Plague, Tularemia, Brucellosis Flashcards
(33 cards)
T/F: Yersinia Pestis is anaerobic
False - Y. Pesitis is a facultative AEROBE
Yersinia Pestis is a large/small ___-shaped GM _______
Large rod shaped (coccobacillus) Gram NEGATIVE
T/F: Yersinia pestis can ferment lactose
False, it does not ferment lactose
Yersinia Pestis is the cause of ______ and belongs to the family _________________
Causes plague (bubonic, pneumonic) and is of the family ENTEROBACTERICEAE
Bubonic transmission of Y pestis in 4 basic steps:
Bubonic = flea to mammal
- Flea gets Y. pestis after blood meal
- Y. pestis multiplies in/obstructs foregut
- Obstructed flea tries to feed; regurgitates 24000 organisms into bite site
- Organisms enter lymphatics, causing regional adenitis in mammal
Primary Pneumonic transmission of Y. pestis (2 steps):
(mammal to mammal)
- Bubonic plague -> secondary pneumonia
- Spread via resp. droplets -> primary pneumonia in contacts
Most current cases of plague in the US are acquired via (3):
- flea bite
- hand contact with infected animal
- contact w/ domestic pets
(about 10 cases per year of rural plague - often southwest US)
What is the F1 Antigen
The ANTIPHAGOCYTIC CAPSULE of Y. Pestis that is required for virulence
What are the V and W antigens?
These enable Y. pestis to survive inside macrophages.
How does the antiphagocytic property of Y. Pestis vary?
The antiphagocytic property is present at 37 C (mammal temp) but not at 28 C (flea temp)
What is/are the toxin(s) of Y. pestis?
Classic LPS endotoxin
Exotoxin
Clinical Features of:
Bubonic plague -
Pneumonic plague -
Septicemia plague -
Bubonic - fever, malaise, and painful lymphadenopathy
Pneumonic - fever, cough, SOB
Septicemic - no bubo, dissemination via blood
Complications of plague: (2)
DIC -> skin hemorrhages (black death)
Plague meningitis
Immunity to plague??
- Antibody is developed after infection and is proctective
2. Inactivated vaccine exists that protects from bubonic (used by Vietnam troops)
Methods to diagnose plague: (3)
- Bubo aspirate - Gm stain + culture positive
- Blood culture
- Serology - 4x rise in Ab to F1 capsule is diagnostic
Your patient has the plague! What is the treatment? What is the chance they might die?
10 days tetracycline, or streptomycin, or chloramphenicol.
60-90% mortality if UNTREATED
5% if started antibiotics early
15 % overall US mortality
T/F: Franciscella tularensis is a small encapsulated pleomorphic gram negative
False;
Franciscella tularensis is a small UNENCAPSULATED pleomorphic GM negative
Franciscella tularensis is an aerobic slow growing culture; what two metabolites are required for its growth?
CYSTEINE and glucose
T/F: F. Tularensis can survive in water for up to 90 days
True; it is COLD TOLERANT
approximate infectious does of F. Tularensis?
5-10 organisms
Routes of human infection by Franciscella tularensis: (3)
- Rabbit - hand contact or ingestion ( winter disease in east US)
- Arthropod borne - ticks, deer flies (summer disease in west)
- Other - handling infected tissue, animal bites, laboratory aerosol, shaking dog
After a tick bite injection of F. tularensis organisms, they will:
- Cause skin lesion
- Enter lymphatics - > lymphadenopathy
- Produce bacteremia -> granuloma formation in reticuloendothelial system (Spleen, liver)
- Survive intracellularly in monocytes
(endotoxin will play a role in initial symptoms)
F. Tularensis infection causes a sudden onset fever, malaise, and chills - what are the specific syndromes it may cause?
- Ulceroglandular: most common, skin ulcer and painful adenopathy
- Other: typhoidal bacteremia, pneumonia
What is a complication of F. Tularensis infection?
Pneumonia (10-15%)
mortality <1% with antibiotics
