Every year, about 2.2 million deaths occur worldwide due to diarrhea. Reliable diagnosis of patients with acute infectious diarrhea remains a formidable challenge to the clinicians. This is the first study reporting use of fecal calprotectin in diagnosing acute diarrhea. The aim was to compare the diagnostic accuracy of fecal calprotectin, fecal lactoferrin, and guaiac-based fecal occult blood test in a diverse group of consecutive patients with acute diarrhea in which routine bacterial stool cultures and cytotoxins for Clostridium difficile were performed.

This was a prospective case-control multicenter study from January 2004 until October 2007 in 2383 consecutive patients with acute diarrhea. They provided stool samples for performing cultures. Patients with positive cultures and an equal number of matched controls with negative cultures underwent fecal occult blood test and calprotectin and lactoferrin assays.

Calprotectin, lactoferrin, and fecal occult blood tests demonstrated sensitivity and specificity of 83% and 87%, 78% and 54%, and 38% and 85%, respectively, for diagnosing acute bacterial diarrhea.

Calprotectin showed high correlation with bacteriologically positive infectious diarrhea compared with lactoferrin and fecal occult blood test. It may potentially revolutionize management algorithm for patients with acute diarrhea. As a screening test, calprotectin can generate results within hours to support presumptive diagnosis of infectious diarrhea, which can decide suitability of stool samples for culture.