MMI 301: Lecture 17: Salmonella/Yersinia

  1. What leads to high prevalence of Salmonella in chicken?
    Crowded conditions of chicken farms
  2. Samonella infection associated with:
    Raw eggs/chickens, pet reptiles
  3. Who isolated Salmonella
    • D.E. Salmon/Theobald Smith
    • Also made first vaccine
  4. Salmonella responsible for what in pigs
    Swine Paratyphoid (Salmonella enterica serotype Choleraesius)
  5. Salmonella Morphology
    Gram - bacillus
  6. Salmonella and Oxygen
    Facultative anaerobe
  7. Salmonella fermentation
  8. Salmonella Motility
    Most strains are, some express phase-switching between two types of flagella gene alleles
  9. Salmonella produces what gas
  10. Salmonella is resistant to:
    Bile acid
  11. Flagellin phase variation induced by:
    Hin recombinase
  12. Flagellin phase switch genes
    • FljB (flagellin gene), FljA (repressor), FljC (flagellin gene)
    • DNA segment contains promotor for FljB
    • In conformation 1). FljB/A are transcribed=B
    • In conformation 2). FljC transcribed=C
  13. Salmonella species
    bongori and enterica (has many subspecies)
  14. Gene's acquired in evolution to virulent Salmonella
    • 1. Invasins, pathogenicity island SPM, differences in LPS genes
    • 2. 2nd T3 S S, SPI2, 2nd set fimbrial genes
    • 3. Hin system, fljBA, std fimbriae
    • 4. sinR transcriptional regulator, rfb cluster (LPS), stc fimbriae
    • 5. stj fimbriae, prophages, 144 genes
  15. Salmonella species that causes human disease
    enterica (2000+ subspecies)
  16. Location of Salmonella
    Most serotypes found in gut, few subspecies are specifically host adapted and cause invasive disease
  17. Serotype names reflect
    Where they were isolated
  18. Salmonella causes:
    Acute gastroenteritis, enteric fever
  19. Acute Gastroenteritis
    Characterized by malaise, abdominal pain, fever, diarrhea. 8-48 after ingesting Salmonella. Usually self-limiting in adults, can be harmful to children/elderly
  20. Enteric fever caused by which serotypes
    Typhi and Paratyphi
  21. Enteric Fever:
    Ileal mucosa invaded and bacteria are picked up by mesenteric tymph nodes, spread to liver, spleen, gall bladder, and bone marrow over 7-10 days. Two weeks later severe endotoxic shock from bacteremia (Kills 20%)
  22. Typhoid fever is:
    Enteric fever caused by Typhi serotype
  23. Cellular uptake of salmonella is mediated by
    Type III system
  24. Type III system uptake
    Type III system injects salmonella-secreted invasion proteins (Sips) into M cells. Causes actin-rearrangement and engulfment.
  25. Yersinia initially enter what kind of cell
    M intestinal cells
  26. Salmonella Epidemiology
    • Source of infection is human waste
    • Control depends on hygiene
    • Identification of healthy carriers and removal of pathogen with antibiotics/cholecystectomy (gall bladder removal)
  27. How many cases of Typhoid fever a year?
    25 Million
  28. Typhoid Mary
    • Mary Mallon
    • Carrier of Typhoid
    • 3 deaths/50 cases
    • Quarantined for 50 years
    • 1904
  29. Gastroenteritis Epidemiology
    • Complex and differs from community to community
    • Most common source is carcasses/products of infected domestic animals
    • Rat/mouse feces can infect food
    • Human waste also
    • Fly-vector
  30. Yersinia species
    pestis, pseudotuberculosis, enterocolitica
  31. Discovery of plague virus
    Alexandre Yersin and Kitasato Shibasaburo discovered in 1894 (Pasteurella pestis to begin)
  32. Cause of bubonic plague
    Yersinia pestis
  33. Yersinia Morphology
    • Gram negative bacillus
    • When stained with Wright/Giesma granules at end will stain purple (resemble a safety pin)
  34. Yersinia and Oxygen
    Facultative anaerobe
  35. Yersinia fermentation
    • Slow lactose fermenter
    • Pestis is not a fermenter
  36. Yersinia can grow at what temp
  37. Forms of plague:
    Bubonic, Urban, Sylvatic, and Pneumonic
  38. Disease caused by Yersinia enterocolitica
    enterocolitis, mesenteric lymphadenitis (aka psuedoappendicitis) and polyarthritic syndrome
  39. Disease caused by Yersinia pseudotuberculosis
    • Mesenteric lymphadenitis w/ necrotic lesions and granulomatous lesions in lymph
    • nodes,   spleen, and liver.
  40. Infection of enterocolitica and pseudotuberculosis
    • Acquired orally, from contaminated food/water
    • Ability to grow at low temp permits enrichment with high numbers of organisms
  41. All three Yersinia share many
    • Virulence factors:
    • Type III (critical)
  42. Specific Yersinia virulence factors
    YOPs, Invasins, Plasminogen activator, Yersiniabactin
  43. YOPs (Yersinia Outer Membrane Proteins)
    • Multiple proteins:
    • Are delivered onto and into host target cells by Type III
    • Have different anti-phagocytic/toxic effects
    • Share similar AA sequence with host regulatory proteins such as tyrosine kinases
  44. Invasins (Yersinia)
    Two enteric pathogenic species capable of cellular invasion due to this outer membrane protein
  45. Plasminogen activator (Pla) (Yersinia)
    granulomatous lesions in lymph nodes,   spleen, and liver.
    protease that converts host plasminogen into plasmin while degrading plasmin inhibitor antiplasmin, freeing from fibrin clots. Crucial in pneumonic plague (works just like Staphylkinase)
  46. Yersiniabactin (Yersinia)
  47. How did Black Death get to europe?
    China from silk traders
  48. Interactions between pestis and fleas
    • 2 days after blood meal, pestis appear in flea stomach
    • 3-9 days pestis moves up into proventriculus (between stomach and esophagus)
    • Next feeding attempt pestis is regurgitated
  49. Plague Life Cycle
    • Zoonotic disease from rodents
    • Transfer from rodent to human by flea
    • Carnivores are resistant
    • Cats are susceptiple (cat to human in pneumonic)
    • Prairie dogs and ground hogs carry in US
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MMI 301: Lecture 17: Salmonella/Yersinia
MMI 301