Linezolid, used in extensively drug-resistant TB (XDR-TB) regimens, exerts its antibacterial action by which mechanism?
- A Inhibition of DNA gyrase
- B Inhibition of protein synthesis at the 50S ribosomal subunit ✓
- C Inhibition of cell wall synthesis by binding D-Ala-D-Ala
- D Inhibition of mycolic acid synthesis
Correct answer: B. Inhibition of protein synthesis at the 50S ribosomal subunit
Explanation
Linezolid is an oxazolidinone that inhibits protein synthesis by binding to the 23S rRNA of the 50S ribosomal subunit, preventing formation of the initiation complex. It is bacteriostatic against M. tuberculosis. Its use in XDR-TB is limited by myelosuppression (thrombocytopenia) and peripheral neuropathy with prolonged therapy beyond 4-6 weeks.
Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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