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Listeria Flashcards

1
Q

Is listeria gram positive or negative?

A

Gram positive rods- usually occur in chains

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2
Q

Catalase _____ Oxidase_____

A

catalase positive oxidase negative

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3
Q

Is listeria host specific?

A

no- it can affect a lot of different species Critical species to know- Ruminants

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4
Q

True/False: Listeria is spore forming and non motile?

A

False! Listeria is non spore forming and motile

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5
Q

What kind of flagella does Listeria have?

A

peritrichous

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6
Q

Is listeria an anerobe or aerobe?

A

Facultative anaerobe

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7
Q

What are the two most important pathogen species?

A

Listeria monocytogenes( MOST IMPORTANT) and Listeria invanovii

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8
Q

How do you distinguish between L. monocytogenes and L. invanovii?

A

CAMP test! L. monocytogenes- CAMP positive with S. aureus L. invanovii- CAMP positive with R. equi

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9
Q

Listeria are facultative _____ parasites

A

intracellular- survival in macrophages or hepatocytes

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10
Q

What pathogenesis does Listeria cause?

A

septicemia, encephalitis, and abortions

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11
Q

What does ActA do?

A

intracellular movement

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12
Q

What are Internalins?

A

induces phagocytosis- aids in phagocytosis and allows the bacteria to live in the cellular environment

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13
Q

What are the adhesions of listeria?

A

internalins, ActA, and protein 60

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14
Q

What is the main virulence factor of Listeria and what does it do?

A

Listeriolysin O

VERY IMPORTANT

  • can induce apoptosis of the cell- lysis of ferritin vacuoles

pore forming lysis factor. They create pores and the bacteria gets into the phagosome. To get out of the phagosome, Listeria punches a hole in the membrane and is able to escape. Then the bacteria uses ActA to travel through the cytoplasm to the next cell

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15
Q

What is a cellular product of Listeria that breaks down phospholipids for membrane lysis?

A

Phospholipase C

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16
Q

How does Listeria surivie in the intestinal lumen?

A

Bile salt hydrolase

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17
Q

Does Listeria have variability?

A

YES! very high variability. Many serovars

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18
Q

What is the normal habitat for Listeria?

A

Decaying plant matter

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19
Q

How is Listeria transmitted?

A

Fecal oral route

Ingestion of contaminated feed

nasal mucosa

20
Q

How do ruminants get Listeria?

A

When they eat poor quality silage that has fermented and decayed

21
Q

Intestinal Pathogenesis for Listeria

A
  1. bacteria is ingested in decaying soil
  2. Many are killed by gastric acids
  3. If they survive, attach to epithelium, M cells, and phagocytic cells
  4. Once in the phagocytes, they move through the blood stream
22
Q

Central Nervous System pathogenesis for Listeria

A
  1. damaged oral, nasal or ocular mucosa
  2. Bacteria goes into the facial nerves (trigeminal) and gets into the CNS
23
Q

What can listeria cause in Pregnant females?

A

abortion or calves will be born with CNS signs- this is deterined by host immunity

24
Q

How can you tell if Listeria has gotten into the CNS?

A

do a cerebrospinal tap- fluid will be cloudy due to tons of inflammation

You will see tons of mononuclear cells

Perivascular cuffing

25
What will septicemic Listeria cause?
necrosis in the liver and spleen
26
What is the main pathology that Listeria causes in Ruminants?
Encephalitis (Circling disease) The bacteria is causing damage to the brain tendency to circle in one direction Facial paralysis Death in 2-3 days
27
Is treatment of Encephalitis in ruminants effective?
Not really- by the time you see signs there is already too much damage to the brain
28
What are some characteristics of Encephalitis?
perivascular cuffing: a lot of inflammatory cells around the vessels
29
What does Listeria cause in ruminants?
Septicemia- if bacteria in GI tract Abortion- not common (sporadic, localize in placenta) Conjunctivits- related to elevated feed bunkers Mastitis
30
What can Listeria cause in the liver?
31
When are horses susceptible to getting Listeria septicemia?
When there has been failure of passive transfer
32
What happens if dogs, cats, or swine get Listeria?
Very mild, often asymptomatic
33
How does Listeria cause outbreaks in humans?
Food borne disease meningitis is the most common manifestation pregnant women- still births, preterm labor, infant with systemic infection
34
What products may humans ingest that are contaminated?
dairy products that are infected with listeria from and asymptomatic cow Listeria can withstand refrigeration
35
What seaons are more typical to see Listeria
winter and spring- can withstand cold temperatures Can survive in silage even during a freeze
36
When an animal is _____ the bacteria has an easier time getting into the host and causing disease
stressed
37
Who are predisposed to disease from Listeria?
humans- immunosupressed animals- neonates and preganat animals
38
What kind of immune response do we want against Listeria?
mainly cell mediataed- since bacteria lives in cells humoral can play a role
39
Is there a vaccine for Listeria?
No
40
What will you see in a gram stain of Listeria
Gram positive short rods with rounded ends. Some cells may be curved
41
What different medias can you use to isolate Listeria?
Listeria enriched media- Columbia CNA agar, Oxford medium Sheep Blood agar at 35 degrees celsius- cold enrichment. Casues a narrow zone of Beta hemolysis Grows best with increased CO2
42
Is Listeria CAMP positive or negative?
positive with Staph aureus
43
What low temperature is Listeria still mobile at?
25 degrees celsius Umbrella pattern of motility
44
How do you treat Listeria?
antimicrobial treatment There are NO vaccines Therapy is often of little use
45
How do you control Listeria?
Don't feed bad silage reduce stress isolation of affected animals

MY Bacteriology exam 2 (18 decks)

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