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My Packs: (UWO) (MICROIMM 2500) > (Section C: Bacteriology) Lecture 19: > Flashcards

(Section C: Bacteriology) Lecture 19: Flashcards

1
Q

Describe:

Yersinia
* Gram stain
* Shape
* Strains

A
  • Gram negative
  • Rod shaped
  • Bacteria
  • 3 strains pathogenic to humans
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2
Q

What are the 3 strains of Yersinia that are pathogenic for humans?

A
  1. Y. enterocolitica
  2. Y. pseudotuberculosis
  3. Y. pestis
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3
Q

Y. enterocolitica

A

Causes “yersiniosis” - a rare cause of diarrhea and abdominal pain

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4
Q

Y. pseudotuberculosis

A

Primarily an animal pathogen that can cause tuberculosis-like symptoms in animals, enteritis in humans

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5
Q

Y. pestis

A

Cause of the plague

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6
Q

What are key characteristics of Yersinia pestis?

A
  • Extraordinarily virulent pathogen
  • May cause death in 2-4 days by sepsis and/or overwhelming pneumonia with respiratory failure
  • NOT an efficient colonizer of humans
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7
Q

History of Yersinia pestis discovery and namesake

A
  • Discovered by Alexandre Yersin (namesake) and Kitasato Shibasaburo in the late 1800s
  • Pestis = Pestilence (contagious or infectious epidemic disease)
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8
Q

Plague:

  1. Incubation period
  2. Death period
A
  1. 3-7 days
  2. 2-4 days
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9
Q

Plague:

General signs and symptoms (early stage)

A

Sudden onset of:
1. Fever
2. Chills
3. Headaches
4. Muscle pain
5. Weakness

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10
Q

Plague:

Signs and symptoms (lymph nodes)

A

Painful swellings (buboes) of lymph nodes in:
* Armpits
* Legs
* Neck
* Groin

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11
Q

Plague:

Signs and symptoms (late stage)

A
  • High fever
  • Delirium
  • Mental deterioration
  • Large blackish pustules that burst
  • Vomiting of blood
  • Bleeding in the lungs
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12
Q

What were the 3 plague pandemics?

A
  1. “Plague of Justinian”
  2. “Black Death”
  3. Mid 19th Century
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13
Q

Plague of Justinian
* Date
* Cause
* Area
* Death

A
  • Started in the 6th century (541-542 AD)
  • Caused by Yersinia pestis
  • Mediterranean, Italy and throughout Europe
  • ~50% of population died, around 100 million people killed
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14
Q

What happened after the initial plague during the “Plague of Justinian”?

A

Continued in cycles for 200 years until 750 AD
* Disappears for ~800 years

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15
Q

Black Death
* Date
* Cause
* Area
* Death

A
  • Late 1340s (spread to Europe)
  • Caused by Yersinia pestis
  • Originated in Asia, reached Europe in late 1340s
  • ~100 million globally, ~25 million Europeans (1/3 of population)
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16
Q

What was society’s reaction to the Black Death during its time?

A
  • No idea what was going on
  • No (real) treatment
  • Believed it was “God’s anger” or “Satan’s influence”
  • Persecuted strangers, minorities, and witches
  • European social order and such was destroyed
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17
Q

What was the Feudal System?

A

Political and social structure prevalent in Europe at the time of the Black Death
* Little opportunity for advancement
* Few people had everything, most had little

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18
Q

What did the Black Death do to the Feudal System?

A

Created vacant towns and farms (positions of authority need to be filled)
* Created new opportunities for the peasants

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19
Q

How was it discovered that Y. pestis caused the Black Death?

A

Analyzing genomes in the feet of bodies buried in London

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20
Q

Mid-19th Century Pandemic
* Date
* Cause
* Area
* Deaths

A
  • 1850s, considered active until 1959
  • Caused by Yersinia pestis
  • Started in China, spread to US in 1900
  • 12 million deaths in China and India alone
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21
Q

Pathogenesis of Yesinia pestis:
* Where does it live?
* What type of pathogen is it?
* Describe mechanism it transfers by

A
  • Lives in rodents and are transmitted by fleas
  • Zoonotic pathogen

Mechanism of transfer
* Causes “blocking” in the flea (biofilm formation in the proventriculus)
* Causes fleas to “starve”
* Fleas regurgitate bacteria into organisms it feeds on

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22
Q

What is the infective dose of Yersinia pestis?

A

~10 cells
* Very infective, many bacteria require hundreds of cells to cause infection

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23
Q

Where does Yersinia pestis initially survive and grow?

A

In innate immune cells

24
Q

Where does Y. pestis replicate?

A

In lymphoid organs
* Spleen
* Bone marrow
* Lymph nodes
* Liver

25
Q

What are buboes?

