| Line 1: |
Line 1: |
| − | <big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
| + | #REDIRECT[[:Category:Listeria species]] |
| − | <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
| |