What is the duration of the continuation phase after the initial 2-month intensive phase in drug-susceptible pulmonary TB?

• A. Six months.
• B. Four months.
• C. Two months.
• D. Eight weeks.

Answer: (B)

In drug-susceptible pulmonary TB, after the 2-month intensive phase, the continuation phase lasts four months. This continuation phase uses two drugs (isoniazid and rifampin) to finish eradicating any remaining bacilli and to minimize relapse, with the total recommended duration being six months. The intensive phase rapidly reduces the bacterial load, but the remaining organisms need additional time with a simpler drug combination to ensure full cure. Shorter continuation would risk relapse, while longer durations are not typically needed unless there are complicating factors.