Listeria Flashcards
1
Q
When was listeria discovered and by whom?
A
- Murray, Webb, and Swann
- 1924
- L. Monocytogenes was isolated as etiological agent of a septicemic disease in guinea pigs and rabbits
2
Q
Who reported the first case of listeria in humans
A
A. Nyfeldt (1929)
3
Q
Characteristics of listeria
A
- gram +ve
- motile
- non-spore forming
- facultative anaerobe
- rod shaped
- catalase +ve
- oxidase -ve
- L-ramnose +ve
- has beta hemolysin
4
Q
Main species of Listeria genus
A
L. Monocytogenes
L. Innocua
L. Ivanovii
5
Q
Main clinical symptoms (human)
A
- fever, muscle aches, nausea, vomiting, diarrhea
- severe form: stiff neck, meningitis, Loss of balance, convulsions, abortion, stillbirth
6
Q
Importance of spoiled silage in Listeria contamination
A
Listeria can survive in silage for 12 years
7
Q
Major pathogenic factors
A
- Listerolysin O: virulence fact. Responsible for beta hemolysis on RBCs & destruction of phagocytic cells; in all L. Monocytogenes strains
- Internalins: Membrane proteins promoting cellular uptake
- Listerolysin: mediated intracellular survival & phagosome escape
- Phospholipases: in lateral spread to adjacent cells
8
Q
Source and mode of transmission of L. Monocytogenes
A
- MOT: eating contaminated food, sexual contact, vertically
- Source: meat and milk of ruminants, pigs, chickens, fish, vegetables, etc.
9
Q
Role of listeria as food contaminant, incidence, and mortality rate
A
- low mortality & incidence rate
- recently found in ice cream, deli meat, cheese, enoki mushrooms
10
Q
Is listeria zoonotic?
A
Yes
11
Q
Invasive illness
A
Spread beyond gut
12
Q
Circling disease
A
- primarily ruminants
- encephalitic form of listeriosis
- can paralyze CN 4 and 7 (trigeminal & facial n.)
13
Q
Dx listeriosis
A
- isolate bacteria w/ oxford or Rapid L. Mono agar
- PCR
- L. Rhamnose +ve
14
Q
Tx
A
- animals: parenteral penicillin g or oxytetracycline (early)
- humans: penicillin, ampicillin, amoxicillin, fluid therapy & supportive care
- NO APPROVED VX
