Lecture 20: Yersinia spp.

What are the characteristics of Yersinia spp?

• Gram _

• Shape?

• Ferment Lactose?

• Motility?

• Unique Features?

• Gram -

  • Non-lactose fermenter

• Bipolar Rods

• Motile

  • Except for Yersinia pestis

• Psychrophilic

  • Able to withstand extreme low temperatures

What are the 4 Yersinia species of veterinary importance?

1. Y. pestis

2. Y. pseudotuberculosis

3. Y. enteriocolitica

4. Y. ruckeri

What unique feature does Yersinia spp. have when they grow on BAs?

They produce dark brown colonies due to the absorption of hemin

Yersinia pestis is a primary pathogen that causes what well known disease?

The plague

Yersinia are Psychrophilic, what does this mean?

They can grow in extremely cold temperatures

What is the optimal growth temperature for Yersinia pestis?

27°C

T/F: Yersinia pestis is zoontic

True

What is the reservoir and vector of Yersinia pestis?

• Reservoir

  • Wild rodents

• Vector

  • Rat flea

T/F: There is a human vaccine for Yersinia pestis

False

What plasmids allowed Yersinia pestis to adapt to flea-borne transmission?

• Phospholipase-D

• Pla protease

  • Cell surface protease/plasminogen activator

How did Yersinia pestis become a pandemic pathogen?

• A single amino acid modification in Pla protease

  • It caused increased invassiveness/dissemination and transmissability

Yersinia pestis contains 3 virulence plasmids unlike any other Yersinia species, what are they?

1. Plasmid pMT1

2. Plasmid pPCP1

3. Plasmid pYV

   1. Present in all Yersinia spp.

   2. Injects effector proteins called Yops into host cell

      1. Alters the cell functions and Kills PMNs and macrophagfes

4. Chromosomally encoded virulence factors

   1. High pathogenicity Island (HPI)

      1. Creates biofilm that prevent defgradation via the flea proventriculus

What are the 2 different ways that Yersinia pestis transmits via fleas?

1. Mechanical transmission

2. Biological transmission

   1. Y. pestis replicates in the flea digestive tract

      1. Dependent on the fleas ability to form a biofilm in the proventriculus (High Pathogenicity Island (HPI))

What are the different ways that humans can be infected with Y. pestis? Which is the main way?

• Bitten by an infected rodent

• Bitten by an infected flea

• Human-Human aerosol transmission

What are the 3 forms of the plague? Briefly describe each

1. Bubonic

   1. Infection of the L.Ns

   2. Most common, least fatal

2. Septicemic 

   1. Infection of the blood

   2. Can cause massive septicemia, endotoxin shock, DIC

3. Pneumonic

   1. Infections of the lungs

   2. Most severe form

   3. 100% mortality if untreated

T/F: Y. pestis is an eliminated disease

False, it is a re-emerging infectious disease

T/F: Y. pestis is endemic in some areas of the U.S

True

What is the general life cycle of Y. pestis in the US today?

Wild rodents exist as reservoirs

1. Fleas transmit Y. pestis among wild rodents

2. Humans/cats are at risk from

   1. Flea bites

   2. Rodent contact

   3. Aerosols

3. Humans are mainly infected by cats

T/F: Dogs are immune to Y. pestis

False, they are more resistant but can still be infected

What 2 wild animals were decimated by the arrival of the Sylvatic Plague in NA?

1. Prairie dogs

2. Black-footed ferrets (predator of Prairie dogs)

Black-footed ferrets almost went extinct

How did we attempt to save the black-footed ferret from Y. pestis?

Dropping vaccine-laced penut butter pellete via drones to be eaten by prairie dogs

What are signs of Feline Plague?

1. High fever

2. Vomiting

3. Tachycardia

4. DIC

5. Submandibular lymphadenopathy with a draining abscess

Why is it Important to diagnose Feline plague?

It is zoonotic and cats have very close contact to humans (cat bites can spread it to humans)

Yersinia pseudotuberculosi and Yersinia enterocolitica have what Virulence plasmid?

• Plasmid pYV

  • Type III secretion system

Yersinia enterocolitica

• Important/unique features

• Primary reservoir

• Unique Features

  • Foodborne pathogen

  • Psychrophilic (can grow at 4°C)

    • Survives in fridge for extended periods of time

• Pigs are the primary reservoirs

Yersinia pseudotuberculosis

• Species it infect?

• Gross lesions?

• Primarily a Rodent and Deer pathogen

  • Also infects cattle, humans, birds

• Micro-abscesses, abscesses, septicemia

Which Yersinia spp. is an Important food-borne pathogen?

Yersinia enterocolitica

Which Yersinia spp. causes “Yersiniosis” in deer?

• Yersinia pseudotuberculosis

  • Important disease in commercial farmed deer

What are the C.S of Yersiniosis in deer?

Severe hemorrhagic gastroenteritis

Yersinia ruckeri causes disease in what species? C.S?

• Fish (Rainbow trout and Atlantic salmon)

• Subcutaneous hemorrhaging of the mouth, fins, and eyes

Yersinia pestis, Y. pseudotuberculosis, and Y. enterocolitica are all invasive enteric pathogens transmitted by fleas. T or F?

False, Y. pestis is only flea transmission

Yersinia pestis sylvatic plague is classified by the WHO as a re-emerging infectious agent that is present only in North America. T or F?

False, it’d found a lot of places

Rodents and their fleas are important reservoirs of sylvatic plague in North America. T or F?

True

A veterinarian is only at risk of Yersinia pestis infection if bitten when handling a cat with undiagnosed plague. T or F?

False

Yersinia pseudotuberculosis is a rodent pathogen that can also infect other animals and humans. T or F?

True

Pigs are the primary reservoirs for Yersinia enterocolitica. T or F?

True