Which TB drug is a core bactericidal agent used in standard therapy?

Which TB drug is a core bactericidal agent used in standard therapy?

• A. Ethambutol
• B. Rifampin
• C. Pyrazinamide
• D. Isoniazid (INH) is a core bactericidal agent

Answer: (D)

Isoniazid is highlighted because it provides rapid, potent killing of actively replicating Mycobacterium tuberculosis, making it a cornerstone of standard therapy. It works after activation by the bacterial enzyme KatG to inhibit mycolic acid synthesis, a vital component of the mycobacterial cell wall. This leads to quick reductions in bacterial load during the initial intensive phase of treatment when used with other drugs. While rifampin also has strong bactericidal activity, and pyrazinamide adds sterilizing effect, ethambutol is mainly bacteriostatic and serves to prevent resistance rather than provide strong bactericidal kill. The combination of isoniazid with other agents in the RIPE regimen underpins effective, multi-drug TB therapy.

Isoniazid is highlighted because it provides rapid, potent killing of actively replicating Mycobacterium tuberculosis, making it a cornerstone of standard therapy. It works after activation by the bacterial enzyme KatG to inhibit mycolic acid synthesis, a vital component of the mycobacterial cell wall. This leads to quick reductions in bacterial load during the initial intensive phase of treatment when used with other drugs. While rifampin also has strong bactericidal activity, and pyrazinamide adds sterilizing effect, ethambutol is mainly bacteriostatic and serves to prevent resistance rather than provide strong bactericidal kill. The combination of isoniazid with other agents in the RIPE regimen underpins effective, multi-drug TB therapy.