Final answer:
Medical practitioners use stool samples to diagnose causes of gastrointestinal symptoms by conducting microscopic examinations and using serological and molecular techniques. These tests can detect infectious agents and blood, indicating certain types of infections, which are crucial for determining the appropriate treatment.
Step-by-step explanation:
When a patient presents symptoms such as chronic diarrhea, medical practitioners may use a combination of clinical history and laboratory testing to diagnose the underlying cause. In the case of Ms. Schilling, her physician is looking for clues in her stool samples that might indicate the presence of infectious agents or blood, which can signal types of infections like Campylobacter jejuni, Salmonella, and Entamoeba histolytica. A microscopic examination of stool is often conducted over several days (at least 7 ideally), which can reveal presence of bacteria, cysts, and other organisms. Specific tests such as serological or molecular techniques, like immunoassays for S. dysenteriae, PCR testing, and stool O&P (ova and parasites) exam, are utilized to determine the cause of the symptoms and inform treatment decisions. In severe cases, antibiotics like ciprofloxacin and azithromycin may be prescribed.
Stool samples should be processed promptly to get the most accurate results. Factors like the patient's food ingestion history, as mentioned in the case of Carli, who consumed possibly undercooked eggs, are also taken into consideration when forming a hypothesis for the cause of the gastrointestinal distress. Blood tests accompanying stool analyses can also offer additional insight into the patient's health status and the severity of the infection.