Fecal Calprotectin is NOT Recommended for Acute STEC Infection Management
Do not use fecal calprotectin to guide management decisions in acute Shiga toxin-producing E. coli (STEC) infections. The 2017 Infectious Diseases Society of America (IDSA) guidelines explicitly state there are insufficient data to recommend fecal calprotectin measurement in people with acute infectious diarrhea 1. This applies directly to STEC infections.
Why Calprotectin Has No Role in STEC Management
Limited Evidence in Acute Infectious Diarrhea
The IDSA guidelines found conflicting and limited reports about fecal calprotectin's value in acute infectious diarrhea, with some studies suggesting higher levels may indicate bacterial etiologies while others found no diagnostic value 1.
Fecal calprotectin is elevated in various inflammatory conditions including infectious gastroenteritis, making it non-specific for distinguishing STEC from other causes of acute diarrhea 2, 3.
The marker cannot differentiate between bacterial pathogens or guide specific treatment decisions in the acute infectious setting 1.
Focus on Critical STEC-Specific Monitoring
Instead of calprotectin, the IDSA strongly recommends frequent monitoring of hemoglobin, platelet counts, electrolytes, blood urea nitrogen, and creatinine to detect early manifestations of hemolytic uremic syndrome (HUS) in patients with diagnosed STEC infection 1. This is a strong recommendation based on high-quality evidence.
Examining a peripheral blood smear for red blood cell fragmentation is necessary when HUS is suspected 1.
This monitoring is especially critical for STEC producing Shiga toxin 2 or infections associated with bloody diarrhea 1.
Clinical Pitfalls to Avoid
Do not delay appropriate supportive care or HUS monitoring while waiting for calprotectin results in suspected STEC infection 1.
Antimicrobial therapy is contraindicated in STEC infections as it may increase Shiga toxin production and HUS risk 4, 5.
Serologic testing for STEC may be considered only for post-diarrheal HUS when stool culture did not yield a Shiga toxin-producing organism, but this is a weak recommendation 1.
When Calprotectin IS Useful (Not in STEC)
Fecal calprotectin has established utility in inflammatory bowel disease (IBD) for diagnosing, monitoring disease activity, and guiding treatment adjustments, with cutoffs >150 μg/g indicating active inflammation 1, 2. However, this application is entirely separate from acute infectious diarrhea management 1.