Listeria Flashcards
Is listeria gram positive or negative?
Gram positive rods- usually occur in chains
Catalase _____ Oxidase_____
catalase positive oxidase negative
Is listeria host specific?
no- it can affect a lot of different species Critical species to know- Ruminants
True/False: Listeria is spore forming and non motile?
False! Listeria is non spore forming and motile
What kind of flagella does Listeria have?
peritrichous
Is listeria an anerobe or aerobe?
Facultative anaerobe
What are the two most important pathogen species?
Listeria monocytogenes( MOST IMPORTANT) and Listeria invanovii
How do you distinguish between L. monocytogenes and L. invanovii?
CAMP test! L. monocytogenes- CAMP positive with S. aureus L. invanovii- CAMP positive with R. equi
Listeria are facultative _____ parasites
intracellular- survival in macrophages or hepatocytes
What pathogenesis does Listeria cause?
septicemia, encephalitis, and abortions
What does ActA do?
intracellular movement
What are Internalins?
induces phagocytosis- aids in phagocytosis and allows the bacteria to live in the cellular environment
What are the adhesions of listeria?
internalins, ActA, and protein 60
What is the main virulence factor of Listeria and what does it do?
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
What is a cellular product of Listeria that breaks down phospholipids for membrane lysis?
Phospholipase C
How does Listeria surivie in the intestinal lumen?
Bile salt hydrolase
Does Listeria have variability?
YES! very high variability. Many serovars
What is the normal habitat for Listeria?
Decaying plant matter
How is Listeria transmitted?
Fecal oral route
Ingestion of contaminated feed
nasal mucosa
How do ruminants get Listeria?
When they eat poor quality silage that has fermented and decayed
Intestinal Pathogenesis for Listeria
- bacteria is ingested in decaying soil
- Many are killed by gastric acids
- If they survive, attach to epithelium, M cells, and phagocytic cells
- Once in the phagocytes, they move through the blood stream
Central Nervous System pathogenesis for Listeria
- damaged oral, nasal or ocular mucosa
- Bacteria goes into the facial nerves (trigeminal) and gets into the CNS
What can listeria cause in Pregnant females?
abortion or calves will be born with CNS signs- this is deterined by host immunity
How can you tell if Listeria has gotten into the CNS?
do a cerebrospinal tap- fluid will be cloudy due to tons of inflammation
You will see tons of mononuclear cells
Perivascular cuffing
What will septicemic Listeria cause?
necrosis in the liver and spleen
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
Is treatment of Encephalitis in ruminants effective?
Not really- by the time you see signs there is already too much damage to the brain
What are some characteristics of Encephalitis?
perivascular cuffing:
a lot of inflammatory cells around the vessels
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
What can Listeria cause in the liver?
When are horses susceptible to getting Listeria septicemia?
When there has been failure of passive transfer
What happens if dogs, cats, or swine get Listeria?
Very mild, often asymptomatic
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
What products may humans ingest that are contaminated?
dairy products that are infected with listeria from and asymptomatic cow
Listeria can withstand refrigeration
What seaons are more typical to see Listeria
winter and spring- can withstand cold temperatures
Can survive in silage even during a freeze
When an animal is _____ the bacteria has an easier time getting into the host and causing disease
stressed
Who are predisposed to disease from Listeria?
humans- immunosupressed
animals- neonates and preganat animals
What kind of immune response do we want against Listeria?
mainly cell mediataed- since bacteria lives in cells
humoral can play a role
Is there a vaccine for Listeria?
No
What will you see in a gram stain of Listeria
Gram positive short rods with rounded ends. Some cells may be curved
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
Is Listeria CAMP positive or negative?
positive with Staph aureus
What low temperature is Listeria still mobile at?
25 degrees celsius
Umbrella pattern of motility
How do you treat Listeria?
antimicrobial treatment
There are NO vaccines
Therapy is often of little use
How do you control Listeria?
Don’t feed bad silage
reduce stress
isolation of affected animals
