Tigecycline retains activity against organisms carrying tet(A) efflux pumps and tet(M) ribosomal protection determinants that confer classical tetracycline resistance. The structural feature responsible for this is:

• A Addition of a bulky N,N-dimethylamino group at position 7 preventing pump recognition
• B Glycosylation at the C5 position which blocks binding of protective proteins
• C Replacement of the central four-ring nucleus with a tricyclic scaffold
• D A 9-tert-butylglycylamido side chain that sterically hinders both efflux and ribosomal protection proteins ✓

Explanation

Tigecycline is a 9-tert-butylglycylamido derivative of minocycline, the first glycylcycline. This substitution at the B ring creates steric hindrance that prevents recognition by Tet(A) class efflux pumps and distorts binding of Tet(M) type ribosomal protection proteins. The core four-ring structure is retained, ruling out option C, and the modification is on carbon 9, not position 7 or C5.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.