Sputum positive TB patients on chemotherapy should be isolated at least for
**Core Concept**
Isolation of sputum-positive tuberculosis (TB) patients is crucial to prevent the spread of Mycobacterium tuberculosis to others. This is based on the principle of airborne transmission, where droplets containing M. tuberculosis can be inhaled by others.
**Why the Correct Answer is Right**
The duration of isolation is determined by the effectiveness of chemotherapy in rendering the patient non-infectious. Sputum positivity indicates that the patient is still shedding M. tuberculosis in their sputum, posing a risk to others. Chemotherapy is most effective when the patient is on a combination of first-line anti-TB drugs, such as isoniazid, rifampicin, pyrazinamide, and ethambutol. The patient is usually declared non-infectious when they have been on effective treatment for at least 2 weeks and have two consecutive negative sputum smears.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the duration of isolation is not solely determined by the type of TB medication used, but rather by the patient's sputum status and the effectiveness of treatment.
* **Option B:** This option is incorrect because the World Health Organization recommends a minimum of 2 weeks of effective treatment before declaring a patient non-infectious.
* **Option C:** This option is incorrect because the duration of isolation is not solely determined by the patient's symptoms, but rather by their sputum status and the effectiveness of treatment.
**Clinical Pearl / High-Yield Fact**
TB patients should be isolated until they have two consecutive negative sputum smears on two separate occasions, at least 8 hours apart. This is because the risk of transmission is highest when the patient is shedding M. tuberculosis in their sputum.
**Correct Answer: C. 8 weeks.**