40.Genus Listeria.

Question 1

Habitat?

Answer 1

LISTERIA

1. Habitat: • soil, sewage, • plants, • silage, • gut, • food

Question 2

Morphology?

Answer 2

2. Morphology:

• 1-2 µm thick rods, • flagella • flagella are produced on in room temperature (22 oC)

Question 3

Staining?

Answer 3

Staining: • Gram-positive

Question 4

Culture?

Answer 4

Culture:

• simple
• nutrient agar, nutrient broth,
• β haemolysis,
• 4-45 oC
• pH 5.5-9.6
• selective:
• cattle serum – trypaflavin – nalidixic acid • selective enrichment
• cold enrichment: at 4 oC • U-tube method

Question 5

Biochemistry?

Answer 5

Biochemistry:

• catalase +,
• oxidase -,
• fermentative
• virulence factors
• listeriolysin O (haemolysin): intra cellular replication • monocytosis factor: cell wall, lipoid

Question 6

Antigens?

Answer 6

Antigens:

• cell wall polysaccharide
• flagellar protein
• 13 serotypes (composite):
• most common ones: 1/2a, 4b

Question 7

Resistance?

Answer 7

Resistance:

• survives in soil for months
• propagation in soil!

Question 8

Pathogenicity?

Answer 8

Pathogenicity:

• facultative pathogenic
• virulence:
• haemolysis
• lipolysis
• monocytosis factor
• cell wall lipoids

Question 9

Pathogenicity of sheep cattle rabbit humans and birds?

Answer 9

Pathogenicity: •

sheep: • mainly encephalitis • abortion, septicaemia • cattle: • mainly abortion • encephalitis

• rabbit: • septicaemia, abortion
• humans: • abortion, newborn septicaemia, encephalitis
• birds: • septicaemia

Question 10

Species?

Answer 10

Species:

• L. monocytogenes
• L. ivanovii • stronger haemolysis, • serotype 5 • facultative intra cellular agents • several saprophytic species