Bloods Bench Flashcards
presence of bacteria in the blood
bacteremia
bacteria passing through (dental, colonoscopy)
transient bacteremia
bacteria seeding from the infected site to another area intermittently (seeding blood) (same organism off and on)
intermittent bacteremia
Bacteria coming from an intravascular source all of the time (endocarditis)
continuous bacteremia
bacteremia with organisms multiplying in the blood and symptoms showing
septicemia
Sepsis going on inside a site such as an iv catheter, endocarditis
primary sepsis
Sepsis going on in an external site such as strep from lungs, UTI, dental surgery, tooth abscess…
secondary sepsis
Clinical signs or symptoms that can be associated with septicemia
fever (i or d) shaking chills malaise tachypnea prostration (laying down) blood pressure (i or d) DIC WBC count (i or d) lactic acidosis C-RP (i) procalcitonin (indicator of inflammation)
Indicators for obtaining blood cultures
*
What criteria are used in the selection of a site for collection of blood cultures
- draw opposite are that has iv
- draw below iv if have to draw from arm with iv
What is the number of collections and the appropriate time during the progression of a disease that a blood vulture should be drawn?
Number: one set = 1 aerobic bottle and one anaerobic bottle; no more than 3 sets in 24 hours (inoculate aerobic first)
- draw before antibiotic therapy
- space drawings an hour apart; if not, draw from different sites
What is the blood to medium ratio that is recommended for inoculating blood culture bottles and the rationale for this ratio
1 : 5 - 1 : 10
What precautions should be taken in the collection and handling of blood cultures?
*
What are the four macroscopic (observable) characeristics that would be evidence of growth in a conventional broth blood culture bottle?
*
Purposes of Sodium Polyanetholsulfonate (SPS) in blood culture bottles
anticoagulant
Purposes of resins in blood culture bottles
neutralizes antibiotics
What types of organisms may be better isolated from a Lysis Centrifugation (Isolator) System?
intracellular pathogens
- fungi
- yeasts
- molds
What is the rationale for using the Lysis Centrifugation (Isolator) System?
saphonin lysis white blood cells
What media and biochemicals should be used when blood culture is positive for:
- GPCs
BAP
CHOC
ANA BAP
What media and biochemicals should be used when blood culture is positive for:
- GPRs
BAP CHOC ANA BAP (Lacto) TJ (Bacillus) PEA (Coryne) First three tubes only
What media and biochemicals should be used when blood culture is positive for:
- GNRs
BAP CHOC MAC CNA ANA BAP - KIA FROM BLOOD or Vitek
What media and biochemicals should be used when blood culture is positive for:
- GNCs
BAP
CHOC
ANA BAP
ML
What media and biochemicals should be used when blood culture is positive for:
- yeast (YLF)
BAP CHOC ANA BAP CSAB CAC
What do you do if a blood culture bottle is signaled as positive by the BACTEC but no organisms are seen on the gram stained smear (“false positive”)
Negative GS and acridine orang stain:
- Subculture vial medium to CHOC and ANA BAP and incubate
- Return Vial to instrument
Length of incubation and intervals of subculture for isolation of Brucella
- Held for 14 days in the Bactec FX
- subcultured weekly to trypticase soy agar; these plates are held for four days in CO2 incubator
- If sent in an ISOLATOR tube, it is plated to a BAP, CHOC , and TSA plate and held for 14days
Length of incubation and intervals of subculture for isolation of Bartonella
vials are held for 30 days in the BACTEC FX
How long are NEGATIVE blood bottles held on the BACTEC?
5 days
What are the 3 most common agents of subacute bacterial endocarditis (SBE)
- CoNS
- Viridans strep
- (staph aureus)
What are the most common GPC and GPR contaminants in blood cultures?
- alpha/gama strep (viridans)
- CoNS
- Proprionibacterium acnes
- Corynebacterium
Principle of the PNA/Quick FISH testing
*
Purpose of the PNA/Quick FISH testing
*
Common signs of a blood pathogen
- positive on the first day
- with multiple specimen all bottles are positive
Common signs of a blood contaminant
- positive on the fifth day
- with multiple specimen 1 out of all bottles is positive
What are two “Limitations of Method” that could lead to false positive or false negative blood culture results
FN: overfill (>10mL adults &>4mL pediatric) can result in inadequate oxygenation of aerobic culture bottles / also may lead to blood to medium ratio that may cause decreased recovery and detection of certain organisms
FP: due to very high number of WBCs being present in blood culture sample
Recommended procedure to follow when drawing a blood culture
- Vigorously cleans the site by rubbing in concentric circles with alcohol
- rub in concentric circles using iodine for one to two minutes
- Do not touch the site
What type of toxin is responsible for “Gram negative shock” and its significance for patients with positive blood cultures
*
What is Neisseria meningitidis’ associated disease?
*
What is Listeria’s associated disease?
*
What is Clostridium septicum’s associated disease?
*
What is Brucella’s ‘ associated disease?
*
What is Bartonella’s associated disease?
*
