In bacterial keratitis, which fortified antibiotic regimen is added when the infection is high risk or involves the visual axis?

• A. Fortified Tobramycin 1.4% q1h and Fortified Cefazolin 5% q1h
• B. Moxifloxacin 0.5% and Polymyxin B - Trimethoprim q2h
• C. Cyclopentolate 1% tid for pain
• D. Prednisolone acetate 1% qid after healing

Answer: (A)

When bacterial keratitis is high risk or involves the visual axis, the aim is to deliver very high local antibiotic concentrations quickly to control the infection and minimize scarring that could impair vision. Fortified antibiotics are prepared at high concentrations and given frequently to achieve treatment levels that penetrate an active ulcer and surrounding inflamed tissue.

The combination of fortified tobramycin 1.4% and fortified cefazolin 5% provides broad, immediate coverage: tobramycin targets Gram-negative bacteria, including Pseudomonas, while cefazolin covers Gram-positive cocci such as Staphylococcus and Streptococcus. Using them together at hourly dosing around the clock achieves rapid, intensive treatment crucial for eyes at risk of vision loss, especially when the visual axis is involved.

Other options either do not provide the same level of potency and rapid coverage (non-fortified regimens) or are not antimicrobial therapies appropriate for an active infection (cycloplegics or steroids), so they are not suitable as the initial high-risk management.