Lesson 4c: Listeria species

Question 1

Listeria species

Answer 1

• most are small, gram-positive, coccobacillary rods, up to 2 um in length
• catalase-positive, oxidase-negative, motile, facultative anaerobes
• environmental saprophytes
• grow on non-enriched media
• tolerate wide temperature and pH ranges
• small haemolytic colonies on blood agar
• tumbling motility at 25°C
• Aesculin hydrolysed
° outbreaks of listeriosis often related to silage feeding
• pathogenecity associated with intracellular replication

Question 2

aesculin hydrolysed

Answer 2

listeria species

Question 3

has the ability to invade both phagocytic and non-phagocytic cells, to survive and replicate intracellularly and to transfer from cell to cell without exposure to humoral defence mechanism

Answer 3

L. monocytogenes

Question 4

ingestion of feed contaminated with L. monocytogenes results to?

Answer 4

septicaemia, encephalitis or abortion

Question 5

in pregnant animals, infection results in?

Answer 5

transplacental transmission

Question 6

it destroys the membranes of phagocytic vacuoles allowing listeria to escape into the cytoplasm.

Answer 6

cytolytic toxin, listeriolysin, phospholipase enzyme

Question 7

produced by the organism, directs the formation of tail-like structures from host cellular microfilaments which aid the motility of the invading pathogens thereby inducing pseudopod-like projections which are taken up by adjacent cells and replicate infection

Answer 7

actin-polymerizing protein ( ActA)

Question 8

Another way of L. monocytogenes to survive within the host cells is by?

Answer 8

inhibiting CELL AUTOPHAGY

Question 9

are present as encephalitis, abortion, septicaemia or endophthalmitis in ruminants.

Answer 9

Bovine Listeriosis

Question 10

(14-40 days) are dullness, circling and tilting of the head unilateral facial paralysis

Answer 10

neural listeriosis

Question 11

only has 2-3 days incubation period

Answer 11

septicaemia listeriosis