerase Chain Reaction (PCR) test, presenting with chronic diarrhea?

From the Guidelines

For a patient with Shiga toxin-producing E. coli (STEC) infection, antimicrobial therapy should be avoided, as it may increase the risk of hemolytic uremic syndrome (HUS) 1. The patient's symptoms of 3 weeks of water, orange-colored diarrhea, and positive stool PCR test for STEC, indicate that supportive care is the recommended approach. Key aspects of management include:

• Providing adequate hydration with oral rehydration solutions or IV fluids if needed
• Managing symptoms with anti-diarrheals only after ruling out inflammatory conditions
• Monitoring the patient closely for signs of HUS, such as decreased urine output, unusual bleeding, or neurological changes, particularly in the first 1-2 weeks after symptom onset 1
• Ensuring the patient maintains good hand hygiene and food safety practices to prevent transmission to others
• Advising the patient to avoid preparing food for others until diarrhea resolves and follow-up stool testing confirms clearance of the infection
• Informing the patient that most STEC infections resolve within 5-10 days with supportive management alone, though the orange-colored diarrhea may persist for some time before normalizing. It is essential to note that empiric antimicrobial therapy is not recommended for immunocompetent adults with STEC infections, except in specific circumstances, such as severe illness or immunocompromised status 1.

From the Research

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

• The treatment of STEC infection is primarily supportive, focusing on managing symptoms and preventing complications 2.
• Antibiotic treatment is generally not recommended for STEC infection, as it may increase the risk of developing hemolytic uremic syndrome (HUS) 2, 3.
• However, a study published in 2012 found that azithromycin treatment was associated with a lower frequency of long-term STEC carriage, but this finding is not directly applicable to the treatment of STEC infection 4.

Management of STEC Infection

• Supportive care, including aggressive hydration and monitoring for signs of HUS, is the mainstay of treatment 3.
• The use of interventions such as anti-Shiga toxin monoclonal antibodies, Shiga toxin binding protein, and bovine colostrum containing Shiga toxin antibodies has been investigated, but the evidence is limited and inconclusive 3.
• A 2025 review of interventions for preventing diarrhoea-associated HUS found that the current evidence is uncertain and that additional studies are needed to assess the benefits and harms of these interventions 3.

Diagnosis and Follow-up

• STEC stool multiplex PCR can be used for clinical diagnosis and follow-up, and may replace culture for these purposes 5.
• The majority of PCR-positive samples are also culture positive, and two consecutive PCR-negative samples may be sufficient to demonstrate clearance from STEC infection 5.