A

Swelling of lymph nodes
* Caused by Yersinia pestis

26
Q

Y. pestis kills —- and continues to grow —–

A
  • Macrophages
  • Extracellularly
27
Q

In the terminal stage of disease caused by Yersinia Pestis, what is the characteristic?

A

High concentrations of bacterial cells in blood

28
Q

Why is the high concentration of bacteria in blood essential for transmission of Y. Pestis?

A

Fleas take blood meal (thus bacteria) and will transfer to other organisms when feeding

29
Q

How does Y. pestis overcome immune defense mechanisms?

A

Can evade mammalian innate immune response
* Allows for infection prior to an immune response

30
Q

What are the major virulence factors for Y. pestis?

A
  1. Type III secretion
  2. Phospholipase
  3. Plasminogen activator
  4. Yersiniabactin
  5. Mutated LPS
31
Q

What is Type III secretion typical for?

A

Gram negative intracellular pathogens

32
Q

What is phospholipase essential for in Y. pestis?

A

Survival in the flea

33
Q

What is the purpose of the plasminogen activator in Y. pestis?

A

Clot buster
* Bursts clots to allow for spread of the bacteria (dissemination)

34
Q

What is Yersiniabactin?

A

Iron binding siderophore
* Gets iron nutrient for the bacteria

35
Q

What does a mutated LPS structure mean for Y. pestis?

A

The immune system cannot recognize the LPS structure, thus the excessive inflammation response occurs

36
Q

How do Type III secretion systems work?

A

Secrete virulence factors (effectors) directly into host cells across host cell membrane

37
Q

What are effectors? What is their function?

A

Virulence factors secreted in Type III secretion systems
* Function to ‘poison’ the host cell by targeting host cell signaling pathways

38
Q

What did Y. pestis evolve from?

A

Y. pseudotuberculosis

39
Q

True or False:

Y. pestis can survive in animal intestine

A

False, Y.pestis cannot survive well in the animal intestine

40
Q

Why is the Y. pestis LPS molecule weakly recognized by the innate immune system?

A

A mutation in Lipid A modifying enzyme

41
Q

What plasmid do all pathogenic Yersinia contain?

A

pYV
* Encodes type III secretion system

42
Q

What are the 3 major forms of the Plague?

A
  1. Bubonic
  2. Septicemic
  3. Pneumonic
43
Q

Bubonic Plague
* Transmission
* Signs/Symptoms
* Mortality

A
  • Transmitted by flea bites
  • Painfully swollen lymph nodes (“buboes”) in groin, armpits and neck
  • 40-60% mortality if untreated
44
Q

Which form of the plague is the most common?

A

Bubonic

45
Q

What can bubonic plague develop into?

A

Septicemic and pneumonic plagues

46
Q

Septicemic Plague
* Transmission
* Signs/Symptoms
* Mortality

A
  • Fleas
  • Presence of Y. pestis is systemic (in the blood)
  • Experience gangrene and disseminated intravascular coagulation
  • 50-90% mortality if untreated
47
Q

Pneumonic Plague
* Transmission
* Signs/Symptoms
* Mortality

A
  • Aerosols directly into lung, or from septicemic plague
  • Coughing up blood
  • 95-100% mortality if untreated
48
Q

What is unique about pneumonic plague?

A
  • Most dangerous
  • Short incubation
  • Treatment must be within first 24 hrs of symptoms for patient to survive
49
Q

What are the 4 routes of transfer for human disease of Y. pestis?

A
  1. Flea bite
  2. Inhalation from humans/animals
  3. Handling infected animals (skin contact, scratch, bite)
  4. Ingesting infected meat
50
Q

What is the most common route for human disease of Y. pestis?

A

Flea-bite

51
Q

How does Y. pestis transmission occur historically and present-day?

A

Historically: Rat-borne urban epidemics
Present-day: Wildlife associated plague with sporadic outbreaks

52
Q

What is done in diagnosis of Y. pestis?

A
  • RAPID
  • Culture and identification from bubo aspirate, sputum, blood may take 4 days
  • Stains and rapid antigen tests (in endemic regions)
53
Q

What is important in the treatment of pneumonic plague patients?

A

Isolation
* Very contagious and deadly

54
Q

How is Y. pestis treated/prevented?

A
  • Human cases treated with appropriate antibiotics including prophylaxis to exposed individuals
  • Insecticides are used to kill fleas
55
Q

What is Y. pestis identified as in the Centers for Disease Control and Prevention?

A

Category A

56
Q

What defines a Category A organism?

A
  • Can be easily disseminated or transmitted from person to person
  • Result in high mortality rates and have the potential for major public health impact
  • Might cause public panic and social disruption
57
Q

Is Y. Pestis easy to grow?

A

Yes, only takes two days

My Packs: (UWO) (MICROIMM 2500) (30 decks)

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