Plague, Tularemia, Brucellosis

Question 1

what is the cause of plague?

Answer 1

Yersinia pestis (Y. pestis)

Question 2

shape and gram stain of Y. pestis?

Answer 2

• large rod-shaped or coccobacillus

- gram negative

Question 3

Y. pestis metabolism

Answer 3

• aerobe or facultative aerobe

- non-lactose fermenter

Question 4

how is Y. pestis transmitted?

Answer 4

1 - flea to mammal (bubonic). Flea regurgitates in bite site, organisms enter lympathics and cause regional adenitis (bubo).
2 - mammal to mammal (pneumonic). respiratory droplets.

Question 5

urban vs. rural plague

Answer 5

urban was through rats and accounted for major human outbreaks. rural is sporadic and in developing countries mostly. caused by flea bite, contact with indigenous rodent, or domestic pet.

Question 6

Y. pestis extracellular pathogens

Answer 6

• anti-phagocytic capsule (F1)
• V and W antigens for survival in macrophage
• anti-phagocytic properties dependent on human 37C temperature

Question 7

Y. pestis intracellular properties

Answer 7

• persistence within mammalian monocytes

Question 8

Y. pestis toxins

Answer 8

• LPS endotoxin

- exotoxin

Question 9

clinical features of bubonic plague

Answer 9

• fever
• malaise
• painful lymphadenopathy

Question 10

clinical features of pneumonic plague

Answer 10

• fever
• cough
• shortness of breath

Question 11

clinical features of septicemic plague

Answer 11

• no bubo

- dissemination via blood

Question 12

plague complications

Answer 12

• DIC
• skin hemorrhages (black death)
• meningitis

Question 13

plague immunity?

Answer 13

• antibodies develop over time

- military vaccine used in Vietnam against bubonic plague

Question 14

plague diagnosis

Answer 14

• bubo aspirate: gram and culture positive confirmed by fluorescent antibody microscopy
• blood culture: positive
• serology: rise in antibody to F1 capsule with hemagglutination test

Question 15

plague treatment

Answer 15

• 10 days streptomycin or tetracycline or chloramphenicol

Question 16

what causes Tularemia?

Answer 16

F. tularensis

Question 17

shape and grain stain of F. tularensis

Answer 17

small unencapsulated pleomorphic gram negative

Question 18

metabolism of F. tularensis

Answer 18

• aerobic slow grower

- requires cysteine, glucose or thioglycolate

Question 19

F. tularensis infectious dose?

Answer 19

5-10 organisms

Question 20

F. tularensis routes of human infection

Answer 20

• rabbit: contact
• arthropod: ticks, deer flies
• infected tissues, animal bite, etc.

Question 21

F. tularensis pathogenesis

Answer 21

• tick bite
• skin lesion
• enter lymphatics, local lymphadenopathy
• bacteremia follows, granuloma formation (spleen and liver)
• intracellular survival in monocytes
• endotoxin has role in symptoms

Question 22

F. tularensis clinical features

Answer 22

• similar to plague
• abrupt onset fever, chills, malaise
• syndromes (see other card)

Question 23

F. tularensis specific syndromes

Answer 23

• ulceroglandular: most common, skin ulcer and painful adenopathy
• typhoidal (bacteremia)
• pneumonia

Question 24

F. tularensis diagnosis

Answer 24

• fluorescent antibody staining of node biopsy

- serologic: 4X titer increase or single titer greater than 1:160 at 2 weeks

Question 25

F. tularensis treatment

Answer 25

- either streptomycin 7-10 days or tetracycline 14 days

Question 26

Brucella gram stain and morphology

Answer 26

- pleomorphic | - gram negative

Question 27

brucella metabolism

Answer 27

- slow grower | - requires CO2 for optimal growth

Question 28

Brucella species

Answer 28

- B. abortus (cattle), milk or meat - B. suis (swine), meat, airborne, slaughterhouse - B. melitensis (goat, sheep), milk, cheese - B. canis (dog), urine

Question 29

brucella pathogenesis

Answer 29

- infectious abortion in huffed animals - infects reticuloendothelial system in humans - neutrophils - multiply in monocytes - granulomas in liver, kidney, spleen, bone marrow

Question 30

brucella clinical features

Answer 30

- systemic and non-focal (FUO) - fever, chills, myalgias, headache, arthralgias - intracellular survival prolongs initial symptoms

Question 31

brucella complications

Answer 31

- osteomyelitis | - endocarditis

Question 32

brucella diagnosis

Answer 32

- occupational history - blood culture - serologic: 4X titer increase - bone marrow biopsy in difficult FUO cases

Question 33

brucella treatment

Answer 33

doxycycline and rifampin for 6 weeks

Question 34

prevention of brucella

Answer 34

- vaccination of calves - herd testing - physical barriers