Unit 1- Listeria Flashcards
Listeria
Gram positive bacilli, facultative anaerobe, non-spore forming, catalase positive, intracellular, flagella, beta hemolytic, resistant to salt, grows in cold
Tumbling Motility
Umbrella shaped colony will grow in a semi solid motility media
Virulent Serotypes
1/2a in food, 1/2b, and 4b causes human epidemics
Muellen-Hinton Agar
Requires enrichment media, beta hemolytic on blood agar, produces acid fermentation, requires long incubation
Enrichment for Growth
FDA and ISO standard enrichment broth media that allow results within 48 hours
Resistant Conditions
High salt, inanimate objects, can multiply at fridge temperature
Habitat
Soil and decaying vegetation, frank pathogen
Most common host
Ruminants, sheep
Entry Route
Oral, associated with high iron silage in livestock
Exit Routes
Feces, abortion, milk
Body Structures
Flagella, internalin, invasion associated protein
Intracellular Immune Evasion
Hides from immune patrolling, destroys phagosome to prevent lysozyme binding and allow escape to neighboring cells
Enxymes
Superoxide dismutase and phospholipase
Superoxide Dismutase
Protects against free radicals from host phagocytes
Phospholipase
Pore-forming lysis on endocytosis membrane of the host to free from lysozome
Toxins
Beta hemolysin, listeriolysin, bacteriocins, actin polymerizing protein
Actin Polymerizing Protein
Directs actin filament formation to propel the bacteria from cell to cell
Body Systems
Cell membrane, intestinal barrier, placental barrier, blood-brain barrier
Pathogenesis
Attaches to epithelial cells or macrophages, intracellular invasion, intracellular multiplication, and spreads to other cells
Intracellular Invasion
Internalin binds surface protein on host and allows entrance to cell
Listeriosis
Shedding in feces to infect other hosts, translocation to lymph nodes, spleen and liver infection, bacteremia, placentitis and abortion, meningioencephalitis, and septicemia and shock
Neural Form
Microabscess in the brain, ataxia and circling disease, unilateral facial paralysis in silage fed sheep
Visceral Form
Septicemia causes gastroenteritis, liver and spleen damage, abortion, myocarditis, osteomyelitis, and mastitis
L. monocytogenes
Third leading cause of death from food in the US
Diagnosis
FDA or ISO enrichment broth or blood agar
Treatment
Beta lactimases
Control
Little known besides silage control and vaccine
