There has been an outbreak of food born salmonella gastroenteritis in the community and the stool samples have been received in the laboratory. Which is the enrichment medium of choice-
**Core Concept**
The question is testing the student's knowledge of the appropriate enrichment medium for isolating Salmonella species from stool samples. Enrichment media are used to promote the growth of specific microorganisms while inhibiting the growth of others, allowing for the selective isolation of pathogens.
**Why the Correct Answer is Right**
The correct answer is **C. Selenite F broth**. Selenite F broth is a selective enrichment medium used for the isolation of Salmonella species. The presence of sodium selenite in the medium inhibits the growth of other enteric bacteria while allowing Salmonella to grow. The selenite also enhances the expression of the Salmonella's flagella, making it easier to detect using a flagellar stain.
**Why Each Wrong Option is Incorrect**
* **Option A:** is incorrect because it does not specify a medium commonly used for Salmonella isolation. While other media may be used for other pathogens, Selenite F broth is the preferred choice for Salmonella.
* **Option B:** is incorrect because it is not a specific enrichment medium for Salmonella. While it may be used in some capacity, it is not the preferred choice for Salmonella isolation.
* **Option D:** is incorrect because it is not a commonly used enrichment medium for Salmonella. While it may be used for other pathogens, it is not the preferred choice for Salmonella.
**Clinical Pearl / High-Yield Fact**
When working with stool samples that may contain Salmonella, it's essential to handle them carefully to avoid cross-contamination. Always use aseptic techniques when handling stool samples, and ensure that all equipment and surfaces are properly disinfected.
**Correct Answer: C. Selenite F broth**