Principles of antibiotic use in the treatment of bacterial keratitis, drug selection, route of administration, initial response, and follow-up criteria

Treatment of bacterial keratitis hinges on prompt and targeted antibiotic therapy. Empirical broad-spectrum antibiotics are used initially, then tailored based on gram staining and culture results. Delivery methods vary based on severity and location of infection.

🔹 Strategy Overview

1. Empirical Therapy
    - For unknown or polymicrobial cases
    - 1st-gen cephalosporin + aminoglycoside or 4th-gen fluoroquinolone monotherapy
2. Targeted Therapy
    - Based on smear/culture
    - MRSA: Fortified Vancomycin
    - Pseudomonas: Fortified Tobramycin
    - Neisseria: Ceftriaxone
    - Corynebacterium: Cefazolin
3. Delivery Routes
    - Topical drops: most effective, frequent dosing required (q5–15min initially)
    - Ointment: adjunct at night
    - Subconjunctival injection: if risk of perforation or poor compliance
    - Systemic antibiotics: for Neisseria, neonates, scleral or intraocular spread
4. Monitoring
    - Evaluate clinical response within 2–3 days: reduced infiltrate, epithelial healing, inflammation subsiding

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📋 Antibiotic Therapy Summary Table (English)

Type of TreatmentMain OptionsUse Case / Notes

Broad-spectrum (initial)	Cefazolin + Tobramycin Moxifloxacin alone	When culture is pending or unclear
Gram-positive bacteria	Cefazolin, Vancomycin	Vancomycin for MRSA, cefazolin for general G(+)
Gram-negative bacteria	Tobramycin, Gentamicin, Ceftriaxone	For Pseudomonas, Haemophilus, Neisseria
Topical drops	Hourly dosing initially, taper over time	Preferred route, high ocular surface penetration
Subconjunctival injection	1 mL max per site, different sites if dual drugs	When perforation is imminent or poor compliance
Systemic antibiotics	Ceftriaxone, Vancomycin	For neonatal, Neisseria, or intraocular risks
Clinical improvement	↓ Infiltrate, defined borders, healing epithelium	Reassess in 48–72 hours