Blood Cultures 7.3

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Blood Cultures 7.3
2010-08-12 22:40:56
Blood Cultures Micro Microbiology NSHS MLT

blood cultures 7.3
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  1. this is the invasion of bloodstream by virulent microorganisms.
  2. this is the transient presence of bacteria or other microorganisms in the blood.
  3. this is the presence of fungi in the blood stream.
  4. this is the presence of viruses in the blood, characterized by malaise, fever, and aching of the back and extremities
  5. septic shock is caused by what?
    the release of toxins
  6. what are five signs and symptoms of spetic shock?
    • fever
    • respiratory distress
    • I.V. coagulation
    • Renal failure
    • tissue damage
  7. this is one of the most important specimens.
    blood culture
  8. healthy individuals have _______ blood.
  9. what is the objective of blood cultures?
    initiate growth of tastidious organisms
  10. this involves very small numbers of organisms.
  11. is septicemia more common in adults or infants?
  12. this may depend on prompt recognition by bacteriologic means.
  13. true or false
    positive blood cultures reflect a variety of conditions and diseases
  14. bacteremia is __________ in endocarditis, concontrolled infections, typhoid fever, and brucellosis.
  15. in the early antibiotic era the primary concern was spesis due to what?
    staphylococcus aureus
  16. recently there is an increase in infections caused by gram negative bacteria such as what?
    • E. Coli
    • Psudomonas
  17. what are the two most frequent isolates from the pediatric population?
    • haemophilus influenzae
    • streptococcus pneumoniae
  18. what is the mortality rate of septicemias?
  19. this is reported in approximately 18% of proven septicemias, and associated with a higher mortality than unimicrobial infection
    polymicrobial bacteremia
  20. what three diseases are significant to gram negative septicemia?
    • acute fulminating meningoccemia (waterhouse friderichsen syndrome)
    • meningococci lipopolysaccharide endotoxin
    • coagulation cascade activation (DIC)
  21. which gram negative septicemia disorder is seen mainly in children under ten years old?
    acute fulminating meningococcemia (waterhouse friderichsen syndrome)
  22. what two broths can be used for blood culture media?
    • BHI
    • TSB
  23. what amount of CO2 is used in blood culture media?
  24. this allows the maximal yield of fastidious organisms and dispaces oxygen for anaerobic conditions.
  25. what is the anticoagulant used in blood culture media?
    sodium polyanethol sulfonate (SPS)
  26. what are three advantages of sodium polyanethol sulfonate as an anticoagulant?
    • antiphagocytic
    • anti-complementary
    • inactivates certain antibiotics (aminoglycosides)
  27. what is the disadvantage of sodium polyanethol sulfonate as an anticoagulant?
    inhibitory for certain bacterial species
  28. what four bacterial species are inhibited by sodium polyanethol sulfonate?
    • peptostreptococcus anaerobius
    • gardnerella vaginalis
    • some neisseria strains
    • S. monliformis
  29. how is the inibitory action of SPS neutralized?
    1.2% gelatin
  30. why is citrate and oxalate not used as an anticoagulant in blood cultures?
    toxic for many organisms (GP)
  31. why is heparin not used as an anticoagulant in blood cultures?
  32. these help bacterial recovery, couteract nor bactericidal mechanism of blood and causes turbidity.
    osmotic stabilizers
  33. what are the three osmotic stabilizers in blood cultures?
    • sucrose
    • mannitol
    • sorbitol
  34. what two things are used in blood cultures to absorb all antibiotics?
    • resin
    • activated charcoal
  35. what is used in blood cultures to inactivate penicillin?
  36. what is the purpose of a mycobacterial blood culture?
    to detect mycobacterium
  37. what are the two components of a mycobacterial blood culture?
    • middlebrook 7H9
    • automated system (Bactec MGIT)
  38. what temperature should blood culture media be stored at?
    room temperature
  39. scrupulous ____ preperation of venipuncture site is required.
  40. antiseptic should remain on the skin for how long?
    at least one minute
  41. how long should 70% alcohol be applied after palpation of the site?
    at least 30 seconds
  42. how much blood should be collected for blood culture?
    up to 20mL
  43. how much blood should be in each culture bottle?
    up to 10ml
  44. what are four contaminants of blood cultures?
