Listeria

What is the gram stain and shape of L. monocytogenes? Does it form spores?

G+

Rods

Non spore forming

L. monocytogenes is _ -hemolytic but often produce only _____ zones of hemolysis

β

narrow

L. monocytogenes is CAMP (positive/negative)

positive

L. monocytogenes synthesize ____ flagella at room temperature (20−25 °C),not at ______ _____

peritrichous

body temperatures

L. monocytogenes has umbrella motility and is micro-aerophilic. What does it mean to be micro-aerophilic?

grows well with a little bit of O2

T/F L. monocytogenes is a foodborne pathogen that can grow at 4 F

Fasle, 4 C

T/F The overall mortality rate of L monocytogenes infection is 15%-20%,

True

If a pregnant animal gets L monocytogenes, what happens to the mother and fetus?

USUALLY fetal loss or neonatal death, but mothers usually survive

T/F L. monocytogenes fatality rate can be as high as 100% in livestock

True

Where are some of the places that you can find L. monocytogenes?

Feces

Tissues: tonsils and lymph nodes

Soil, water and vegetation

What is one of the main modes of infection for L. monocytogenes?

silage

T/F Silages (pH> 4.5) had L. monocytogenes more than with lower pH

True

What are the FOUR virulence factors for L. monocytogenes?

Internalin

Listeriolysin (LLO)

Phospholipase C

Act A

Match each of the following virulence factor to its description:

Internalin:

Listeriolysin (LLO):

Phospholipase C:

Act A:

membrane associated protein is responsible for internalization

polymerization of actin molecules

allows escape from the phagosome

hemolysin

Internalin: membrane associated protein is responsible for internalization

Listeriolysin (LLO): hemolysin

Phospholipase C: allows escape from the phagosome

Act A: polymerization of actin molecules

What are the FOUR forms of Listeriosis in ruminants?

CNS infection

Abortion

Septicemia

Mastitis

With the CNS form:

• Meningoencephalitis in _____

• ______ in pre-ruminant calves

• adult

• meningitis

When is the common time of year that you will see Listeriosis in ruminants?

winter or early spring (silage)

You have a cow that comes in that has depression, drooping ears, holds the head to one side, protrusion of the tongue, salivation, paralysis of the face.

What are these clinical signs in line with?

Listeriosis: CNS form

The CNS form of Listeriosis is:

____ disease

Progresses to complete ___

Death in _-_ ____

Circling

paralysis

2 or 3 days

Will you see septicemia with the CNS form of Listeriosis? How does the bacteria travel?

no

through nerves

What is the main nerve that the CNS form travels through?

Trigeminal nerve from the oral cavity

The CNS form has ___ gross lesions, ____ and _____ cell infiltration. What is something that you can see?

no

PMN

mononuclear

Perivascular cuffing

What happens in the abortion form of Listeriosis?

Placentitis

Abortion in the late term

(and no other signs)

You have a young ram that comes in. It is depressed, has dyspnea, salivation, nasal discharge, and lacrimation. You do some diagnostic testing and find focal necrosis of liver, spleen, and lymph nodes.

What do you think is wrong with the ram?

Septicemic Listeriosis

T/F Listeriosis is rare in pigs, dogs, cat

True

What form do horses and chickens normally get

Horses: septicemic form

Chickens: encephalitis

When diagnosing:

History

Clinical Signs

Lesions

Culture examinaion

History: Silage feeding

Clinical signs: Neurological

Lesions: Perivascular cuffing

Cultural examination: Brain, blood, milk, placenta and fetus

What TWO animals are not treated due to cost and the fact that they can become subclinical?

cattle and sheep

What is used to treat Listeria in humans?

penicillin and gentamicin

What type of vaccine is there for listeria and where is it used at?

live attenuated; used in Europe and Australia

How does one control Listeria? (4)

1. Not feeding spoiled silage!

2. Isolation of sick animals

3. Quick disposal of dead animals

4. Disposal of contaminated bedding