Why are antibiotics generally avoided in suspected EHEC O157:H7 infections?

• A. They may increase risk of hemolytic uremic syndrome
• B. They are generally ineffective in preventing complications
• C. They can cause worsening kidney injury due to dehydration
• D. They may increase risk of antibiotic-associated diarrhea

Answer: (D)

Avoiding antibiotics in suspected EHEC O157:H7 is mainly about toxin-related risk. Killing the bacteria can trigger lysis and release of Shiga toxin, which mediates vascular injury and can lead to hemolytic uremic syndrome (HUS), a serious kidney-threatening complication, especially in children. Since HUS is driven by the toxin rather than by the infection itself, antibiotics do not improve outcomes and may worsen them by increasing toxin release. Instead, management is supportive—fluids, electrolyte balance, and monitoring—with renal support if needed. The concern about antibiotic-associated diarrhea exists with antibiotics in general, but the key reason here is the potential for increased Shiga toxin and HUS risk.