Listeria Flashcards
is Listeria a lactic acid bacteria?
yes
is Listeria high or low in GC content?
low
which species of Listeria is the most important as a pathogen of humans and animals?
L.monocytogenes
describe L.monocytogenes
how do you distinguish it from other bacteria?
- short
- G+ve
- non-spore forming
- catalase +ve
- facultative anaerobe
- TUMBLING motility at room temp but not at 37°C (to distinguish from others
what are the two types of disease that Listeria causes?
1) perinatal
- early onset: intrauterine inf, sepsis and death BEFORE birth
- late onset: infected at birth, meningitis and sepsis w/in 2-3 weeks. HIGH mortality
2) adult
- immunocompetent: flu like symptoms, gastro upset, clears in a few weeks
- immunocompromised: meningo-encephalitis and bacteriaemia
how is Listeriosis treated?
penicillin and gentamicin( gentamicin doesn’t enter host cells)
what is the reservoir of Listeria infection?
- infected animals
- silage
- infected humans
what is the normal route of infection for Listeria?
GI tract
which foods are associated with Listeria outbreaks?
how can it be prevented?
what difficulty comes with trying to prevent Listeria outbreaks?
dairy-soft unpasteurised cheese, packaged meat, fruits and veg
prevention: pasteurise dairy food, and cooking of food
BUT it is PSYCHOTROPHIC- grows in fridge temp
who is at high risk of Listeria infection?
pregnant women at 20x more likely
describe the pathogenesis of Listeria
- enters non phagocytic cells (like Fibroblasts) or passively enters phagocytic cells
- enters a memb bound PHAGOSOME inside cell
- leaves danger of phagosome to enter the cytosol using LISTERIOLYSIN
- induces cell ACTIN machinery to allow it to move through cell cytosol into NEW CELL
- forms DOUBLE MEMBRANE PHAGOSOME
- uses LISTERIOLYSIN and other phospholipases to break open double membrane phagosome
