Difference between revisions of "Listeria species"
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(New page: <big><center>'''BACK TO INFECTIOUS AGENTS AND PARASITES'''</center></big> <big><center>'''BACK TO BACTERIA'''</center></big>) |
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<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big> | <big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big> | ||
<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big> | <big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big> | ||
| + | |||
| + | ===Overview=== | ||
| + | |||
| + | *6 species | ||
| + | *Saprophytes in soil | ||
| + | *''L. monocytogenes'' and ''L. ivanovii'' are pathogens | ||
| + | *Carried by sheep and goats and shed in faeces and milk especially during stress | ||
| + | *Can cause septicaemia, encephalitis and abortion | ||
| + | |||
| + | |||
| + | ===Characteristics=== | ||
| + | |||
| + | *Small Gram negative rods | ||
| + | *Catalase positive, oxidase negative | ||
| + | *Motile | ||
| + | *Facultative anaerobes | ||
| + | *''L. monocytogenes is haemolytic on blood agar due to a cytolytic protein, listeriolysin; grows at range of pH values and temperatures | ||
| + | *''L. ivanovii produces strong haemolytic zone | ||
| + | *Small, smooth, transparent colonies after 24 hours incubation | ||
| + | |||
| + | |||
| + | ===Pathogenesis and pathogenicity=== | ||
| + | |||
| + | *Infection by ingestion of contaminated feed | ||
| + | *Bacteria penetrate M cells in intestinal Peyer's patches | ||
| + | *Spread to tissues via blood and lymph | ||
| + | *Transplacental transmission in pregnant animals | ||
| + | *Bacteria may gain entry via breaks in oral or nasal mucosa, migrate in cranial nerves to cause neural signs | ||
Revision as of 07:01, 20 July 2008
Overview
- 6 species
- Saprophytes in soil
- L. monocytogenes and L. ivanovii are pathogens
- Carried by sheep and goats and shed in faeces and milk especially during stress
- Can cause septicaemia, encephalitis and abortion
Characteristics
- Small Gram negative rods
- Catalase positive, oxidase negative
- Motile
- Facultative anaerobes
- L. monocytogenes is haemolytic on blood agar due to a cytolytic protein, listeriolysin; grows at range of pH values and temperatures
- L. ivanovii produces strong haemolytic zone
- Small, smooth, transparent colonies after 24 hours incubation
Pathogenesis and pathogenicity
- Infection by ingestion of contaminated feed
- Bacteria penetrate M cells in intestinal Peyer's patches
- Spread to tissues via blood and lymph
- Transplacental transmission in pregnant animals
- Bacteria may gain entry via breaks in oral or nasal mucosa, migrate in cranial nerves to cause neural signs