Path Test 4: Infectious Diseases

  1. Enters from outside the body
  2. Already present as part of normal flora
  3. Two dissimilar organisms living in close association
  4. Living on or within, deriving benefit w/o injuring or providing benefit to another organism
  5. Both organisms gain benefit, often cannot survive separately
  6. One derives benefit while the other is harmed in some way
  7. Parasite that lives outside the body
  8. Parasite that lives within the body
  9. Parasite whose entire life cycle occurs in one host
  10. Parasite that requires more than one host
  11. One organism derives no benefit while the other is harmed
  12. Both organisms are harmed
  13. Lack of interaction
  14. Main host or one in which sexual cycle takes place
    Definitive host
  15. Temporary host for larval stages, asexual repro, development
    Intermediate host
  16. Intermediate host actively involved in transmission
  17. Transport host; other than intermediates host that carries parasites to definitive host
    Paratenic host
  18. Alternate definitive host; maintains infxn
    Reservoir host
  19. Alternative definitive host that for some reason is rarely infected, often the life cycle cannot be completed
    Accidental host
  20. GI tract bug:  causes malabsorption by numbers/ blocks epithelial surface
  21. GI tract bug:  Penetrates into mucosa and sucks blood
  22. GI tract bug:  Absorbs large quantities of Vit. B12
    D. latum
  23. GU tract infxn is typically accomplished by
    extension (periurethral bacteria, hematogenous spread, sexual contact)
  24. Properties of potential pathogen that allow it to establish within the host, avoid the host defenses and cause disease
    Virulence Factor
  25. Name 2 adherence factors
    • Pilus
    • Adhesins
  26. Proteins that promote tighter binding of bacteria to host.  Name 2 examples
    • Adhesins
    • M protein= inhibits macrophages ingestion
    • F protein= binds fibronectin
  27. Name 3 toxins
    • Exotoxin
    • Neurotoxin
    • Membrane-disrupting toxin (usually phospholipase)
    • Superantigen
  28. Typically heat labile, secreted into local environement: often A-B type (A has enzyme activity; often disrupts cAMP levels)
  29. Inhibits release of neurotransmitters
  30. Non-specifically bind to a conservatie region of T lymphocyte receptor
  31. Name 5 diseases with superantigens
    • Toxic Shock Syndrome (TSS)
    • RA
    • MS
    • Graves
    • SIDS
  32. Endotoxin
  33. Toxic component of LPS
    Lipid A
  34. Chelates iron, competes with transferrin
  35. Inhibits C3b binding, inhibition of IFN activity, etc.
    Sialic acid residues
  36. Elevated WBC:
    No shift?
    • Left-shift:  bacterial
    • No shift: viral
    • Eosinophilia: parasites
  37. Common tests on dip stick for neutrophils
    Leukocyte esterase (urine test)
  38. Not normally present in urine, but is produced by a # of bacterial species
  39. Meningitis most common bacteria:
    • Neonates:  Grp. B Strep, E. coli
    • Children:  H. influenza, S. pneumo, Neisseria
    • Adults:  S. pneumo, Neisseria
    • Elderly:  Bacillus, S. pneumo, HI, Listeria
    • Post-neurosurgery:  Staph, Pseudomonas
  40. Name 2 stains done to check for CSF bacteria
    • Gram Stain
    • India Ink
  41. Gram stain of male urethal discharge is senesitive/ specific for this, but NOT for females
    Neisseria gonorrhoeae
  42. Obtained from a chancroid, needs special media for culture
    H. ducreyi
  43. 3 types of Urinary tract specimens
    • 1) Clean catch
    • 2)  Suprapubic:  Infants where clean catch was not succesful; suspect anaerobes
    • 3)  Catheter:  Shouldn't be used for culture sample
  44. Only thing you refrigerate (and only if it takes more than 2 hours from collection to culture)
    Urine sample
  45. Feces sample bacteria:  Sensitive to drop in pH secondary to anaerobic metabolism, needs specific media
  46. Feces sample bacteria:  Doesn't survive in buffered glycerol
  47. Catalase Test
    Add H2O2 to culture, if catalase is present, it will bubble
  48. Certain organisms produce diffusible extracellular protein (CAMP factor) that works with beta-lysin of S. aureus to cause hemolysis
    Camp test
  49. Performed to see if certain bacteria will use citrate as their sole carbon source and ammonium as sole nitrogen source
    Citrate utilization test
  50. Allows transport of citrate into bacteria
    Citrase permease
  51. Defense mechanism to clot surrounding plasma and resist phagocytosis.  This enzyme is produced by Staph.
    • Coagulase
    • (Coagulase Test)
  52. Measures ability of microorganism to degrade tryptophan into indole, ammonia, and pyruvic acid.
    Indole test
  53. Degradation of tryptophan is detected through addition of
    Kovack's reagent (reacts w/ indole and makes a red color)
  54. Used to ID strains of strep pneumonia; has detergent-like action and causes selective lysis of pneumococci
    Optochin test (S. pneumonia is optochin sensitive so zone of inhibition will develop around the disk where the bacteria have lysed)
  55. Determines if organism possesses cytochrome c
    Oxidase test

    • Absence of cytochrome c= clear
    • Presence of cytochrome c= purple
Card Set
Path Test 4: Infectious Diseases
Path Test 4 Infectious Diseases