Keratitis

Background

• Inflammation of the cornea

Etiology

• Bacteria
  • Gram-positive cocci
    • Staphylococcus aureus
    • Staphylococcus epidermidis
    • Streptococcus pneumoniae, Streptococcus pyogenes, viridans group streptococci
    • Enterococcus faecalis
    • Peptostreptococcus species
  • Gram-positive bacilli
    • Bacillus coagulans, Bacillus cereus, Bacillus lichenformis
    • Brevibacillus brevis, Brevibacillus iaterosporus
    • Corynebacterium diphtheriae
    • Clostridium perfringens, Clostridium tetani
  • Gram-negative coccobacilli
    • Neisseria gonorrhoeae
    • Moraxella lacunata, Moraxella nonliquefaciens, Moraxella catarrhalis
    • Acinetobacter calcoaceticus
    • Pasteurella multocida
  • Gram-negative bacilli
    • Pseudomonas aeruginosa, Pseudomonas stutzeri, Pseudomonas fluorescens
    • Burkholderia mallei
    • Proteus mirabilis
    • Serratia marcescens
    • Escherichia coli
    • Klebsiella pneumoniae
    • Morganella morganii
    • Aeromonas hydrophila
    • Bartonella henselae
  • Other bacteria
    • Chlamydia trachomatis
    • Treponema pallidum, mostly in congenital syphilis and presents in adolescence
    • Borrelia burgdorferi
    • Nocardia species, associated with surgery
• Mycobacteria
  • Mycobacterium tuberculosis
  • Mycobacterium chelonae, th most common NTM, which are associated with surgery
  • Mycobacterium gordonae
  • Mycobacterium mycogenicum
• Viruses
  • Herpes simplex virus, the most common viral cause
  • Varicella-zoster virus, which can occur before, during, or after a zoster eruption
  • Adenovirus
  • Vaccinia virus
  • Epstein-Barr virus
  • Measles virus
  • Enterovirus
  • Coxsackievirus
• Fungi
  • Fusarium species, the most common fungal cause
  • Candida species
  • Aspergillus species
  • Acremonium species
  • Alternaria species
  • Penicillium species
  • Bipolaris species
  • Nosema species
  • Vitaforma corneae
  • Encephalitozoon species
• Parasites
  • Acanthamoeba polyphaga, Acanthamoeba castellanii, associated with contact lenses
  • Onchocerca volvulus
  • Leishmania brasiliensis
  • Trypanosoma species
• Non-infectious causes

Clinical Manifestations

• Red, painful eye with foreign body sensation
• Decreased visual acuity
• Tearing ± purulent discharge (depending on etiology)
• Corneal edema
• Fluorescein dye may help visualize corneal ulcerations