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Flashcards

Microbes & Disease - Lecture 9

Afronewtzz Microbes & Disease Degree English 64 cards

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  1. 1What is the respiratory tract?Extends from the nose to the alveoli.
  2. 2List 4 different Urinary Tract Infections...- Otitis media
    - Tonsillities
    - Laryngitis
    - Ear infections
  3. 3List 5 different Lower Respiratory Tract infections...- Bronchitis
    - Bronchiolitis
    - Pneumonia
    - Whooping cough
    - Tuberculosis
  4. 4What are 2 respiratory pathogens which cause lung infections?Bordetella pertussis
    Mycobacterium tuberculosis
  5. 5What is the morphology of Bordetella pertussis?- Gram -ve
    - Very small coccobacillus
    - Single or in pairs
  6. 6What type of metabolism does Bordetella pertussis have?Aerobic
  7. 7How does Bordetella pertussis grow on rich blood agar?Very slowly
  8. 8What other media can Bordetella pertussis be grown on? What is commonly added to growth media?Synthetic medium containing amino acid energy source and growth factors.
    Charcoal - Neutralises the highly toxic biproducts produced which would otherwise kill the bacteria.
  9. 9How many serotypes of Bordetella pertussis are there that are pathogenic to humans? What are they called?3
    - Type 1,2
    - Type 1,3
    - Type 1,2,3
  10. 10How many agglutinogens are produced by Bordetella pertussis when grown in blood serum?3
  11. 11Why is tracing of infection by Bordetella pertussis' serotypes virtually impossible?Because of the spontaneous reversible variation (1,2 <> 1,2,3 <> 1,3)
  12. 12What mechanism is currently used to trace epidemic spread of Bordetella pertussis?Pulse-field gel electrophoresis (PFGE). This involves analysis of macrorestriction digests (by restriction enzymes) of genomic DNA. This traces whether a microorganism is of a particular strain.
  13. 13Are humans the only known host for Bordetella pertussis?Yes.
  14. 14What does Bordetella pertussis colonise in the human body?Cilia of human respiratory epithelium.
  15. 15Bordetella pertussis are thought to not invade host cells, however, what cells are they found in?Alveolar macrophages
  16. 16How is Bordetella pertussis transmitted between people and is it infectious?Via inhalation of aerosols... and HIGHLY infectious!
  17. 17What is a relatively mild disease in adults but shows significant mortality in infants (caused by Bordetella pertussis)?Whooping cough
  18. 18When was a vaccine for Whooping Cough introduced (before which, it was a frequent and severe disease of infants)?1930s
  19. 19Do Bordetella pertussis in whooping cough bind to any other cells than the ciliated cells in the respiratory tract?No.
  20. 20What is the length of incubation period for Whooping Cough?7-10 days.
  21. 21What symptoms show in the 'Catarrhal' stage of infection by Bordetella pertussis? (5). How long does this stage last?- Rhinorrhea (runny nose)
    - Malaise
    - Fever
    - Sneezing
    - Anorexia
    1-2 weeks.
  22. 22What symptoms show in the 'Paraoxysmal' stage of infection by Bordetella pertussis? (3). How long does this stage last?- Repetitive cough with whoops
    - Vomiting
    - Lekocytosis
    2-4 weeks.
  23. 23What symptoms show in the 'Convalescent' stage of infection by Bordetella pertussis? (2). How long does this stage last?- Diminished paroxysmal cough
    - Development of secondary complications (pneumonia, seizures, encephalopathy).
    3-4 weeks or longer.
  24. 24What are the 2 main stages of infection by B. pertussis?Colonisation
    Toxemic stage.
  25. 25During the colonisation of the respiratory tract of B. pertussis, what symptoms are shown?- Fever, malaise and coughing which increase in intensity over a 10-day period.
  26. 26Can the microorganism B. pertussis be recovered and controlled by antimicrobial treatment during the colonisation stage?Yes.
  27. 27What is characteristic of the B. pertussis during the toxemic stage of disease?- Building up of prolonged and paroxysmal coughing.
  28. 28Can B. pertussis be recovered and controlled by antimicrobial agents during the toxemic stage of infection? What other methods can be used?No. Steroid and fluid replacement therapy can be used to manage symptoms.
  29. 29What are the 2 most important colonisation factors for B. pertussis?- Filamentous haemogglutinin / FHA
    - Pertussis toxin/ PT/ PTx
  30. 30Briefly describe FHA/ Filamentous Haemogglutinin.- Colonisation factor for B. pertussis
    - Forms filamentous structure
    - Binds to galactose on glycolipid sulfatide on ciliated cells.
  31. 31Is there an immune response to FHA colonisation factor of B. pertussis?Yes, we produce antibodies to this.
  32. 32Briefly describe the invasive adenylate cyclase toxin of B. pertussis.- Cell-associated or released
    - Enters mammalian cells
    - Reduces phagocytic activity
    - Haemolysin (lyses RBCs)
  33. 33What is the end result of Haemolysin on Blood agar?Hemolytic/ clear zone
  34. 34What is the purpose of the Lethal Toxin produced by B. pertussis?Inflammation & local necrosis
