Listeria and Erysipelothrix Flashcards
what does Listeria monocytogenes look like under a microscope with a gram stain?
gram positive short rod
what are the reservoirs of Listeria monocytogenes?
soil
gastrointestinal tract of carriers (animals and humans)
what are the common modes of transmission for Listeria monocytogenes?
horizontal: fecal-oral
vertical: placenta, vaginal fluids
how can the host shed Listeria moncytogenes?
feces
urine
milk
uterine fluids
aborted fetuses
nasal discharge
what is the most frequently recognized form of listeriosis?
listeric (meningo) encephalitis in adult ruminants
what is the mortality rate of listeric (meningo) encephalitis?
50-70%
what characterizes the neurologic signs of listeric (meningo) encephalitis usually?
unilateral
localize to brain stem
affect cranial nerves
what is the pathogenesis of listeric encephalitis?
eat contaminated food
Listeria monocytogenes enters abrasions in oral cavity
track trigeminal nerve
brainstem
necrosis and neutrophilic microabscesses
what are some differential diagnoses for listeric encephalitis?
thromboembolic meningoencephalitis due to Histophilus somni
cerebral abscess due to other bacteria
rabies
what does listeric abortion usually occur in?
small ruminants
what is the primary site of infection of Listeria monocytogenes with listeric abortion?
uterus, placenta
abortion of autolyzed fetus
who does septicemic listeriosis occur in?
primarily very young animals
what are the clinical signs of septicemic listeriosis?
fever
depression/lethargy
injected mucous membranes
+/- hemorrhagic gastroenteritis in calves
what is the target organ of septicemic listeriosis?
liver: hepatic necrosis
what diagnostic samples can be taken for listeric abortion?
culture, cytology of abomasal contents from fetus
histopath and gram stain liver, spleen, lungs
what are the well known Listeria monocytogenes virulence factors?
listeriolysis O=LLO
actin comet tails
is Listeria a reportable disease?
yes
who does swine erysipelas impact?
growing and adult swine
up to ______ of pigs in intensive swine production areas are asymptomatic carriers of Erysipelothrix rhusiopathiae
50%
where do carriers of Erysipelothrix rhusiopathiae harbor it?
tonsils and shed in oronasal secretions and feces
what is the virulence factor of Erysipelothrix rhusiopathiae?
neuraminidase
what characterizes the acute form of erysipelas?
septicemia
fever
skin lesions (diamond)
what characterizes the chronic form of erysipelas?
arthritis
vegetative valvular endocarditis
what are the differential diagnoses for erysipelas (diamond skin disease in swine)?
septicemia due to Salmonella, Streptococcus suis
classical swine fever
glasser’s disease
how is diamond skin disease controlled?
vaccine
what can you see with erysipelas in poultry?
sudden death (septicemia)
swollen joints
endocarditis
is erysipelas zoonotic?
yes
who can carry erysipelas (poultry) in semen?
toms (male turkeys)
how is erysipelas prevented in poultry?
antibiotics
vaccine
how does thromboembolic meningoencephalitis due to Histophilus somni differ from listeric encephalitis?
Histophilus spp does not have a preferred site of infection in the brain
distinguish by other lab tests
how do cerebral abscesses due to other bacteria differ from listeric encephalitis?
Listeria: usually unilateral cranial nerve signs
cerebral abscess: mentation changes
how can you differentiate rabies from listeric encephalitis?
rabies usually reflects damage to cortical neurons: mentation changes
not unilateral
does metritis from listeric abortion have effects on subsequent reproduction?
no
how long can Listeria be shed in vaginal secretions and milk?
a month
what makes Listeria monocytogenes hard to get rid of?
persists in environment, food, and gastrointestinal tract
likes low temperatures
resistant to drying and heat
tolerates wide pH range
what does listeriolysin O do?
allows Listeria to escape phagosome and then replicate in cytoplasm
pore-forming protein toxin
what do actin comet tails allow Listeria to do?
hijack and polymerize actin to move and hide
what is the host response to Listeria moncytogenes?
cellular necrosis and neutrophilic inflammation
who is clinical disease of Listeria seen in usually?
ruminants
how do humans usually get listeriosis?
food
what does neuraminidase from Erysipelothrix rhusiopathiae do?
important for attaching and invading
cleaves sialic acid
+/- nutrional requirements, disruption host functions
what are the forms of Erysipelas in swine?
acute
chronic
