Which aminoglycoside/dexamethasone combination is used for gram negatives (Pseudomonas)?

• A. Tobramycin/Dexamethasone
• B. Gentamicin/Dexamethasone
• C. Amikacin/Dexamethasone
• D. Streptomycin/Dexamethasone

Answer: (A)

Tobramycin with dexamethasone is used for Pseudomonas (gram-negative) eye infections because tobramycin has strong anti-Pseudomonal activity, making it the preferred aminoglycoside for these organisms. The dexamethasone component adds anti-inflammatory benefit, helping to reduce corneal inflammation and potential scarring while the antibiotic fights the infection. While gentamicin also covers Pseudomonas, tobramycin is generally more potent against this organism in ocular practice, which is why this combined product is the common choice. Amikacin/dexamethasone exists but is less commonly chosen for typical Pseudomonas cases, and streptomycin is rarely used for ocular infections due to poorer penetration and higher toxicity.