From the Guidelines
For patients presenting with diarrhea, I strongly recommend ordering a comprehensive stool panel that includes tests for bacterial pathogens, Clostridioides difficile, and parasites, as this approach is supported by the most recent and highest quality evidence 1. When evaluating diarrhea, it is essential to consider the patient's clinical presentation, duration of symptoms, travel history, and risk factors to guide the selection of stool tests.
- A stool culture should be performed to identify bacterial pathogens like Salmonella, Shigella, Campylobacter, and E. coli, as recommended by the 2017 Infectious Diseases Society of America clinical practice guidelines 1.
- A Clostridioides difficile toxin assay should be included, especially if the patient has recent antibiotic exposure or healthcare contact, due to the increased risk of C. difficile infection 1.
- A stool ova and parasite examination should be performed to detect parasitic infections such as Giardia and Entamoeba, as these pathogens can cause persistent diarrhea 1. Additionally, consider including a fecal occult blood test to check for intestinal bleeding and fecal calprotectin or lactoferrin to assess for inflammatory bowel disease, as these tests can help identify the underlying cause of diarrhea 1. For persistent diarrhea, consider adding tests for fecal fat (to evaluate malabsorption) and fecal elastase (to check pancreatic function), as these tests can help identify underlying conditions that may be contributing to the patient's symptoms. It is crucial to interpret the results of these tests in the context of the patient's clinical presentation and to consider the potential for colonization rather than infection, especially when using molecular diagnostic methods 1.
From the Research
Stool Tests for Diarrhea
To determine the appropriate stool test for diarrhea, several factors must be considered, including the patient's symptoms, medical history, and risk factors.
- The following pathogens are commonly associated with infectious diarrhea: Norovirus, Rotavirus, Campylobacter, Salmonella, Shigella, and pathogenic Escherichia coli 2, 3, 4.
- A rapid diagnostic workup should be performed in patients at risk, analyzing a single stool sample for Salmonella, Shigella, Campylobacter, and Norovirus 3.
- In patients with a history of antibiotic exposure within the last 3 months, testing for Clostridium difficile should be performed 3.
- Stool cultures for Campylobacter, Shigella, and Salmonella, as well as microscopic examination for amoebiasis and Giardiasis, may be necessary in certain cases, such as traveler's diarrhea with fever, bloody diarrhea, or severe clinical course 3.
Specific Testing Recommendations
- For patients with severe comorbidities, immunodeficiency, fever, or bloody diarrhea, empirical antibiotic treatment may be considered, and stool testing should be guided by the patient's clinical presentation 3.
- In children with persistent diarrhea or those who appear more toxic than their state of dehydration would suggest, testing for Salmonella, Shigella, and Campylobacter should be considered 4.
Limitations
There is no relevant information in the study from 1979 5 to assist in answering this question.