    • stphylococcus epidermidis
    • propionbacterium acnes
    • diphtheroids
    • bacillus species
  45. how many samples should be collected in 24-48hrs to isolate?
  46. when should you collect two samples from two sites at the same time?
    if a patient is to be given antibiotics
  47. ______ culture is not enough to eliminate bacteremia
  48. what is the minimal dilution to unmodified medium for blood culture?
  49. how much blood should be drawn from an infant for blood culture?
    • 1-5 ml depending on weight
    • up to 4.5% of total blood volume
  50. the sterile needle and syringe method is an example of what collection system?
    open system collection
  51. if using an open system the sample should be injected into culture bottle where?
  52. using two syringes when collecting blood cultures reduces skin ______________.
  53. when blood is taken directly from patient via sterile transfer set directly into bottle it is an example of what system?
    closed system
  54. how long can blood cultures be refrgerated for before testing?
    two hours
  55. at what temperature should blood cultures be incubated?
  56. how long should routine aer/ana cultures be incubated for?
  57. how long should SBE cultures be incubated for?
    28 days
  58. how long should brucella cultures be incubated for?
    21-28 days
  59. how long should fungi be incubated for? at what temp?
    • 21-28 days
    • 30oC
  60. when should macroscopic/radiometric examination be performed?
    durring first 6-8 hours then daily
  61. what should aerobic cultures be subcultured to?
    • Choc 5-105 CO2 for 24-48hrs
    • BAP
  62. what medias should anaerobic cultures be subcultured to?
    shaedler's BAP
  63. when do you subcultue a blood culture?
    anytime culture turns positve macroscopically
  64. what is a self-contained subculture system called?
  65. what are the six portals of entry and their respective percentages?
    • GU tract 25%
    • respiratory- 20%
    • Abscesses- 10%
    • surgical wound- 5%
    • misc sites- 10%
    • uncertain sites- 25%
  66. what are the six commonly isolated GPC's?
    • S. epidermidis
    • S. aureus
    • Enterococcus spp
    • strep pneumoniae
    • viridans strep
    • beta strep
  67. what are the six commonly isolated GNR's?
    • Enerobacter cloacae
    • haemophilus influenzae
    • E. coli
    • P. aeruginosa
    • K. pneumoniae
    • proteus spp
  68. what is the commonly isolated yeast?
    C. albicans
  69. what are the two commonly isolated anaerobes?
    • B. fragillis
    • Clostridium spp.
  70. this is a group of fastidious GNR associated with infective endocarditis
  71. what are the bacteria in the HACEK group?
    • H. aphrobilus
    • A. actinomycetecomitans
    • C. hominis
    • E. corrodens
    • K. kingae
  72. what are four findings on a positive blood culture?
    • turbidity on medium
    • growth on RBC sediment
    • hemolysis
    • gas production
  73. how long is a stock culture maintained for?
    several months
  74. in what positive blood culture would you see uniform growth, turbidity or gas bubbles?
  75. in what positive blood culture would you see no change?
  76. in what positive blood culture would you see marked hemolysis, gas, and an unpleasant odor?
  77. in what positive blood culture would you see turbidity balls and jelly-like coagulum?
    S. aureus
  78. in what positive blood culture would there be a greenish tint to the medium?
  79. in what positive blood culture would there be marked hemolysis?
    beta strep
  80. in what positive blood culture would there be turbidity, foul odor, and less gas?
  81. in what positive blood culture would there be hemolyzed RBC's?
    bacillus spp
  82. in what positive blood culture would there be a thick pellicle on media surface?
    saprophytic fungi
  83. when is a blood culture considered negative?
    after three to four sets
  84. when do you report negative results?
    after 7 days
  85. what newer system monitors radio-labeled C14?
    radiometric (BACTEC) system
  86. what newer system monitors pH changes by colorimetric indicator?
  87. this newer system puts concentrate onto plate media allowing a faster, better recovery.
    lysis centrifugation