Listeria Flashcards
What is listeria
Genus of rod-shaped gram negatives. Causes listeriosis.
Listeriosis symptoms:
Mostly elderly, immucompromised or pregnant women. Most often through food poisoning. Can cause fever and diaerrhea in normal people. In compromised it causes intrauterine infections, meningitis and septicemia. 1-90 days of incubation period.
Almost exclusively listeria monocytogenes.
Most common listeria
1) Listeria monocytogenes
How do we get listeria?
From food - very prevalent bacteria in environment and can colonise sites very food is produced. Can grow at fridge temperature.
Listeria pathogenesis:
1) Enters cells trhough lisertial surface proteins (both phagocytes and non-phagocytes) into membrane bound vacuole
2) listeriolysin O lysis vacuole - bacteria now in cytoplasma.
3) host cell actin polymerises on head of listeria propelling it forward. Reaches cell membrane and same thing happens again.
Listeria in pregnancy
Maternal listeriosiscan spreadd to the child, which can be measured in the amniotic fluid. AFter birth child willhave fever and it can sometimes be very severe.
Adult infection:
Mainly bacteriemia with following CNS infection. Mostly immunocompromised. Can also cause menigitis which is hard to tell from meningochoccus etc. Also gastroenteritis and bacterimia (mostly elderly)
Who gets listeria
Prevalance increases with age.
Food attributes contributing to listeria:
1) high water and neutral pH
2) Heavy initial bacterial contamination.
3) long shelf life
4) Ready to eat (no cooking)
Conjunctivitis
Laboratory acquired infections
Listeria detection:
Usually blood or CSF cultures. Also PCR.
Treatment of listeria:
Antibiotics have been foundvery useful: Ampicilin, pnicilin and cephalosporin.
