Maximum sterilising action is shown by which anti TB drug ?
**Core Concept**
The question tests the student's knowledge of anti-tubercular drugs, specifically their sterilizing action. **Sterilizing action** refers to the ability of a drug to kill dormant or non-replicating **Mycobacterium tuberculosis** bacteria.
**Why the Correct Answer is Right**
Although the correct answer choice is missing, the drug with maximum sterilizing action is typically considered to be **Rifampicin**. This is because Rifampicin has potent bactericidal activity against both replicating and non-replicating **M. tuberculosis**. It works by inhibiting **RNA synthesis** by binding to the **beta-subunit of RNA polymerase**.
**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific options provided, it's challenging to give a precise reason for each incorrect choice. However, generally, other anti-TB drugs like **Isoniazid** have strong bactericidal activity but are not considered to have the maximum sterilizing action compared to Rifampicin.
**Option B:** Similarly, this option would be incorrect if it were a drug like **Pyrazinamide**, which has sterilizing activity but is typically considered less potent than Rifampicin in this regard.
**Option D:** This option would be incorrect if it proposed a drug with primarily bacteriostatic action or less potent sterilizing effects.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that **Rifampicin** and **Pyrazinamide** are crucial for their sterilizing action in TB treatment, helping to shorten the treatment duration by killing non-replicating bacteria.
**Correct Answer:** Correct Answer: D. Rifampicin.