In severe ocular MRSA infections, which topical antibiotic is commonly reserved due to resistance concerns?

• A. Vancomycin
• B. Cefazolin
• C. Neomycin
• D. Gentamicin

Answer: (A)

When MRSA is involved in the eye, you need an antibiotic the organism is reliably susceptible to, because many common topical agents don’t work well. MRSA often shows resistance to beta-lactams such as cefazolin, and it can also resist or have limited effectiveness with aminoglycosides like gentamicin and neomycin. Vancomycin remains effective against MRSA, so it is reserved for severe ocular infections where MRSA is suspected or confirmed. In practice this means using fortified topical vancomycin to achieve high local concentrations, while the other drugs are avoided for routine severe MRSA coverage due to resistance concerns or limited activity.