Vancomycin is effective against which multidrug-resistant organism?

Vancomycin is effective against which multidrug-resistant organism?

• A. E. coli
• B. MRSA
• C. Pseudomonas aeruginosa
• D. Enterococcus faecalis

Answer: (B)

Vancomycin works by binding to the D-Ala-D-Ala terminus of peptidoglycan precursors, blocking cell wall synthesis, which makes it highly active against Gram-positive bacteria. Among the options, MRSA is a Gram-positive multidrug-resistant organism for which vancomycin is a primary therapy. The drug’s ability to access and disrupt the thick cell wall of Gram-positive organisms explains its effectiveness here. E. coli and Pseudomonas aeruginosa are Gram-negative and have an outer membrane that impedes vancomycin’s access, so the drug is not effective against them. Enterococcus faecalis can be susceptible to vancomycin, but many strains are vancomycin-resistant, so it’s not reliably effective as an MDRO target in the same way MRSA is.

Vancomycin works by binding to the D-Ala-D-Ala terminus of peptidoglycan precursors, blocking cell wall synthesis, which makes it highly active against Gram-positive bacteria. Among the options, MRSA is a Gram-positive multidrug-resistant organism for which vancomycin is a primary therapy. The drug’s ability to access and disrupt the thick cell wall of Gram-positive organisms explains its effectiveness here.

E. coli and Pseudomonas aeruginosa are Gram-negative and have an outer membrane that impedes vancomycin’s access, so the drug is not effective against them. Enterococcus faecalis can be susceptible to vancomycin, but many strains are vancomycin-resistant, so it’s not reliably effective as an MDRO target in the same way MRSA is.