**Question:** A 30-year-old female has sputum-positive TB. Her child is 3 years old. What is the recommended chemoprophylaxis?

**Core Concept:** Chemoprophylaxis in tuberculosis (TB) refers to the use of anti-TB medications to prevent the development of active TB disease in an individual who is at risk of acquiring the infection. In this case, the patient has sputum-positive TB, indicating active disease, and the child is a close contact. Chemoprophylaxis is recommended for close contacts of sputum-positive TB cases to reduce the risk of transmission and development of active disease.

**Why the Correct Answer is Right:** The recommended chemoprophylaxis for the child is isoniazid (INH), a first-line drug used to prevent active TB disease. INH works by inhibiting the growth of Mycobacterium tuberculosis, the bacterium causing TB. It is administered for a minimum of 6 months.

**Why Each Wrong Option is Incorrect:**

A. Ethionamide (ETH) is another first-line drug used in TB treatment but is not recommended for chemoprophylaxis due to its potential for causing liver toxicity and poor adherence.

B. Rifampicin (RIF) is a second-line drug used in TB treatment and is not recommended for chemoprophylaxis due to its higher risk of side effects and lower efficacy compared to INH.

C. Pyrazinamide (PZA) is a first-line drug used in TB treatment but is not recommended for chemoprophylaxis due to its high hepatotoxicity and shorter efficacy period (6 months).

D. Ethambutol (EMB) is a first-line drug used in TB treatment, but it is not recommended for chemoprophylaxis due to its potential for causing visual impairment and other side effects.

**Clinical Pearl:** Chemoprophylaxis with INH is crucial for close contacts of sputum-positive TB cases as it reduces the risk of transmission and development of active TB disease. The correct duration for chemoprophylaxis is 6 months.

Adverse effects and drug interactions should be monitored during treatment, and patient education regarding adherence and side effect management is essential to ensure successful chemoprophylaxis.