**Question:** TB multidrug regimen is given to-

A. 4 drugs including Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol
B. 3 drugs including Isoniazid, Ethambutol, and Rifampicin
C. 4 drugs including Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol
D. 2 drugs including Isoniazid and Rifampicin

**Core Concept:**

Tuberculosis (TB) is a bacterial infection primarily caused by Mycobacterium tuberculosis, which primarily affects the lungs but can also affect other organs. Treatment for TB involves a combination of antibiotics to ensure the effective elimination of the pathogen and prevent the development of drug-resistant strains. The World Health Organization (WHO) recommends a short-course, directly observed treatment strategy (DOTS) for treating TB, which includes a combination of drugs to ensure optimal treatment outcomes.

**Why the Correct Answer is Right:**

The correct answer (C) is based on the standard World Health Organization (WHO) recommended drug regimen for treating TB. The regimen includes four drugs: Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol. This combination is effective in ensuring the rapid sterilization of the bacilli and preventing the development of drug-resistant strains.

**Why Each Wrong Option is Incorrect:**

A. Including Ethambutol in the regimen is incorrect as it is only used in the initial phase of treatment, typically for 2 months, to prevent the development of resistance to Isoniazid and Rifampicin.

B. Including Ethambutol in the regimen is incorrect as it is only used in the initial phase of treatment, typically for 2 months, to prevent the development of resistance to Isoniazid and Rifampicin.

D. Including two drugs is incorrect, as TB requires a combination of drugs to target multiple essential cellular processes and ensure the complete elimination of the M. tuberculosis pathogen.

**Clinical Pearl:**

Isoniazid and Rifampicin are considered the cornerstone drugs in TB treatment due to their ability to target the mycobacterial cell wall synthesis and DNA synthesis. Pyrazinamide and Ethambutol contribute to the treatment regimen by targeting different aspects of the pathogen's survival and growth, thus improving treatment outcomes and reducing the development of drug resistance.

**Explanation:**

The correct answer (C) is selected because it includes all essential drugs in the WHO-recommended regimen for treating TB. The regimen targets multiple cellular processes of Mycobacterium tuberculosis, ensuring the effectiveness of the treatment and preventing the development of drug-resistant strains. By including all four drugs (Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol), the regimen effectively kills the bacteria and prevents the development of drug-resistant strains.