What is the role of stool testing in the workup of pediatric hemolytic uremic syndrome (HUS)?

Updated: Nov 12, 2018
  • Author: Robert S Gillespie, MD, MPH; Chief Editor: Craig B Langman, MD  more...
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Answer

Usually, culture yield is low after 7 days of diarrhea. The standard method used to detect and isolate STEC involves sorbitol MacConkey (SMAC) agar plates that enable identification of characteristic sorbitol nonfermenting colonies of STEC O157:H7. E coli 0157:H7 does not grow on agar plates used for routine stool cultures. Notify the laboratory and request specific testing for this organism when hemolytic-uremic syndrome is suspected. Even patients with documented bloody diarrhea and other classic features of STEC-HUS often do not yield a causative organism on stool culture. This reflects the limited sensitivity of stool culture, not the absence of disease. The diagnosis of hemolytic-uremic syndrome is a clinical one and is not excluded by a negative stool culture.

Stx may be detected using specific antibody testing, gene studies, and enzyme-linked immunosorbent assay (ELISA).

Stool leukocytes have little value in detecting E coli 0157:H7. They are absent in approximately 50% of cases.


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