Streptococcus, Pneumococcus, S. viridans, Bacterial Keratitis (Corneal Ulcer) Characteristics, Pathological Forms, Differential Diagnosis

👁 “Streptococcal Keratitis – From Ulcer Serpens to Crystalline Keratopathy”

Streptococcus species, particularly S. pneumoniae and S. viridans,
are known to cause distinctive forms of bacterial keratitis, including
the classic serpiginous ulcers and the more indolent infectious crystalline keratopathy (ICK).

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🦠 Summary Table of Streptococcal Keratitis

OrganismClinical Features

S. pneumoniae
– Starts as focal purulent infiltrate
– Spreads serpiginously (like a snake = ulcer serpens)
– Ring-shaped ulcer may form
– Severe anterior chamber reaction: hypopyon, fibrin
– May lead to perforation
S. viridans
– Low virulence, often painless
– Forms non-painful ulcers, slow to progress
– Associated with ICK (infectious crystalline keratopathy)
– May show satellite lesions

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💡 Special Features

TermDescription

Ulcer serpens	Classic creeping edge ulcer from pneumococcus
Ring ulcer	Seen in: S. pneumoniae, Pseudomonas, Listeria, Acanthamoeba, fungi
ICK	Crystalline branching opacities within stroma, epithelium intact
Satellite lesions	Multiple small infiltrates near primary ulcer – common in fungi, S. viridans, Nocardia

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✅ Clinical Note
– Prompt diagnosis is crucial for S. pneumoniae keratitis due to its aggressive course
– S. viridans keratitis can mimic fungal ulcers or ICK – consider culture and steroid history

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