Gram + rods listeria, erysipelothrix Flashcards
Whats a good way to get yourself infected with listeria?
unpasteurized foods and lunch meat.
Crosses placenta!
What are some details about listeria?
Small, Gram + facultative anaerobic rods
What temperature range does listeria grow in?
4-44oC
Where in animals is listeria usually found?
GI Tract
How thriving is Listeria?
it is resistant to harsh environmental conditions, Ubiquitous in the environment, especially temperate zones.
how common is listeria?
it is a sporadic disease in a variety of animals including man
What does monocytogenes mean?
Can survive in macrophages
What is the most frequent Listeria species?
Listeria monocytogenes- associated with all forms of disease in multiple hosts including humans
occasionally this species of listeria is seen associated with ruminant abortion?
Listeria ivanovii
Listeria species rarely seen that is reported from CNS in ruminants?
listeria innocua
what time of year does this disease mainly affect?
Winter spring of feedlots or housed ruminants
Outbreaks of listeria usually happen when?
after feeding poor-quality silage.
Why is this disease important?
MONEY always money with seasonal occurance (winter months)
how is Listeria taken up by a host?
Ingestion or inhalation> septicemia, abortion, and latent infection.
where does listeria affect animals when absorbed through buccal cavity?
Trigeminal nerver and then brain stem
What is a poultry infection of listeria called?
septicemic listeriosis
What is the pathogenesis of Listeria?
Invasive ( direct invasion of epithelial cells) enters blood steram
Facultative intracellular bacteria: persit in macrophages
Intracellular growth leads to cell death and focal microabscesses.
How does the disease present?
Encephalitis- most common presentation in ruminants. bacteria invade oral mucosa and travel along trigeminal nerve to brainstem.
Abortion- hematogenous spread to gravid uterus, organisms penetrate the placenta and spread to fetal liver resulting in focal hepatic necrosis.
Speticemia; common in monogastrics, intracellular replication in macrophages, multifocal miliary abscess in spleen. liver. mainly occurs in neonates as a continuation of the fetal infection
What are the virulence factors of listeria?
Internalin ( gain entry to macrophages). listeriolysin O (hemolysin): required for intracellular multiplication facilitate bacterial release from phagosomes Act A: Intracellular movement (one cell to another)
L. monocytogenes uses what to travel between cells and evade antibodes?
Host actin filaments
What diseases are associated with Listeria?
Neurologic symptoms: dullness, turning or twisting of head to one side, walking in circles (circling disease)
Unilateral facial nerve paralysis with drooping of eylid and ear, drooling to pharyngeal paralyis, strabismus, nystagmus, hemiparesis, head pressing, decreased rumen motility.
Purulent endophthalmitis, usually unilateral
What lesions are associated with listeria?
Microabscesses and glial nodules infiltrated by neutrophils and gitter cells that may contain bacteria.
Acute vascular fibrinoid necrosis secondary to drainage into virchow-robin space
Leptomeningitis and densly cellular perivascular cuffs composed of lymphocytes and histiocytes with fewer neutrophils and eosinophils
neuronal necrosis
Crainial nerves may have intrafasicular and perineural accumulations of inflammatory cells (Lymphocytes, macrophages, plasma cells, and neutrophils)
what are the DDx of listeria?
pregnancy toxemia in ewes ketosis in cattle BSE thrombotic meningoencephalitis polioencephalomalacia-(thymine difficiency) sporadic bovine encephalomyelitis lead poisoning Rabies Parasitic infections Vestibular disease
How does the clinician diagnose listeria ante-mortem?
CNS disease Presumptive Dx from symptoms Listeria enrichment culture Gram stained CSF sediment short intracellular and extracellular Gram + bacteria Septicemia culture of liver and spleen
