Listeria

Question 1

Listeria gram stain

Answer 1

Gram positive coccobaccili (singly, often appears as diplo)

Question 2

Listeria spores?

Answer 2

Nonsporeforming

Question 3

Listeria oxygen requirements

Answer 3

Facultative anaerobe

Question 4

Listeria motility

Answer 4

Peritrichous flagella at RT (surrounding)

Polar flagella at host temperature

Question 5

Listeria hardiness

Answer 5

Can survive wide temperature range (1-45ºC) and salt concentrations (=<6.5%)

Question 6

Listeria found…

Answer 6

In mammal/bird intestinal track, ubiquitous soil/ plant,
— Soft cheeses, unwashed raw vegetables, raw or undercooked animal-based foods such as deli meat and hot dogs (Most damaging)

Question 7

4-Listeria virulence factors

Answer 7

1. Internalins
2. Phospholipase C
3. ActA
4. Listeriolysin O

Question 8

Listeria Internalins

Answer 8

Surface associated proteins that act to facilitate the uptake of the bacterium into the epithelial cells

Question 9

Listeria Phospholipase C

Answer 9

Facilitate spreading by enabling the organisms escape from the endoscope into the cytosol before can be digested by the lysosome

Question 10

Listeria ActA

Answer 10

Surface protein that facilitates the rearrangement of actin to propel the organism through the cell and into an adjacent cell (making the organism very invasive)

Question 11

Listeria pathogenesis

Answer 11

—Penetrates cell (most often gall bladder first) via internalin-mediated endocytosis
— release from phagosome through phospholipase C and listeriolysin O into the cytosol
— replication in cell
— invades adjacent cells through ActA-mediated host cell actin

Question 12

Listeriosis Disease (Early Onset)

Answer 12

Acquired in utero
—disseminated abscess and granuloma formation
—multiple organ failure
— may result in sillbirth, spontaneous miscarriage, or premature birth

Question 13

Listeriosis disease (Late Onset)

Answer 13

• occurs 2-3 weeks after birth
• meningitis with or without septicemia
• abscesses/ lesions may be found in liver, spleen, adrenals, respiratory tract, CNS and/or skin

Question 14

Listeriosis disease (adults)

Answer 14

In the healthy: usually mild condition from contaminated food resulting in flu-like symptoms and/or GI distress (24-hour flu)
Elderly/immunocompromised/ pregnant: may result in meningitis

Question 15

Listeria microscopy

Answer 15

Not much use- rarely seen in gram stain/ slow growing

Question 16

Listeria hemolysis/ motility

Answer 16

Weakly B-hemolytic with umbrella motility

Question 17

Listeria stereotyping

Answer 17

Done using O (cell associated) or H (flagella) antigen

Question 18

Listeria treatment

Answer 18

Penicillin is drug of choice
Animals should be vaccinated, and at-risk individuals should avoid cold-cuts and soft cheeses.
Prognosis is very poor in neonates so mothers should be immediately treated