Recommended transpo medium for stool specimen suspected to contain enteric pathogen is
**Question:** Recommended transpo medium for stool specimen suspected to contain enteric pathogen is
A. MacConkey agar
B. Blood agar
C. Cholesterol agar
D. Eosin Methylene Blue (EMB) agar
**Core Concept:**
Enteric pathogens are a group of bacteria and viruses that cause gastrointestinal infections, such as diarrhea, dysentery, and food poisoning. To isolate and identify these pathogens, appropriate culture media are required. The process of transporting the stool specimen to the laboratory is called transpo medium.
**Why the Correct Answer is Right:**
D. Eosin Methylene Blue (EMB) agar is the correct transpo medium for stool specimens suspected to contain enteric pathogens because it is a selective and differential medium. It is selective for gram-negative bacteria and provides differential characteristics for identification of certain bacteria like Salmonella, Shigella, and Yersinia. EMB agar contains eosin and methylene blue as the primary differential agents, which stain bacteria differently based on their cell wall composition. Eosin stains gram-negative bacteria pink, while methylene blue stains gram-positive bacteria blue.
**Why Each Wrong Option is Incorrect:**
A. MacConkey agar is used for the detection of lactose fermenters (bacteria that ferment lactose) in stool specimens. It does not provide specific identification of enteric pathogens.
B. Blood agar is used for general isolation of aerobic bacteria but is not a selective medium for enteric pathogens.
C. Cholesterol agar is used for the isolation and identification of Clostridium difficile, a cause of antibiotic-associated diarrhea. It is not a general medium for detecting enteric pathogens.
**Clinical Pearl:**
Transporting stool specimens using Eosin Methylene Blue agar ensures that the enteric pathogens are selectively isolated and identified, facilitating prompt diagnosis and appropriate treatment. This helps in preventing complications associated with untreated or misdiagnosed enteric infections, including malnutrition, electrolyte imbalances, and secondary infections.