There are two types of diarrhea: infectious and non-infectious. Infectious diarrhea is caused by various bacteria, viruses, and parasites. Based on duration, diarrhea can be classified as acute (<14 days) or chronic/persistent (>14 days).
The most common microorganisms causing acute diarrhea include:
Viruses: Norovirus, Rotavirus, Adenovirus, Sapovirus, Astrovirus
Bacteria: Salmonella spp., Shigella spp., Campylobacter spp., E. coli strains (EIEC, EPEC, ETEC, EHEC O157:H7)
Others: Yersinia spp., Vibrio spp., Entamoeba histolytica
When should laboratory tests be performed for diarrhea?
Acute diarrhea is often viral in origin and usually resolves on its own, so initial testing is not always necessary. However, stool testing is recommended in the following cases:
1. Severe symptoms:
Prolonged diarrhea
Bloody diarrhea
Diarrhea associated with systemic illness
2. Patient history:
Weakened immune system
Recent international travel (suspected traveler's diarrhea)
Hospitalized patients
3. Need to identify the infectious agent
Which laboratory tests are used for diagnosing diarrhea?
Stool culture + antibiotic sensitivity: This is the gold standard for identifying Salmonella spp. and Shigella spp. through routine stool cultures.
Multiplex PCR (KBI PCR): A rapid and comprehensive test that detects the most common viral and bacterial pathogens (e.g., Norovirus, Rotavirus, Adenovirus, Astrovirus, Salmonella spp., Shigella spp., Campylobacter spp., E. coli) from a single stool sample.
Stool microscopy: Used for initial detection of Entamoeba histolytica, the parasite known for causing amoebic dysentery. Confirmation is done through antigen tests.
If symptoms persist or worsen, consulting a gastroenterologist and undergoing appropriate tests is essential for accurate diagnosis and treatment.