Corneal ulcer caused by Clostridium, Bacillus, Azotobacter, Nocardia

👁 “Uncommon Bacterial Keratitis – Clues to Rare Organisms”

While most corneal ulcers are caused by common bacteria like Staphylococcus or Pseudomonas,
rare pathogens like Clostridium, Bacillus, Nocardia, and Azotobacter may cause highly specific forms of keratitis,
often requiring tailored management due to their distinctive clinical signatures.

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🦠 Summary Table of Rare Bacterial Keratitis

PathogenClinical Hallmarks

Clostridium
– Anaerobic, gas-producing
– Forms bubbles in stroma → "foamy keratitis"
– Often after trauma/soil exposure
Bacillus
– Extremely rapid progression
– Multiple foci → stromal melting → perforation
– Seen in trauma or improper lens use
Azotobacter
– Rare water/soil pathogen
– Limited reports, may mimic other gram-negatives
Nocardia
– Begins as punctate infiltrates, then satellite lesions
– Typically elevated, non-painful central ulcer
– Fungal keratitis mimic

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🌟 Pathogens with Satellite Lesions

• S. aureus
• S. viridans
• Nocardia
• Fungi (Filamentous molds)

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✅ Clinical Insight
– Bubble-like infiltration = think Clostridium
– Rapid perforation = suspect Bacillus
– Satellite lesions + dry trauma history = evaluate for Nocardia or fungus