What is the treatment for a 22-year-old man with Shiga toxin-producing E. coli (STEC) infection, presenting with diarrhea, normal renal function, but elevated Blood Urea Nitrogen (BUN), White Blood Cell (WBC) elevation, and frequent bowel movements?

Treatment of Shiga Toxin-Producing E. coli Infection

Supportive care with careful fluid management and close monitoring is the recommended treatment for Shiga toxin-producing E. coli (STEC) diarrhea; antimicrobial therapy should be avoided as it may increase the risk of hemolytic uremic syndrome (HUS). 1

Initial Management

Fluid Resuscitation and Monitoring

• Assess for dehydration, which increases risk of life-threatening illness and death 1
• Use reduced osmolarity oral rehydration solution (ORS) as first-line therapy for mild to moderate dehydration 1
• For severe dehydration, administer isotonic IV fluids (lactated Ringer's or normal saline) 1
• Monitor vital signs and urine output closely

Laboratory Monitoring

• Frequent monitoring of:
  • Complete blood count (hemoglobin and platelet counts)
  • Electrolytes
  • Blood urea nitrogen (BUN) and creatinine
  • Peripheral blood smear for red blood cell fragmentation 1, 2

What NOT to Do

Avoid Antimicrobial Therapy

• Antimicrobial therapy for STEC O157 and other STEC that produce Shiga toxin 2 should be avoided 1
• Meta-analyses show antibiotics may increase risk of HUS development (OR 2.24,95% CI 1.45-3.46) in high-quality studies 3
• Antibiotics may induce bacterial cell lysis and release stored toxins 4
• Some antimicrobials may enhance toxin synthesis and production 4

Avoid Antidiarrheal Medications

• Antimotility agents like loperamide should be avoided in STEC infections 1
• These medications may increase risk of HUS by prolonging toxin exposure to intestinal mucosa 1

Monitoring for Complications

Signs of Developing HUS

• Monitor for early manifestations of HUS:
  • Decreasing platelet count trend (days 1-14 of illness)
  • Increasing creatinine level
  • Rising blood pressure
  • Signs of volume overload 1

When to Escalate Care

• Patients with signs of developing HUS should receive care in a center that can manage acute renal failure 1
• Daily monitoring can stop when platelet count begins to increase or stabilize in patients with resolved or resolving symptoms 1

Adjunctive Therapies

Probiotics

• Probiotic preparations may be offered to reduce symptom severity and duration in immunocompetent patients 1
• Most trials report probiotics decrease diarrhea duration and stool frequency 1

Follow-up Considerations

Return to Work/School

• For STEC infections, children are excluded from child care until diarrhea resolves
• Two stool cultures negative for the organism typically required for readmission 1
• Regular and consistent follow-up is recommended until laboratory and clinical parameters return to normal 1

Common Pitfalls to Avoid

1. Premature antibiotic use: Avoid antibiotics even with elevated WBC count, as this is common in STEC infections and not an indication for antimicrobial therapy 1, 5

2. Inadequate monitoring: Failure to monitor hemoglobin, platelets, and renal function may miss early signs of HUS development 1, 2

3. Inappropriate use of antidiarrheals: These can worsen outcomes in STEC infections 1

4. Delayed diagnosis: Early identification of STEC is crucial to prevent complications and person-to-person transmission 1

5. Inadequate hydration: Volume depletion is a risk factor for diarrhea-related deaths and increases need for dialysis in post-diarrheal HUS 1

The management of this 22-year-old man with Shiga toxin-producing E. coli diarrhea requires vigilant supportive care with close monitoring for HUS development, while avoiding potentially harmful interventions like antibiotics and antidiarrheal medications.