  35. 35What is the sole purpose of the Tracheal Cytotoxin released by B. pertussis?- Toxic for ciliated cells > stops ciliary beat > cytotoxic
    - Stimulates release of cytokine IL-1, causing fever.
  36. 36Describe the structure of the Pertussis Toxin of B. pertussis.- AB-type toxin
    - A subunit: Composed of S1 - enzymatically active with ADP ribosyl transferase.
    - B subunit: Composed of S2 - S5 and is the receptor binding subunit.
    - S2 = Lactosylceramide receptor on the ciliated cells.
    - S3 = Glycoprotein receptor on phagocytic cells.
  37. 37Aside from using S3 on the B subunit of Pertussin toxin, how else does B. pertussis bind phagocytic cells?Uses FHA colonisation factor via integrin CR3.
    Together with PTx, phagocytic entry is gained.
  38. 38How do B. pertussis reside inside phagocytes without getting killed?- Resist killing by release of other toxins such as adenylate cyclase toxin.
    - Thus, an intracellular parasite.
  39. 39In what year was a whole-cell pertussis vaccine developed?1930
  40. 40What was the DTP vaccine (introduced in mid-1940s) like?- Inactivated, whole bacterial cells & toxoid of Petussis in formalin...
    - Inclusion with Diphtheria & Tetanus toxoids
  41. 41What was the DTaP vaccine (introduced in 1991) like?- Similar to DTP but...
    - Pertussis component is purified 'acellular' version >> fewer side effects.
  42. 42What is the Tdap vaccine (introduced in 2005) like?Tetanus toxoid- diphetheria- acellular pertussis.
  43. 43What are the 3 Mycobacteria Human Pathogens? Which is uncommon? Which is common in the immunocompromised?- Mycobacterium tuberculosis
    - Mycobacterium leprae - uncommon.
    - Mycobacterium avium- intracellulare complex / MAC/ M. avium - Immunocompromised.
  44. 44What disease is caused by Mycobacterium tuberculosis?/ MTBTuberculosis
    Granuloma production
  45. 45What type of metabolite is Mycobacterium tuberculosis?Obligate aerobe
  46. 46Is Tuberculosis chronic?Yes
  47. 47Describe the morphology of Mycobacterium tuberculosis.- Gram +ve
    - Bacilli
    - Non-motile
    - Rods
    - Non-sporulating
    - Non-capsulate
  48. 48What is the limited temp. range for growth of Mycobacterium tuberculosis? What is the optimum growth temp.?25 to 41 degrees celsius.
    35 to 37 degrees celsius.
  49. 49How does M.TB appear in clinical samples/ sputum?- Single cells
    - Small clumps
  50. 50How does M. TB grow in liquid culture?- Twisted rope-like micro-colonies called Serpentine cords.
  51. 51What can be reflected by M.TB's compact, often wrinkled colonies, on agar?- High lipid content of cell envelope.
    - Hydrophobic cell surface (shrivel away)
  52. 52What stimulates the growth of M. TB?- Lipids/ fatty acids e.g. egg yolk.
  53. 53What is the most widely used medium for growing M. TB? What is this medium composed of?- Lowenstein Jensen Medium/ LJ
    - Whole egg based
    - Contains malchite green, glycerol, asparagine etc.
  54. 54When is M. TB growth normally visible on LJ medium?2 - 8 weeks
  55. 55Why does the Gram +ve cell wall structure of Mycobacterium not stain very well? How is this overcome?- Due to mycolic acids
    - Lipids removed with alkaline-alcohol...
    - Can now be Gram stained.
    - Therefore, the usual stain is...
    - Acid-fast
    - Basic fuchsin & phenol (solvent) is used in acid- alcohol with heat.
  56. 56What is essential in order M. TB to be pathogenic?Cord Factor
  57. 57Are both healthy and immunocompromised people susceptible to TB?Yes
  58. 58Why is TB a serious infectious disease?Global problem - endemic in many countries
  59. 59Where does TB primarily infect?Lung
  60. 60Describe the primary infectious stage of M. tuberculosis.- M. TB engulfed by alveolar macrophages
    - Bacteria multiply within these macrophages.
    - Macrophages & ingested bacteria travel to local lymph nodes.
    - Cell mediated immunity > restrains the spread.
    - T cells are sensitized and lymphokines are produced.
    - Body tries to contain bacteria within 'tubercles'.
    - Tubercles may heal spontaneously...
    - May become fibrotic/ calcified & persist for lifetime.
    - Can cause disseminated disease in immunocompromised.
  61. 61Describe the onset of TB?- Slow progressing initially
    - Infection establishes before patient aware
  62. 62What % of primary TB is often asymptomatic?- 90% of cases
    - In remaining 10%, clinical disease develops.
  63. 63Describe secondary infection with Tuberculosis.- Dormant microbes are reactivated.
    - Usually as a result of impaired immune function (AIDS, chemotherapy for malignancy).
  64. 64What immunoprophylaxis and chemotherapy procedures are in place for TB?- Drug regimens
    - Immunoprophylaxis with BCG vaccine
    - BCG vaccine = Bacille Calmette- Guerin = weakened version of M. bovis.

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Respiratory pathogens - Lung Infections
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Afronewtzz
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