Which of the following is used for culturing M.Tuberculosis?
**Core Concept**
The question is testing the ability to identify the appropriate medium for culturing Mycobacterium tuberculosis (M. tuberculosis), a pathogenic bacterium responsible for causing tuberculosis (TB). M. tuberculosis requires a specific growth medium that can support its unique growth requirements.
**Why the Correct Answer is Right**
M. tuberculosis is typically cultured on a solid medium called Löwenstein-Jensen (LJ) agar. This medium is enriched with ingredients such as asparagine, glycerol, and iron salts that provide the necessary nutrients for the growth of M. tuberculosis. The LJ medium is selective, allowing the growth of M. tuberculosis while inhibiting the growth of other bacteria. The slow growth rate of M. tuberculosis on LJ agar is a characteristic feature that distinguishes it from other bacteria.
**Why Each Wrong Option is Incorrect**
* **Option A:** Blood agar is a type of enriched medium used for culturing various bacteria, but it is not suitable for M. tuberculosis due to its inability to provide the necessary nutrients and selective agents.
* **Option B:** MacConkey agar is a selective medium used for differentiating lactose-fermenting from non-lactose-fermenting Gram-negative bacteria, but it is not suitable for culturing M. tuberculosis.
* **Option C:** Sabouraud agar is a type of medium used for culturing fungi, and it is not suitable for culturing M. tuberculosis.
**Clinical Pearl / High-Yield Fact**
M. tuberculosis can be cultured on LJ agar within 4-6 weeks, but it may take up to 8 weeks for visible growth to occur. This slow growth rate emphasizes the importance of proper handling and containment of M. tuberculosis cultures to prevent laboratory-acquired infections.
**Correct Answer: C. Löwenstein-Jensen agar.**