Lecture 9: Listeria monocytogenes and Erysipelothrix rhusiopathiae

List the general features of Listeria monocytogenes

• Shape

• Gram Staining

• Catalase _

• Oxidase _

• Hemolysis _

• Motility _

• CAMP test _

• Small Gram + short rods (bacillus)

• Catalase +

• Oxidase -

• Beta hemolysis 

  • Small zone

• Motile

  • Multiple flagella

  • Umbrella-shape in SIM

• CAMP +

T/F: Listeria monocytogenes grows on McConkey agar

False, it is Gram + so it won’t

T/F: Listeria monocytogenes are environmental saprophytes

True

What are the 3 main types of Listeria monocytogenes serotypes?

1. 1

2. 2

3. 4b

How does Listeria monocytogenes enter the animal? How does it travel through the body once it enters?

• Through ingestion of contaminated feed 

  • Penetrates the intestine, then spreads through the lymph and vasculature

  • or

  • Enters via dental pulp and the migrates via cranial nerves

  • or

  • Transplacentally in pregnant animals

The way L. monocytogenes enters the animal can influence the type of listeriosis that manifests

Listeria monocytogenes utilize what type of replication style?

• They are facultative replicators

  • That means they can replicate in or out of the cell

To enter the cell, L. monocytogenes uses cell invasion proteins known as ……

Internalins A and B (Inl A/B)

How does L. monocytogenes escape/avoid immune destruction?

• Through escaping the phagosome once uptaken

  • Uses membrane damaging toxins listeriolysin and phospholipases

Once L. monocytogenes escapes the phagosome and replicates within the cell, how does it spread from cell-to-cell?

• ActA

  • ActA induces host Actin to polymerize around L. monocytogenes and form actin comet tails

  • The bacteria then uses this actin to spread from cell-to-cell

What are the 3 main sources of L. monocytogenes infections in animals?

1. Poorly preserved/rotten silage (ph>5)

   1. aka Silage disease

   2. Often seen in winter or spring

      1. Animals are feed silage that was not properly fermented

2. Asymptomatic carriers

3. Biofilms on equipment/environment

Listeriosis infections can present as 4 different forms, what are they?

1. Abortion/perinatal mortality

2. Septicemia

   1. Neonatal ruminants and monogastrics

3. Meningoencephalitis

   1. Adult ruminants

4. Keratoconjunctivitis and mastitis

   1. Rare

How would you expect listeriosis to present in an adult ruminant vs a neonatal ruminant?

• Adult Ruminant

  • Meningoencephalitis

• Neonatal Ruminant

  • Abortion or Septicemia

Neural listeriosis is caused by L. monocytogenes entering the host via the dental pulp/oral mucus and then entering the C.Ns to reach the brain, what are the lesions associated with this form of Listeriosis?

• Marked hyperemia of B.V of leptomeninges

• Micro-abscesses

• Perivascular cuffing of mononuclear cells (lymphocytes, plasma cells)

  • Accumulation of inflammatory cells in the space around a blood vessel

Sheep/Goats that present with

• Dullness

• Circling

• Tilting of the head

• Drooling

• Drooping eyelid/ear

Likely have…….

Neural listeriosis

Sheep that die as a result of L. monocytogenes that became septic, usually present with what lesions?

Multifocal Hepatic necrosis (pyogranulomatous)

What is Silage eye? What are it’s clinical signs?

• Ocular form of listeriosis

• Associated with eye trauma

• Clinical Signs

  • Uni/bilateral hyperaemic conjunctiva 

  • Cloudy cornea

  • Lacrimation

How is L. monocytogenes diagnosed?

Bacterial Isolation

T/F: L. monocytogenes grows on McConkey agar

False, it’s Gram + so it won’t

Listeria selective enrichment broth improves isolation for samples taken from the ____, what is selective about this broth?

Brain, cold (4C)

How is L. monocytogenes treated? Is it always effective?

• Penicillin and tetracyclines

  • Usually not effective for neural listeriosis

How do humans usually get listeriosis?

• Indirectly via zoonotic infections

• Transmission during pregnancy

What is the disease of red threads?

Erysipelothrix rhusiopathiae

List the general features of Erysipelothrix rhusiopathiae

• Shape

• Gram Staining

• Catalase _

• Oxidase _

• Coagulase _

• Hemolysis _

• Motility _

• Short curved bacilli

• Gram -

• Catalase -

• Oxidase -

• Coagulase +

• Alpha hemolytic 

• Non-motile

T/F: Erysipelothrix rhusiopathiae is zoonotic

True

Erysipelothrix rhusiopathiae causes what cutaneous disease in pigs?

Diamond skin disease

What clinical signs is Erysipelothrix rhusiopathiae known to cause in turkeys?

• Arthritis 

• Valvular endocarditis

_____ are the most important reservoir of Erysipelothrix rhusiopathiae

Pigs

Infected and carriers of Erysipelothrix rhusiopathiae shed bacteria in ____ and ____

Feces, secretions

Erysipelothrix rhusiopathiae enters into the host through the _____, ___, or ____ _____

Tonsils, skin, mucus membranes

Name and described the 3 most important virulence factors to Erysipelothrix rhusiopathiae

1. Capsule

   1. Antiphagocytic

   2. Facilitates intracellular replication

2. Hyaluronidase

   1. Aids with dissemination into tissues

3. Neuraminidase

   1. Adherence and invasion of endothelial cells

   2. Damages vascular endothelial cells

T/F: Erysipelothrix rhusiopathiae can cause vasculitis and thrombus formation

True!

Arthritis and Vegetative endocarditis are examples of the ____ form of Erysipelothrix rhusiopathiae disease in swine

chronic

How would acute or subacute Erysipelothrix rhusiopathiae present in pigs?

• Septicemia with sudden death

• Diamond Skin Disease

Which serotypes of Erysipelothrix rhusiopathiae are most common in pigs and are the targets of vaccines against this bacteria?

Serotypes 1 and 2

How does Erysipelothrix rhusiopathiae present in young and adult sheep?

• Young

  • Non-suppurative polyarthritis

    • Caused by AG/ABs deposits in joints

• Adult

  • Post-dipping lameness

    • Same idea, AB/AG deposits in joints, in this case the sheep are exposed by the dipping pools

Which bacteria causes rhomboid-shaped skin lesions in dolphins?

Erysipelothrix rhusiopathiae

T/F: You can use porcine vaccines to prevent Erysipelothrix rhusiopathiae infections in cetaceans (dolphins, porpoises, whales)

True!

Erysipelothrix rhusiopathiae is a zoonotic pathogen, define the term Erysipeloid

• A localized skin infection caused by Erysipelothrix rhusiopathiae

  • Also known fish handler’s disease

T/F: Listeria monocytogenes spreads between host cells by including the formation of host cell actin comet tails

True

T/F: Listeria monocytogenes brain lesions are characterized by microabscesses due to mononuclear infiltrates

False, the micro-abscesses are caused by neutrophils

Silage disease in ruminants caused by Listeria monocytogenes is due to spoiled silage with a pH<5

False, it would be caused by a pH>5 (alkaline)

T/F: Properly refrigerated cooked meats are not a risk for listeriosis in humans

False

T/F: Erysipelothrix rhusiopathiae does not survive for extended periods in the environment

False

T/F: Pigs are the most important reservoir of Erysipelothrix rhusiopathiae

True

T/F: Erysipelothrix rhusiopathiae septicemia produces rhomboid skin lesions in pigs because of vasculitis and thrombosis

True