Culture medium for cultivation of mycobacterium is: September 2005 & 2011
**Core Concept**
Mycobacteria are a group of acid-fast bacteria that require a specific culture medium to grow, which is different from other types of bacteria. The culture medium for mycobacteria must be able to withstand the high pH and nutrient requirements of these organisms.
**Why the Correct Answer is Right**
Mycobacteria are typically grown on solid media, such as Löwenstein-Jensen (LJ) agar or Middlebrook 7H10 agar. These media contain ingredients like glycerol, asparagine, and malachite green that help to inhibit the growth of other bacteria and fungi while allowing mycobacteria to grow. The LJ medium also contains a high concentration of sodium chloride, which helps to select for mycobacteria that are able to tolerate high salt concentrations. The malachite green in the medium acts as an antibacterial agent, preventing the growth of other bacteria that might compete with mycobacteria for nutrients.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify a medium that is specifically designed for the cultivation of mycobacteria. While other media might support the growth of some types of bacteria, they are not optimized for mycobacteria.
* **Option B:** This option is incorrect because it is not a commonly used medium for the cultivation of mycobacteria. While some types of bacteria might be grown on this medium, it is not the best choice for mycobacteria.
* **Option C:** This option is incorrect because it does not contain the specific ingredients that are necessary for the growth of mycobacteria. While some types of bacteria might be grown on this medium, it is not optimized for mycobacteria.
**Clinical Pearl / High-Yield Fact**
It's worth noting that mycobacteria require a longer incubation period than many other types of bacteria, typically 4-6 weeks. This is because mycobacteria grow slowly and require a longer time to become visible on the culture medium.
**Correct Answer:** C. Löwenstein-Jensen (LJ) agar