Which statement correctly describes the initial three-drug regimen used for active TB in the material?

Which statement correctly describes the initial three-drug regimen used for active TB in the material?

• A. Isoniazid only
• B. Rifampin only
• C. Isoniazid, Rifampin, and Pyrazinamide
• D. Isoniazid, Rifampin, Pyrazinamide, and Ethambutol

Answer: (C)

The key idea is that initial active TB treatment uses a combination of drugs with different actions to quickly reduce the bacillary load and prevent drug resistance. Isoniazid, rifampin, and pyrazinamide together form a powerful trio: isoniazid rapidly kills actively growing bacteria, rifampin blocks RNA synthesis and has strong sterilizing activity to prevent relapse, and pyrazinamide works well against semi-dormant bacilli in the acidic environments found in TB lesions, helping shorten the course of therapy. Ethambutol is often included when susceptibility to the main drugs is not yet known to guard against selecting resistant strains; if susceptibility is established, ethambutol can be omitted, leaving the three-drug regimen.

The key idea is that initial active TB treatment uses a combination of drugs with different actions to quickly reduce the bacillary load and prevent drug resistance. Isoniazid, rifampin, and pyrazinamide together form a powerful trio: isoniazid rapidly kills actively growing bacteria, rifampin blocks RNA synthesis and has strong sterilizing activity to prevent relapse, and pyrazinamide works well against semi-dormant bacilli in the acidic environments found in TB lesions, helping shorten the course of therapy. Ethambutol is often included when susceptibility to the main drugs is not yet known to guard against selecting resistant strains; if susceptibility is established, ethambutol can be omitted, leaving the three-drug regimen.