Yersinia, Francisella, Brucella, And Pasteurella Flashcards
How is Y.pestis transmitted?
- Flea bite
- Contact with infected animal tissue
- Inhaled aerosolized organisms - human to human transmission occurs during epidemics.
Where is Y.pestis found?
- Wild rodents
- City rats
- Squirrels and prairie dogs in the SW U.S.
What is the metabolism of Y.pestis?
- Facultative anaerobe
- Virulence factors are temperature sensitive: only expressed at 37C (inside the macrophages).
- Virulence is plasmid mediated.
What is the virulence of Y.pestis?
- Fraction 1 (F1): this capsular antigen is antiphagocytic.
- V and W proteins
- Non motile
- Requires Ca at 37C.
What are the toxins of Y.pestis?
- Pesticin - kills other bacteria including E.coli.
2. Intracellular murine toxin - lethal to mice.
What can Y.pestis cause?
- Bubonic plague
- Sepsis
- Pneumonic plague
What happens in bubonic plague?
- Regional lymph nodes (groin) swell, become red, hot, and tender.
- High fever
- Conjunctivitis
What happens in pneumonic plague?
During epidemics, pneumonia occurs, as bacteria are spread from person to person by aerosolized respiratory secretions.
100% fatal if untreated.
How can we diagnose Y.pestis?
- Gram (-) rods with bipolar staining.
- Blood culture
- Culture of bubo aspirate
- Serology
- Rapid diagnostic test: antibody against F1 (capsular antigen).
What is useful to keep in mind about Y.pestis?
- Facultative intracellular parasite
- Can accept plasmids from E.coli, and shares many antigens with enteric bacteria.
- Subcutaneous hemorrhage results in a blackish skin discoloration. (Black Death).
Where is Y.enterocolitica found?
Wild and domestic animals.
How is Y.enterocolitica transmitted?
Via unpasteurized milk.
What is the metabolism of Y.enterocolitica?
- Facultative anaerobe
2. Temperature sensitive virulence factors - only at 37C expressed
What is the virulence of Y.enterocolitica?
- Invasive
- V & W proteins
- Motile at 25C
What are the toxins of Y.enterocolitica?
Enterotoxin (like ST toxin of E.coli): increase cGMP levels.
What can Y.enterocolitica cause?
- Enterocolitis
- Arthritis
- Rash
How can we diagnose Y.enterocolitica?
Cold enrichment of stool with saline selects for Yersinia.