9. Blood Cultures Flashcards by E E

organisms are always in the bloodstream, as in cases of septic shock, endocarditis, typhoid fever or when vascular hardware such as lines and catheters are infected.

Continuous bacteremia

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Minimum media setup for blood culture subcultures?

BAP /CO2
CHOC /CO2
BRUC /ANO2

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Organism? Associated w/ bowel cancer

Clostridium septicum

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most patients present with a flu-like illness that has lasted more than 2 weeks

Sub-acute endocarditis

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Organism? Acute endocarditis, line infections, abscesses

S. aureus

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4 organisms that are frequent blood culture contaminants

Bacillus
Coryne
P. acnes
CoNS

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rapid onset of symptoms, most patients are very ill with fever and malaise. Neurological abnormalities, stroke and subdural hemorrhage are not uncommon.

Acute endocarditis

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When collecting blood from children, we cannot collect ______ of total body volume

> 4%

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2 main additives in lysis-centrifugation tubes

Saponin - lyses RBCs, WBCs

SPS

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HACEK group is usually implicated in..?

Sub-acute infective endocarditis

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3 primary sites of intravascular bacteremia?

Endocarditis
IV catheters
Veins

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Includes bacteria and their toxins - always

Septicemia

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Due to congenital heart valve abnormalities

Sub-acute endocarditis

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Organisms associated w/ biofilm production on IV catheters

S. epidermidis

Other CoNS

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This antiseptic cannot be used on infants

Chlorhexidine gluconate

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Organisms are carried via _________ from the source in extravascular bacteremia

lymphatics

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Why are heparin, EDTA, and citrate UNACCEPTABLE anticoagulants in blood cultures

All toxic to organisms

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Purpose of 10% sucrose in blood culture bottles

Creates a hypertonic solution to support organisms that are cell wall-deficient

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Blood culture system that is not suitable for anaerobic culture

Biphasic bottles

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Ideal and acceptable contamination rate?

Ideal = < 1%
Acceptable = < 3%

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Why can’t you use chlorhexidine gluconate on infants?

Damages their skin

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Organism? Hospitalized and immunocompromised patients

Pseudomonads

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Organisms that usually cause bacteremia post-surgery or concurrent UTIs or in immunocompromised patients

Enterobacteriacea (mostly E. coli, K. pneumoniae)

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Max volume of blood that can be drawn from a child weighing < 36.3 kg?

No more than 20mL

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2 most common organisms implicated in subacute bacterial endocardiditis? Bacteremia type?

Viridans group of strep - S. mutans - S. sanguis Intermittent

What does SIRS stand for?

Systemic inflammatory response syndrome

Isolation of either of these 2 bacteria may suggest occult abscesses

- S. aureus | - Strep anginosis

range from minor disruptions like brushing our teeth, to major manipulations of the vascular system

Transient bacteremia

Isolation of this bacteria may suggest colon cancer

Streptococcus bovis

Approx. volume of blood in a blood culture?

10-15 mL

Purpose of 1.2% gelatin in blood culture bottles?

Counteracts SPS (but may be inhibitory to some organisms)

Organism? Endocarditis; associated w/ colon cancer

S. bovis

Sub-acute infective endocarditis is usually due to the __________ group and also _____

HACEK; small gnb

What to do if blood culture is NEG at day 5?

Blind sub to CHOC; keep plates for 3 days

organisms enter the bloodstream from another site of infection, for example from an abscess, deep wound or tumour

Intermittent bacteremia

Purpose of resins in blood culture bottles

Absorbs antibiotics without interfering w/ visual examination of cultures or smears

3 specific RE components in the circulatory system

- macrophages (produced in speen) - antibodies, complement fixation - WBCs (neutrophils and monos ingest bacteria, eosinophils target parasites)

Most positive blood cultures will show indication within ________ post-collection

9-18 hrs

Biphasic bottles ere initially developed for this organism

Brucella

What are the 4 types of endocarditis?

- Subacute bacterial endocarditis (SBE) - Prosthetic valve endocarditis - Acute infective endocarditis - Sub-acute infected endocarditis

Blood culture system w/ 2 separate chambers in a single containter

Biphasic bottles

Automated blood culture system that monitors gas pressure in each bottle

VeraTREK

Purpose of Middlebrook broth?

Specialized blood culture formula for AFB

Exotoxins are mainly produced by __________ bacteria

Gram positive

How to proceed if LESS than the recommended volume of blood is collected?

Inoculate the AEROBIC bottle first (most isolates are either aerobic or facultative anaerobes + yeast won't grow anaerobically)

Isolation of either of these 5 bacteria may suggest neoplasms

- Campy - Clostridium septicum - S. bovis - Aeromonas - Plesiomonas

CLSI recommendations for drawing blood with respect to endocarditis?

- 3 cultures over 30 mins - If neg at 24 hrs => draw an additional 2 sets on Day 2 Total = 5 sets

How is blood culture AST reported?

Verbally to physician to give a heads up (no written report)

Viridans in blood cultures is most often associated with what disease?

Sub-acute endocarditis associated w/ heart valve defects

Bacteremia where blood is not the primary focus of infection; organism seeds from abscess

Intermittent

Blood culture system that is best for pediatrics and why

Lysis-centrifugation system Detects atypical infections (most pediatric infections are atypical)

4 symptoms of septicemia

1. Fever and chills 2. Hyperventilation 3. Skin lesions (toxins) 4. Changes to mental state

Media used for blood culture AST?

Organism? Bacteremia primarily in hospitalized patients

Enterococci

Which 2 types of endocarditis involve a CONTINUOUS bacteremia pattern

The ones that have 'acute' in it - Acute infective endocarditis - Sub-acute infective endocarditis

3 ways bacteria can be introduced, causing transient bacteremia

- Infected site - Non-sterile body site - Subclinical infection

Best ratio of blood to culture broth?

1:5 But good up to 1:10

Primary host defense system that removes bacteria from circulation?

Reticuloendothelial system (RE system)

3 categories of bacteremia

- Transient - Intermittent - Continuous

Most important variable in detecting bacteremia and fungemia?

Volume of blood collected per draw

Organism? Mostly SBEs

CoNS

S. aureus is primarily implicated in this endocarditis

Acute infective endocarditis

Organism? Bacteremia in meninges, blood

N. meningitidis

Lysis-centrifugation tubes have these 2 additives

- Saponin (lyse RBCs, WBCs) | - SPS

Organism associated w/ IV catheters

S. aureus

Endotoxins are mainly produced by ________ bacteria

Gram negative

How often are negative blood culture reports generated?

Daily (@24 hrs, 48 hrs)

9. Blood Cultures Flashcards

(67 cards)