From the Guidelines
For patients with acute gastroenteritis, stool testing should be performed for Salmonella, Shigella, Campylobacter, Yersinia, C. difficile, and STEC in people with diarrhea accompanied by fever, bloody or mucoid stools, severe abdominal cramping or tenderness, or signs of sepsis 1. When evaluating a patient with acute gastroenteritis, it is essential to consider the clinical presentation and epidemiologic factors to determine the need for laboratory testing.
- The patient's symptoms, such as fever, bloody or mucoid stools, and severe abdominal cramping, can guide the decision to order stool studies.
- Additionally, certain patient populations, including infants <3 months of age, people with signs of septicemia, immunocompromised individuals, and those with high-risk conditions, may require blood cultures 1.
- Stool testing for specific pathogens, such as Yersinia enterocolitica, Vibrio species, and Clostridioides difficile toxin, may be warranted in certain situations, including persistent abdominal pain, exposure to raw or undercooked pork products, or recent antibiotic use 1.
- In cases where an outbreak is suspected, a broader set of bacterial, viral, and parasitic agents should be considered, and selection of agents for testing should be based on host and epidemiologic risk factors 1.
- The interpretation of results from multiplex polymerase chain reaction (PCR) assays, such as those used to detect gastrointestinal pathogens, should take into account the clinical context and the potential for false-positive results 1.
- It is also important to note that laboratory testing is not recommended for most cases of uncomplicated traveler's diarrhea, unless treatment is indicated or the patient has been treated with antimicrobial agents within the preceding 8-12 weeks 1.
From the Research
Lab Tests for Acute Gastroenteritis
The following lab tests may be ordered for acute gastroenteritis:
- Stool culture to identify bacterial causes 2
- Viral antigen tests to identify viral causes 3
- PCR-based multiplex gastrointestinal (GI) pathogen panels for rapid and accurate diagnosis 2
- Fecal biomarkers such as lactoferrin, fecal leukocyte analysis, and calprotectin to assess intestinal inflammation 4
- Systemic biomarkers such as C-reactive protein, erythrocyte sedimentation rate, and serum cytokines to assess the host response to infection 4
Considerations for Lab Test Ordering
When ordering lab tests for acute gastroenteritis, consider the following:
- The patient's clinical presentation, such as the presence of blood or mucus in the stool, vomiting, or abdominal pain 3
- The patient's age and immune status, as certain populations may be at higher risk for specific causes of gastroenteritis 5, 6
- The potential for antibiotic use and the need for targeted therapy 2
Reduction of Unnecessary Testing
The use of multiplex PCR stool testing has been associated with a reduction in the utilization of endoscopy, abdominal radiology, and antibiotic prescribing 2