Listeria Flashcards
1
Q
What are the characteristics of the listeria bacteria?
A
- Gram positive, Rod-Shaped bacterium
- Non-Spore forming
- Motile
- Faculative anaerobe
- Growth is enhanced with 10% CO2
- Grows at low temperatures (4 degrees)
2
Q
What are the main ways listeria can spread?
A
- Faecal-Oral route
- Abrassions in the buccal cavity
- Soil-Borne
- Contaminated Silage
- Unpasteurised Cheese
- Unpasteurised Milk
- Contaminated Vegetables
3
Q
What two things aid the multiplication of listeria in silage?
A
- Low levels of iron and high pH
4
Q
What three ways can you culture listeria?
A
- Sheep Blood agar
- Nutrient Agar
- Listeria Selective Media
5
Q
At what temperature can listeria survive and multiply in the environment?
A
4 degrees
6
Q
What does L. monocytogenes cause?
A
- Neural listeriosis
- Abortion
- Iritis
- Systemic Disease
7
Q
What does L. ivanovii cause?
A
Abortion
8
Q
What is the virulence of listeria?
A
- Penetrates the epithelial barrier in the gut and multiplies in liver/ spleen macrophages
- May enter the CNS and acsue neurological signs
- replicates at low temp
- Iron acquisition mechanism
- Animals fed silage may be predisposed
- Adapts to survive in different conditions
- excellent survival and replication
- haemolysin- O?
9
Q
What is the pathogenesis of Listeria?
A
- Enters through abrasions in the buccal or nasal mucosa
- Can penetrate the epithelial barrier in the intestine
- Enters nerve fibre, primarily 5th or 7th and is then transported to the brain stem
10
Q
What are the three different forms of listeriosis?
A
- Neurological
- Visceral
- Abortive
11
Q
What are the clinical signs of listeria in sheep and goats?
A
- Septicaemia- visceral listeriosis
- Neural (Circling disease)
- Abortion
- Iritis
12
Q
What samples would you collect for diagnosis
A
- visceral form- liver, kidney and spleen
- neural form- spinal fluid, brain stem, medulla
- abortion- placenta (cotyleodns), foetal abomasal contents, uterine discharge and afterbirth
13
Q
How may you treat listeriosis?
A
- High doses of antibiotics to acheive the appropriate brain concentration
- Recovery rate in sheep can be up to 30%
- Propylene glycol or concentrated oral rehydration solution containing dextrose should be administered
- Fresh palatable food and water should always be available
14
Q
How would you treat iritis?
A
topical antibiotic ointment
15
Q
How do you control the silage feeding?
A
- Discard spoiled silage
- Clean feed troughs
- avoid soil/ manure contamination
- discard refusals
- clean water
