A patient with pre-XDR pulmonary tuberculosis is started on an all-oral shorter MDR-TB regimen that includes a diarylquinoline. Which molecular target does this drug inhibit?

• A DNA-dependent RNA polymerase beta subunit
• B Arabinosyltransferase involved in arabinogalactan synthesis
• C DNA gyrase subunit A
• D Proton pump of mycobacterial F-type ATP synthase ✓

Explanation

Bedaquiline, the first diarylquinoline approved for multidrug-resistant tuberculosis, selectively inhibits the proton pump of mycobacterial F-type ATP synthase, collapsing ATP production. Its target has no human homolog, giving selective toxicity, though QT prolongation remains the major adverse effect requiring ECG monitoring. RNA polymerase is the target of rifampicin, DNA gyrase of fluoroquinolones, and arabinosyltransferase of ethambutol, which makes those options mechanistically distinct and easily eliminated.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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