What causes bacterial corneal ulcers?

Updated: Nov 08, 2018
  • Author: Jesse Borke, MD, FACEP, FAAEM; Chief Editor: Barry E Brenner, MD, PhD, FACEP  more...
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Answer

Bacterial corneal ulcers may follow a break in the corneal epithelium, thereby providing an entry for bacteria. The traumatic episode may be minor, such as a minute abrasion from a small foreign body, or may result from such causes as tear insufficiency, malnutrition, or contact lens use. Increased use of soft contact lenses in recent years has led to a dramatic rise in the occurrence of corneal ulcers, particularly due to Pseudomonas aeruginosa. [1]

Bacteria that can penetrate through intact corneal epithelium include Corynebacterium diphtheriae, Haemophilus influenzae, Neisseria gonorrhoea, Neisseria meningitidis, and Listeria species.

Common bacterial isolates cultured from patients with keratitis include P aeruginosa, coagulase-negative staphylococci, S aureus, S pneumoniae, and Enterobacteriaceae (including Klebsiella, Enterobacter, Serratia, and Proteus). K pneumoniae mucoid phenotype and its ability to form biofilm may be important in producing a corneal ulceration. Agents such as N-acetylcysteine may have a role in treatment because they inhibit biofilm formation.


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