Tigecycline is a glycylcycline antibiotic that overcomes tetracycline resistance primarily because it:

• A Binds irreversibly to the 30S ribosomal subunit, preventing pump-mediated release
• B Is not a substrate for ribosomal protection proteins (RPPs) or tetracycline efflux pumps ✓
• C Inhibits DNA gyrase in addition to ribosomal binding
• D Is not hydrolysed by beta-lactamase enzymes that also degrade tetracyclines

Explanation

The 9-glycylamido substituent in tigecycline produces steric hindrance that prevents binding by ribosomal protection proteins (e.g., TetM, TetO) and makes it a poor substrate for most tetracycline-specific efflux pumps. It still binds the 30S subunit reversibly. Beta-lactamases do not affect tetracyclines; DNA gyrase is targeted by fluoroquinolones.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.