Plague, Tularemia, Brucellosis

Question 0

T/F: Yersinia Pestis is anaerobic

Answer 0

False - Y. Pesitis is a facultative AEROBE

Question 1

Yersinia Pestis is a large/small ___-shaped GM _______

Answer 1

Large rod shaped (coccobacillus) Gram NEGATIVE

Question 2

T/F: Yersinia pestis can ferment lactose

Answer 2

False, it does not ferment lactose

Question 3

Yersinia Pestis is the cause of ______ and belongs to the family _________________

Answer 3

Causes plague (bubonic, pneumonic) and is of the family ENTEROBACTERICEAE

Question 4

Bubonic transmission of Y pestis in 4 basic steps:

Answer 4

Bubonic = flea to mammal

1. Flea gets Y. pestis after blood meal
2. Y. pestis multiplies in/obstructs foregut
3. Obstructed flea tries to feed; regurgitates 24000 organisms into bite site
4. Organisms enter lymphatics, causing regional adenitis in mammal

Question 5

Primary Pneumonic transmission of Y. pestis (2 steps):

Answer 5

(mammal to mammal)

1. Bubonic plague -> secondary pneumonia
2. Spread via resp. droplets -> primary pneumonia in contacts

Question 6

Most current cases of plague in the US are acquired via (3):

Answer 6

1. flea bite
2. hand contact with infected animal
3. contact w/ domestic pets

(about 10 cases per year of rural plague - often southwest US)

Question 7

What is the F1 Antigen

Answer 7

The ANTIPHAGOCYTIC CAPSULE of Y. Pestis that is required for virulence

Question 8

What are the V and W antigens?

Answer 8

These enable Y. pestis to survive inside macrophages.

Question 9

How does the antiphagocytic property of Y. Pestis vary?

Answer 9

The antiphagocytic property is present at 37 C (mammal temp) but not at 28 C (flea temp)

Question 10

What is/are the toxin(s) of Y. pestis?

Answer 10

Classic LPS endotoxin

Exotoxin

Question 11

Clinical Features of:
Bubonic plague -
Pneumonic plague -
Septicemia plague -

Answer 11

Bubonic - fever, malaise, and painful lymphadenopathy
Pneumonic - fever, cough, SOB
Septicemic - no bubo, dissemination via blood

Question 12

Complications of plague: (2)

Answer 12

DIC -> skin hemorrhages (black death)

Plague meningitis

Question 13

Immunity to plague??

Answer 13

1. Antibody is developed after infection and is proctective

2. Inactivated vaccine exists that protects from bubonic (used by Vietnam troops)

Question 14

Methods to diagnose plague: (3)

Answer 14

1. Bubo aspirate - Gm stain + culture positive
2. Blood culture
3. Serology - 4x rise in Ab to F1 capsule is diagnostic

Question 15

Your patient has the plague! What is the treatment? What is the chance they might die?

Answer 15

10 days tetracycline, or streptomycin, or chloramphenicol.

60-90% mortality if UNTREATED
5% if started antibiotics early

15 % overall US mortality

Question 16

T/F: Franciscella tularensis is a small encapsulated pleomorphic gram negative

Answer 16

False;

Franciscella tularensis is a small UNENCAPSULATED pleomorphic GM negative

Question 17

Franciscella tularensis is an aerobic slow growing culture; what two metabolites are required for its growth?

Answer 17

CYSTEINE and glucose

Question 18

T/F: F. Tularensis can survive in water for up to 90 days

Answer 18

True; it is COLD TOLERANT

Question 19

approximate infectious does of F. Tularensis?

Answer 19

5-10 organisms

Question 20

Routes of human infection by Franciscella tularensis: (3)

Answer 20

1. Rabbit - hand contact or ingestion ( winter disease in east US)
2. Arthropod borne - ticks, deer flies (summer disease in west)
3. Other - handling infected tissue, animal bites, laboratory aerosol, shaking dog

Question 21

After a tick bite injection of F. tularensis organisms, they will:

Answer 21

1. Cause skin lesion
2. Enter lymphatics - > lymphadenopathy
3. Produce bacteremia -> granuloma formation in reticuloendothelial system (Spleen, liver)
4. Survive intracellularly in monocytes
   (endotoxin will play a role in initial symptoms)

Question 22

F. Tularensis infection causes a sudden onset fever, malaise, and chills - what are the specific syndromes it may cause?

Answer 22

1. Ulceroglandular: most common, skin ulcer and painful adenopathy
2. Other: typhoidal bacteremia, pneumonia

Question 23

What is a complication of F. Tularensis infection?

Answer 23

Pneumonia (10-15%)

mortality <1% with antibiotics

Question 24

Treatment for Franciscella tularensis infection

Answer 24

streptomycin (bacteriocidal) for 7-10 days

Relapse may occur due to intracellular persistence

Question 25

T/F: There is a Live attenuated vaccine available for Franciscella tularensis

Answer 25

True

Question 26

Brucella is a ________ (morphology) gram ________

Answer 26

Pleomorphic gram negative

Question 27

Brucella grows (fast/slow) and requires ______ for growth

Answer 27

slow, requires CO2

Question 28

Brucellosis is common in developing countries due to:

Answer 28

Transmission from unpasturized milk/cheese or direct cattle contact

Question 29

What does brucellosis do to
Cows?
Humans?

Answer 29

Cows - abortion (localization to placenta) (sheep, pig, goat too)
Human - reticuloendothelial disease (spleen, liver)
-> organisms ingested by PMNs multiply then form granulomas in liver kidney spleen and marrow

Question 30

Clinical features of brucella infection

Answer 30

Systemic non-focal fever, chills, myalgias, HA, arthralgias
prolonged initial symptos due to IC persistance
Complications: osteomyelitis (vertebral) and endocarditis

Question 31

Brucella diagnosis:

Answer 31

Occupational hx
21 day blood culture
4x titer increase (will cross react with tularemia, typhoid, cholea vacc, brucella skin test)
marrow biopsy

Question 32

Treatment for brucellosis

Answer 32

Doxy + Rifampin for 6 weeks
25% relapse
1-2% mortality