Micro - Zoonoses (Yersinia pestis, Brucella, Coxiella burnetti) Flashcards
How does Yersinia pestis look on gram stain?
Safety pin appearance; G- bacilli
Two forms of plague:
- Bubonic (lymph nodes)
2. Pneumonia (primary and secondary)
Only zoonose that can be transmitted human-to-human?
Primary plague pneumonia (inhalation)
How is bubonic plague transmitted?
Flea (that bites rodent = reservoir)
How is secondary plague transmitted?
Bubonic plague becomes septic, leading to pneumonia
How can you distinguish if pt has primary or secondary plague pneumonia?
If septic (+ hx of flea bite) = secondary If not septic (- hx of flea bite) = primary
What should you absolutely not treat plague with? Why?
B-lactam or macrolide - YP is resistant to these
What do you treat plague with?
Gentamicin + doxy
If someone has plague, what two things must be done?
- Isolate pt
2. Give doxy for 7 days to anyone exposed
Region affected by plague
New Mexico, SW US
Sx of bubonic plague
Swollen, painful lymph nodes especially in inguinal area (buboes = groin); ulcer at infection site; vomiting
How do you distinguish bubonic plague from tularemia?
Tularemia will have more prominent ulcer at infection site (so would anthrax)
Sx of septic plague
Rapid progression, petechiae, extreme DIC, vomiting and diarrhea, multiorgan system failure
Sx of pneumonic plague
WATERY/BLOODY SPUTUM (not really purulent)
Fever
Rapid progression
Virulence factors of Yersinia pestis
- Type three secretions (like Chlamydia) - paralyze phagocytes
- Fraction 1 (F1) - capsule antigen
How to dx Yersinia pestis
- Culture
- Rapid antigen test for F1
- RADT - urine dipstick for YP
- Gram stain - chubby safety pins
Basis for serological testing of Yersinia pestis?
Abs to F1 antigen
What media does YP grow on and why?
BAP and enteric media - it’s an enterobacteriacae
How is primary plague transmitted?
Humans
Cats
Bioterrorism
Plague doesn’t respond to:
B-lactams or macrolides!!
Which form of plague is contagious?
Primary plague pneumonia
only zoonose transmitted by humans!!
Reservoir for Brucella
Pigs, cows, goats, sheep
How is Brucella transmitted?
Direct contact with infected animal or through UNPASTEURIZED CHEESE
Virulence factors of Brucella
Obligate intracellular parasite of RES (bone marrow, liver, spleen); spreads via lymphatics
Brucella is (G+, G-) (aerobic, anaerobic) (shape)
G- aerobic coccobacillus
Which presentation should make you think of Brucella infection?
Chronic, remitting fever with night sweats in immigrant from Mexico or Mediterranean (bad milk there) or farm/vet/slaughterhouse worker
Sx of Brucella
- Undulant fever = chronic, remitting fever with night sweats
- Long-term sequelae of endocarditis and hepatitis
- Localized infx in lower vertebra, liver, heart
- Can have an acute presentation with high fever and flu-like sx
Characteristic lesion of Brucella
Granulomas in liver, bone
Brucella often confused with:
TB
Tx of Brucella
Long-term Abx
Control via pasteurization, vaccination of cattle, destruction of infected herds
Coxiella burnetti is (G+, G-) (shape)
G- bacillus
Virulence factors of Coxiella
Obligate intracellular parasite Replicates is phagolysosome Endospore form (distributes several miles in wind)
Sx of Q fever
Acute febrile illness
Atypical pneumonia when in spore form
Long-term sequelae of Q fever
Granulomatous hepatitis, endocarditis
Presentation of Q fever
Acute fever in someone who handles animal viscera, drank raw milk, tick bite
Tx of Q fever
Mostly spontaneously resolves
Can give doxy
