A 38-year-old farmer presents with a 3-day history of severe ocular pain, photophobia, and purulent discharge from the right eye. Slit-lamp examination reveals a central corneal ulcer with stromal infiltration and hypopyon. Gram stain of corneal scrapings shows gram-positive cocci in clusters. What is the drug of choice for empirical topical therapy?

Question

Accepted Answer

B. Fortified cefazolin 5% + fortified gentamicin 1.4%. ## Bacterial Corneal Ulcer — Empirical Topical Therapy

**Key Point:** Fortified topical antibiotics (cefazolin + gentamicin) are the gold standard for empirical treatment of bacterial corneal ulcers with stromal involvement and hypopyon, pending culture and sensitivity results.

### Rationale for Fortified Cefazolin + Gentamicin

1. **Broad-spectrum coverage**: Cefazolin (3rd-generation cephalosporin) covers gram-positive cocci (including *Staphylococcus aureus*, *Streptococcus pneumoniae*) and some gram-negatives; gentamicin covers gram-negative rods (*Pseudomonas aeruginosa*, *Enterobacteriaceae*).
2. **High corneal penetration**: Fortified formulations (5% cefazolin, 1.4% gentamicin) achieve therapeutic corneal levels without systemic absorption.
3. **Synergistic effect**: The combination provides superior bactericidal activity for severe, sight-threatening infections.
4. **Hypopyon presence**: Indicates anterior chamber involvement and significant bacterial load — requires aggressive dual therapy.

### Dosing Protocol
- **Frequency**: Every 1 hour while awake (initially), then taper as clinical improvement occurs.
- **Duration**: 7–14 days depending on ulcer healing and culture results.

**High-Yield:** Fortified antibiotics are **not** used for prophylaxis or mild conjunctivitis — reserve for **stromal ulcers with hypopyon or significant infiltration**.

### Comparison of Topical Agents in Bacterial Corneal Ulcer

| Agent | Spectrum | Penetration | Indication | Limitation |
|-------|----------|-------------|-----------|------------|
| Fortified cefazolin + gentamicin | Gram-positive + gram-negative | Excellent (fortified) | Empirical severe bacterial ulcer | Requires compounding; frequent dosing |
| Fluoroquinolone (moxifloxacin) | Broad-spectrum | Good | Mild–moderate, contact lens ulcers | Monotherapy inadequate for severe stromal disease |
| Natamycin 5% | Fungal (Candida, Aspergillus) | Moderate | Fungal ulcer | No antibacterial activity |
| Acyclovir 3% | Herpes simplex virus | Poor corneal penetration | HSV keratitis | No bacterial coverage |

**Clinical Pearl:** In resource-limited settings where fortified antibiotics are unavailable, a fluoroquinolone (moxifloxacin or ofloxacin) may be used as a second-line option, but efficacy is lower for severe infections.

**Warning:** Do not use fluoroquinolone monotherapy for hypopyon ulcers — risk of treatment failure and corneal perforation.

Answer

A. Acyclovir 3%

Answer

C. Fluoroquinolone monotherapy (moxifloxacin 0.5%)

Answer

D. Natamycin 5%

Explanation

Bacterial Corneal Ulcer — Empirical Topical Therapy

Rationale for Fortified Cefazolin + Gentamicin

Dosing Protocol

Comparison of Topical Agents in Bacterial Corneal Ulcer

Practice similar questions

Join our NEET PG community

Agent	Spectrum	Penetration	Indication	Limitation
Fortified cefazolin + gentamicin	Gram-positive + gram-negative	Excellent (fortified)	Empirical severe bacterial ulcer	Requires compounding; frequent dosing
Fluoroquinolone (moxifloxacin)	Broad-spectrum	Good	Mild–moderate, contact lens ulcers	Monotherapy inadequate for severe stromal disease
Natamycin 5%	Fungal (Candida, Aspergillus)	Moderate	Fungal ulcer	No antibacterial activity
Acyclovir 3%	Herpes simplex virus	Poor corneal penetration	HSV keratitis	No bacterial coverage