Vancomycin is active against which type of bacteria?

Vancomycin is active against which type of bacteria?

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

Answer: (A)

Vancomycin works by binding the D-Ala-D-Ala terminus of peptidoglycan precursors, blocking cell-wall synthesis. That target is accessible mainly in Gram-positive organisms, which have exposed peptidoglycan and no outer membrane barrier. Because Gram-negatives have an outer membrane that prevents vancomycin from reaching its target, the drug is ineffective against them. MRSA, being a Gram-positive pathogen, is susceptible, whereas Gram-negatives are not. While vancomycin is described as targeting Gram-positive bacteria, its use against certain Gram-positive anaerobes exists in specific contexts (for example, oral vancomycin for C. difficile in the gut), but systemic activity remains focused on Gram-positive organisms rather than a broad spectrum.

Vancomycin works by binding the D-Ala-D-Ala terminus of peptidoglycan precursors, blocking cell-wall synthesis. That target is accessible mainly in Gram-positive organisms, which have exposed peptidoglycan and no outer membrane barrier. Because Gram-negatives have an outer membrane that prevents vancomycin from reaching its target, the drug is ineffective against them. MRSA, being a Gram-positive pathogen, is susceptible, whereas Gram-negatives are not. While vancomycin is described as targeting Gram-positive bacteria, its use against certain Gram-positive anaerobes exists in specific contexts (for example, oral vancomycin for C. difficile in the gut), but systemic activity remains focused on Gram-positive organisms rather than a broad spectrum.