Difference between revisions of "Moraxella bovis"
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*Virulent strains have fimbriae, are haemolytic and grow into agar | *Virulent strains have fimbriae, are haemolytic and grow into agar | ||
| + | *Fimbriae allow adherence to the cornea | ||
| + | *Q fimbriae are specific for colonisation; I fimbriae allow local persistence of infection | ||
| + | *Fimbrial antigens stimulate immunity | ||
| + | *Haemolysin, fibrinolysin, phosphatase, hyaluronidase and aminopeptidase as well as LPS contribute to virulence | ||
| + | *Haemolysin damages neutrophil membranes; release of hydrolytic enzymes from these neutrophils damages the corneal surface | ||
| + | *Isolates from carrier animals often avirulent, and are non-haemolytic and have no fimbriae; reversion to virulence can occur | ||
===Clnical infections=== | ===Clnical infections=== | ||
| − | + | *Infectious bovine keratoconjunctivitis, or pink-eye/New Forest disease is an ocular disease of cattle | |
*Highly contagious infection of superficial tissues of eye | *Highly contagious infection of superficial tissues of eye | ||
*Affects animals under 2 years old | *Affects animals under 2 years old | ||
| − | *Decreased weight gain in beef cattle, decreased milk production | + | *Decreased weight gain in beef cattle, decreased milk production in dairy herds |
| − | * | + | *Age-related immunity due to previous exposure |
| + | *Asymptomatic carrier animals harbour the bacteria in the nasolacrimal ducts, nasopharynx and vagina | ||
| + | *Transmission by direct contact, aerosol and via flies | ||
| + | *Clinical signs: blepharospasm, conjunctivitis, lacrimation | ||
| + | *Keratitis and corneal ulceration, opacity and abscessation may lead to panophthalmitis and permanent blindness | ||
| + | |||
| + | |||
Revision as of 17:28, 26 May 2008
Overview
- Moraxella bovis causes infectious bovine keratoconjunctivitis
- Found on mucous membranes of carrier cattle
- Susceptible to desiccation therefore short survival in environment
- Flies act as vectors, in which the bacteria can survive 72 hours
- Other species non-pathogenic
Characteristics
- Short, plump Gram negative rods or cocci occuring in pairs
- Non-motile
- Aerobic
- Catalase positive, oxidase postitive
- Unable to utilise sugars
- No growth on MacConkey agar
- Growth enhanced by addition of blood or serum to media
Pathogenesis and pathogenicity
- Virulent strains have fimbriae, are haemolytic and grow into agar
- Fimbriae allow adherence to the cornea
- Q fimbriae are specific for colonisation; I fimbriae allow local persistence of infection
- Fimbrial antigens stimulate immunity
- Haemolysin, fibrinolysin, phosphatase, hyaluronidase and aminopeptidase as well as LPS contribute to virulence
- Haemolysin damages neutrophil membranes; release of hydrolytic enzymes from these neutrophils damages the corneal surface
- Isolates from carrier animals often avirulent, and are non-haemolytic and have no fimbriae; reversion to virulence can occur
Clnical infections
- Infectious bovine keratoconjunctivitis, or pink-eye/New Forest disease is an ocular disease of cattle
- Highly contagious infection of superficial tissues of eye
- Affects animals under 2 years old
- Decreased weight gain in beef cattle, decreased milk production in dairy herds
- Age-related immunity due to previous exposure
- Asymptomatic carrier animals harbour the bacteria in the nasolacrimal ducts, nasopharynx and vagina
- Transmission by direct contact, aerosol and via flies
- Clinical signs: blepharospasm, conjunctivitis, lacrimation
- Keratitis and corneal ulceration, opacity and abscessation may lead to panophthalmitis and permanent blindness