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MHD Block 3: Zoonosis > Yersinia Pestis > Flashcards

Yersinia Pestis Flashcards

1
Q

What did Yersinia Pestis cause?

A

PLAGUE

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2
Q

How was the plague transmitted?

A

Flea bite
Direct contact wiht infected tissues
Inhalation of infected aerosols from pt with pulmonary disease

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3
Q

Is Y.Pestis infections still present?

A

YES.

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4
Q

What are the 2 epidemic forms of Yersinia Pestis?

A

Urban Plague: Plague maintained by rat population and spread to humans via fleas

Sylvatic Plague: Endemic in Western US and carried by prairie dogs, mice, rats, rabbits

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5
Q

Describe the pathogenesis of plague

A

Organisms multiply in flea’s gut -> flea bites human/rodent -> organism move from bite site to lymph nodes-> multiply in lymph nodes-> necrosis + swelling -> BUBO -> disseminate to blood, lungs, liver and spleen

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6
Q

Describe the pathologic characteristics of plague

A

Facultative Intracellular Organisms
Resist killing and multiplies in mononuclear phagocytes
Multiplies freely in EC evironment

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7
Q

What is pneumonic disese from Y.Pestis characterized by?

A

Hemorrhagic pneumonia

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8
Q

What is characteristic of “Black Death”

A

Terminal Cyanosis (fingers)

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9
Q

What is the clinical presentation of the Bubonic Plauge?

A

Fever and painful bubo 2-7 days after bite
Sudden onset of fever chills, weakness, HA
Intense pain in region with buboes
75% mortality if untreated

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10
Q

What is the clinical presentaiton of Septicemic Plague

A

Direct infection of blood by flea bite
High fever, delirium, seizures in kids, septic shock, DIC
Black Hemorrhagic splotches

High fatality rates due to delay in Dx and Tx

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11
Q

How does pneumonic plague arise?

A

Hematogenous spread of plague bacillus to lungs
OR
Inhalation of infectious aerosol from pt with plague

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12
Q

What is the clinical presentation of a pt with pneumonic plague?

A

Initial: HA, malaise, fever, vomiting, confusion, prostration
Later: Cough, chest pain, Hemoptysis
Eventually to sepsis and death unless treated within 1 day after onset of sx

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13
Q

What category does Y.Pestis fall into?

A

Category A Bioterrorism Agent

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14
Q

What is the DDx when a pt is suspected to have plague?

A

REye’s Syndrome
Tularemia
Bacterial Pneumonia
Acute Surgical Abdomen

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15
Q

What should you suspect plague based on a pt’s history?

A

Febrile pts who have been exposed to rodents or mammales in known epidemic areas

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16
Q

How can a bacteriologic diagnosis of the plague be done?

A

Smear and culture of bubo aspirate, blood, or sputum sample
Must notify lab of possible pestis

Shows Inc WBC and normal or low plateletcount with DIC

17
Q

What are the key identifying features of Y.Pestis?

A 
Oxidase Neg
Non-Motile
Enterobacteriaceae
Bipolar Gram - Stain - coccobacilli (safety pin)
Glucose Fermenter
Slow growing colonies look like fried egg or beaten copper
Small pinpoint colonies on MacConkey
Faster growth at 28C than 37C
18
Q

How is Y.Pestis treated?

A

Streptomycin

Alternatives: Gentamicin, Chloramphenicol, Tetracyclines

19
Q

Which abx are NOT effective intreating Y.Pestis?

A

Penicillin

Cephalosporin

20
Q

WHat is given for chemoprophylaxis for Y.Pestis?

A

Tetracycline

21
Q 
• A 6 Y.O. boy arrives with his mother in ER complaining of pain in right arm where a cat had bit him the previous day. The next morning the boy awoke crying and complaining of pain in his hand. Temp 39 C. Skin over the wound is erythematous. Material from the wound is submitted for culture and Gram stain. The laboratory reports growth of gram-negative coccobacilli. The organisms were faculatatively anaerobic but failed to grow on MacConkey agar. Which organisms is most likely responsible for this
infection?
A. Capnocytophaga
B. Eikenella
C. Escherichia
D. Fusobacterium
E. Pasteurella
6
A

E

22
Q 
Which arthropod is the most important vector of
tuleremia?
A. House fly
B. Flea
C. Lice
D. Tsetse fly
E. Tick
A

E

23
Q

During a military conflict in Somalia, several soldiers develop a febrile illness characterized by abrupt onset of fever with rigors, severe headaches, myalgias, arthralgias, lethargy, photophobia, and coughing. Conjunctival suffusion and a petechial rash develop 4 days into the illness and then fade after 1 to 2 days at the time symptoms wane. Splenomegally and hepatomegaly are also observed. After 1 week, the symptoms recur. Blood cultures are collected during febrile
phase and are positive after extended (7 days) incubation with small, faint staining gram-negative coccobacill. What is the likely etiologic agent for this disease?
A. Brucella melitensis
B. Escherichia coli
C. Francisella tularensis
D. Haemophilus influenzae
E. Pasteurella multocida

A

a

MHD Block 3: Zoonosis (4 decks)

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