From the Guidelines
For patients presenting with acute diarrhea, stool studies are indicated to identify the underlying cause, particularly if symptoms persist or are accompanied by bloody stools, fever, or severe abdominal pain.
Recommended Stool Studies
- A stool culture for bacterial pathogens, such as Salmonella, Shigella, and Campylobacter, should be performed 1
- A stool ova and parasite examination to detect parasitic infections should also be considered
- A stool test for Clostridioides difficile (C. diff) toxin should be considered, especially in patients who have recently received antibiotic therapy, such as clindamycin or fluoroquinolones, within the past 8 weeks 1
Additional Considerations
- Yersinia enterocolitica testing should be considered in people with persistent abdominal pain, especially school-aged children with right lower quadrant pain mimicking appendicitis 1
- Vibrio species testing should be considered in people with large volume rice water stools or exposure to salty or brackish waters, consumption of raw or undercooked shellfish, or travel to cholera-endemic regions within 3 days prior to onset of diarrhea 1
- A broader set of bacterial, viral, and parasitic agents should be considered in immunocompromised people with diarrhea, especially those with moderate and severe primary or secondary immune deficiencies 1
From the Research
Stool Studies for Acute Diarrhea
The following stool studies are indicated for acute diarrhea:
- Stool multiplex polymerase chain reaction (PCR) tests to identify diarrhea-causing bacterial pathogens 2, 3
- Fecal calprotectin to detect intestinal mucosal inflammation 2
- Stool culture to detect pathogenic bacteria, although its diagnostic yield is low 4
- Rapid tests for bacterial, viral, or protozoal infections 5
- Glutamate dehydrogenase test for Clostridioides difficile infection, followed by specialized nucleic acid amplification test or enzyme immunoassays for toxin A or B to distinguish infection from carrier state 5
Indications for Stool Testing
Stool tests are indicated in acute diarrhea when:
- There is a strong pretest probability of infectious etiology or Clostridioides difficile infection 5
- Symptoms include more than 3 unformed bowel movements per 24 hours, lasting more than 7 days, and circumstances suggestive of infection 5
- Patients have fevers, longer hospital length of stay, or other severe symptoms 4