What is the typical spectrum of activity for vancomycin?

What is the typical spectrum of activity for vancomycin?

• A. Gram-positive organisms only; active against MRSA but not Gram-negatives or anaerobes.
• B. Gram-negative organisms only; active against MRSA.
• C. Broad-spectrum including Gram-positives and Gram-negatives.
• D. Active only against anaerobes.

Answer: (A)

Vancomycin targets cell wall synthesis by binding the D-Ala-D-Ala terminus of peptidoglycan precursors. Because Gram-negative bacteria have an outer membrane that blocks access to this target, vancomycin is active mainly against Gram-positive organisms. It covers important Gram-positive pathogens such as MRSA and other streptococci and enterococci, but does not reliably affect Gram-negative bacteria, and its activity against anaerobes is not its defining feature (it’s not a broad or anaerobe-focused drug in standard use). Therefore, the typical spectrum is Gram-positive organisms only, including MRSA, with poor activity against Gram-negatives and limited, not primary, activity against anaerobes.

Vancomycin targets cell wall synthesis by binding the D-Ala-D-Ala terminus of peptidoglycan precursors. Because Gram-negative bacteria have an outer membrane that blocks access to this target, vancomycin is active mainly against Gram-positive organisms. It covers important Gram-positive pathogens such as MRSA and other streptococci and enterococci, but does not reliably affect Gram-negative bacteria, and its activity against anaerobes is not its defining feature (it’s not a broad or anaerobe-focused drug in standard use). Therefore, the typical spectrum is Gram-positive organisms only, including MRSA, with poor activity against Gram-negatives and limited, not primary, activity against anaerobes.