Which antibiotic is a non-beta-lactam glycopeptide used as a last resort against MRSA and C. diff?

Which antibiotic is a non-beta-lactam glycopeptide used as a last resort against MRSA and C. diff?

• A. Vancomycin
• B. Isoniazid
• C. Aztreonam
• D. Rifampin

Answer: (A)

Vancomycin is a non-beta-lactam glycopeptide that blocks cell wall synthesis by binding to the D-Ala-D-Ala terminus of peptidoglycan precursors, preventing proper assembly of the bacterial cell wall. This mechanism makes it highly effective against Gram-positive bacteria, including MRSA, and it’s often reserved for use when beta-lactams fail or aren’t suitable. For Clostridioides difficile infections, vancomycin can be given orally to act directly in the gut, where the bacteria reside, since the drug isn’t absorbed well systemically. That combination of activity and the route of administration for C. diff is why vancomycin is considered a last-resort option. Other drugs listed belong to different classes or targets: isoniazid treats tuberculosis, aztreonam is a beta-lactam monobactam, and rifampin inhibits RNA synthesis, none of which fit the description of a non-beta-lactam glycopeptide used as a last resort for MRSA and C. diff.

Vancomycin is a non-beta-lactam glycopeptide that blocks cell wall synthesis by binding to the D-Ala-D-Ala terminus of peptidoglycan precursors, preventing proper assembly of the bacterial cell wall. This mechanism makes it highly effective against Gram-positive bacteria, including MRSA, and it’s often reserved for use when beta-lactams fail or aren’t suitable. For Clostridioides difficile infections, vancomycin can be given orally to act directly in the gut, where the bacteria reside, since the drug isn’t absorbed well systemically. That combination of activity and the route of administration for C. diff is why vancomycin is considered a last-resort option. Other drugs listed belong to different classes or targets: isoniazid treats tuberculosis, aztreonam is a beta-lactam monobactam, and rifampin inhibits RNA synthesis, none of which fit the description of a non-beta-lactam glycopeptide used as a last resort for MRSA and C. diff.