Yersinia Flashcards
Is yersinia pestis common in the intestine?
No
- causes plague
Y. pestis
Gram neg, non-motile, coccobacillus, non-hemolytic, non-lactose fermenting
- does not survive long in environment
- grows slowly at 28 C
Endemic disease in animals
Voles and deer mice (usually do not have serous disease)
Accidental animal hosts
- cattle, horses, swine, and sheep are not susceptible
- wild and domestic cats can acquire infection by ingesting infected rodents
Disease in cats
Bubonic plague is most common
- lymphadenitis
- fatal
- need to isolate cases and report to CDC
Human disease
Bubonic plague is most common
- pneumonic plague: most serious form of disease, the only form of plague that can spread from person to person
- septicemic plague: progression from either bubonic or pneumonic plague
Transmission
- infected flea bites (sylvatic plague), which leads to bubonic plague
- infected cats thru scratches or bites
How is Y. pestis shed?
From infected people/cats thru sputum or respiratory droplets
- directly spread from human to human
Flea transmission
Spread through infected Oriental rat fleas, who feed on rats and rodents
- cat and dog fleas do not transmit Y. pestis efficiently
Virulence factors
- LPS
- capsule (F1)
- type 3 secretion system
- iron acquisition
Pathogenesis
Phagosome-lysosome fusion occurs, but Y. pestis is able to survive in mononuclear cells
- survival in macrophages is by effectors from type 3 secretion system (Yops) to inhibit phagocytosis and proinflammatory cytokine release
- Yops also trigger apoptosis of macrophage
Y. pseudotuberculosis
Enteropathogen of wild and domestic animals
- genetically similar to Y. pestis
- can persist in the environment
Y. pseudotuberculosis disease
Transmitted by fecal-oral route
- acute: blood, mucoid diarrhea, gasteroenteritis, death within 24-48 hrs
- chronic: caseous abcesses in intestinal wall, mesenteric lymph nodes, liver, spleen (similar in tuberculosis)
Who are reservoirs of Y. pseudotuberculosis?
Gregarious wild birds
- blackbirds, grackles, starlings
- rats
Who is the most commonly infected domestic animal?
Cats
- especially adult rural outdoor cats
What is a difference between Y. pseudotuberculosis and Y. pestis?
Disease is usually limited to gastroenteritis
Pathogenesis of Y. pseudotuberculosis
3 adhesins that adhere to luminal surface of M cells and basolateral surfaces of ileal enterocytes
- Ail, Inv, and Yad
- all 3 are outer membrane proteins
- passes thru M cells, afterwards pathogenesis is similar to Y. pestis
- facultative intracellular parasite of macrophages
What causes diarrhea in Y. pseudotuberculosis?
Prostaglandin synthesis from recruited neutrophils
Diagnosis
Culture from feces or lymph node aspirates
- benefited by cold enrichment at 4 C for several weeks
Who are carriers for Y. enterocolitica?
Swine
- one of the major sources of human infection with serobiotype O:3/4 is thru handling of swine and consumption of pork
Y. enterocolitica disease
Gastroenteritis, bloody diarrhea, ileitis, mesenteric adenitis in people and animals, pseudoappendicitis in people
- similar clinical signs to Y. pseudotuberculosis
Pathogenesis of Y. enterocolitica
Invasion through M cells
- initially is an intracellular pathogen in macrophages, then it becomes extracellular
Y. ruckeri
Enteric red-mouth disease of salmon and trout
- transmitted through direct contact or through fomites
- hemorrhagic septicemia: hemorrhages on body surface and around mouth
Who is most susceptible to Y. ruckeri?
Rainbow trout
- bacterin is effective in controlling
