Moraxella

• Moraxella

  • Gram-negative, short, plump rods or coccobacilli, usually occur in pairs
  • Strict aerobes, non-motile
  • Hemolytic
  • Do not attack carbohydrates, derive their energy by oxidation of amino acids
  • Oxidase positive, Catalase positive
  • Optimal growth on enriched media (blood or serum)
  • Optimal temperature for growth is 33-35°C
• Direct Microscopy

  Fluorescent Antibody Technique (FAT)
• Sheep-blood agar


  35°C for 48-72 hours
• MacConkey agar


  M. bovis is unable to grow
• Moraxella bovis


  Infectious Bovine Keratoconjunctivitis (IBK) (Pink eye or New Forest Disease)
• Predisposing factors for Moraxella bovis

  • Age
  • Breed
  • Fly activity
  • Ocular irritants
  • Concurrent infections
  • Vitamin deficiency
• Transmission of Moraxella bovis

  1. Direct contact with infected animals

  2. By aerosols

  3. Through flies acting as vectors
• Treatment and Prevention of Moraxella bovis

  1. Antibiotic therapy (subconjunctivally or topically)

  2. Farm management (isolation of affected animals, reduction of exposure to mechanical irritants, use of insecticidal ear tags)

  3. Vitamin A supplementation
• Stage 1 Clinical Signs of (IBK) (Pink eye or New Forest Disease)

  -       Lacrimation

  -       Increased sensitivity to light

  -       Frequent blinking of the eyes

  -       Redness along the eyelids

  -       Small ulcer in the center of the cornea "small white spot"

  Cornea develops cloudy gray appearance
• Stage 2 Clinical Signs of (IBK) (Pink eye or New Forest Disease)

  -       Ulcer spreads across the cornea

  -       Cornea becomes increasingly cloudy

  -       Dark color of the iris
• Stage 3 Clinical Signs of (IBK) (Pink eye or New Forest Disease)

  -       Ulcer covers most of the cornea

  -       Eyes are filled with fibrins that gives yellow appearance
• Stage 4 Clinical Signs of (IBK) (Pink eye or New Forest Disease)

  -       Ulcer extends completely through the cornea

  -       Iris may protrude through the ulcer

  -       Glaucoma

  -       Eye will be permanently blind
• Sources/Reservoir

  -       Commensals on the mucous membrane of carrier cattle (Conjunctiva or nasopharynx)

  -       Susceptible to desiccation and do not survive well away from the animal host

  -       Can survive for up to 72 hours in the salivary organs and on the body surface of flies, which can act as vectors
• Virulence Factor

  (LPS) - Potent endotoxin

  Fimbriae and Pili - Mediates attachment of the organisms to the cornea

  Hemolysin - Damages the cell membranes of the neutrophils

  Lytic enzymes (Fibrinolysin, Phosphatase, Hyaluronidase, Aminopeptidase) - Contributes to breakdown of its collagen matrix

  Dermonecrotic toxin - Produces the corneal lesions typical of pinkeye
• Infectious Bovine Keratoconjuctivitis

  Bos taurus is more susceptible that Bos indicus