6 - Blood Cultures

Question 1

What do Blood Cultures help with

Answer 1

aid in the identifying the specific type of organism causing a bacterial or fungal bloodstream infection

A licensed practitioner may order the blood cultures to be drawn in sets of two or three. These are usually drawn 30 minutes apart and from different sites.

Specimens are placed in an incubator (an environmentally controlled device, usually set at 98.6° (37°C) to imitate normal body temperature) to allow time for microorganisms to grow, if present.

Question 2

• Antibiotic sensitivity tests and a blood cultures can provide what?

Answer 2

information to the physician about which antibiotic works the best against that particular species of bacteria.

• The Routine blood culture will recover aerobic and anaerobic bacteria and routine fungal isolates. It is suitable for those patients receiving antibiotic therapy.

help when people have fevers - Fever of Unknown origin - FUO

Question 3

Green - Bottle, volume and use

Answer 3

Bottle - BacT/Alert® Aerobic FA
Volume:10mL
Use:Aerobic- With broth, activated charcoal to remove growth inhibitors. Used in combination with Purple Top (Anaerobic) bottle for adult routine blood culture.

Question 4

Purple- Bottle, volume and use

Answer 4

Bottle - BacT/Alert® Anaerobic SN
Volume:10mL
Use:Standard anerobic broth. Used in combination with green Top (Aerobic) bottle for adult routine blood culture.

Question 5

Yellow - Bottle, volume and use

Answer 5

Bottle - BacT/Alert® Pediatric PF Aerobic
Volume: 4mL
Use: Pediatric volume aerobic -broth, with activated charcoal to remove potential growth inhibitors.

Question 6

Black - Bottle, volume and use

Answer 6

Bottle - MB/BacT® Blood Mycobacteria AFB
Volume: 5mL
Use: For Mycobacterial blood cultures - causes TB

Question 7

SITE PREPARATION

Answer 7

False positive results caused by skin flora contamination.

• False Negative results caused by insufficient blood and insufficient # of sets

• Blood culture contamination leads to unnecessary antibiotic therapy, additional laboratory testing, more frequent consultations, increased length of hospitalization and higher costs.
put touriniquet select site clean, reapply

Question 8

SAMPLE COLLECTION

Answer 8

• Blood cultures drawn immediately before and after a fever spike > 38 o C (give the most accurate information to the physician.)
• Blood cultures should be collected within one hour of order time. and if multiple about 30 mins apart – Always STAT

Helps to identify the specific microorganism that is causing the infection.

largest amount of orgs right before fever spike

Question 9

BABIES- PEDIATRIC BOTTLES

Answer 9

• Peds Bottle optimizes pathogen recovery
• Bottle accepts up to 5 ml
• Resins present to adsorb antibiotics
Anaerobes suspected?
• Inoculate 1 anaerobic bottle + Peds Plus bottle

Question 10

BLOOD VOLUME

Answer 10

• 0.5-2 ml Neonates
• 2-3 ml 1 Mth to 2 Yr
• 5 ml Older Children
• 10-20 ml Adolescents

BACTERIAL LOAD HIGHER IN CHILDREN THAN ADULTS

Question 11

< 20 kg ( Children)

Answer 11

1-2 mls

Up to 2 mls into (1) PF Culture Bottle.

Question 12

20 – 40 kg (Children)

Answer 12

4-10 mls

> 4 mls, divide evenly into (2 PF Culture Bottles.

Question 13

ADULT collection

Answer 13

• 10ml-20ml of blood for routine culture

Question 14

Two blood culture sets are collected at the same time

Answer 14

The second culture must be taken from a different site from the first and prepped in the same manner)

• A patient may have a total of four blood cultures (two sets) in the initial 48 hours of suspected sepsis.
• If a blood culture becomes positive, two additional “test of cure” blood cultures may be drawn 48 hours after notification of the positive culture.

Question 15

• Prepare Blood Culture Bottles

Answer 15

Remove flip caps from the culture bottles and disinfect the exposed septum with alcohol.

Question 16

Resins

Answer 16

in broth bind antibiotics can increase detection of some microorganisms.

ARD- antibiotic removal device - absorbs any antibiotic present

Question 17

Anticoagulant in bottles and other requirements

Answer 17

sodium polyanetholsulfonate (SPS)

 Bacteria produce CO2
 Ph sensor membrane at the bottom of the bottle
 A sensor dye in the bottle reacts with CO2
 Antibiotic neutralizer
 BACTEC photodetectors measure fluorescence
 Measurements occur every 10 minutes
 Incubate 35 +/- 2C. Detection in 5 days or less

Question 18

PATIENT PREPARATION

Answer 18

• First - Cleanse venipuncture site by using an alcohol wipe in a circular motion (most important step)
• Second - Next apply the chlorhexidine or povidone-iodine (Betadine) solution to the site in concentric circleimps allow the solution to dry for at least 30 -60 seconds.
Third - Alcohol
Some institutions require a third disinfection with alcohol.

Question 19

IODINE ALLERGY

Answer 19

Use chlorohexadine + alcohol

Question 20

Order of draw

Answer 20

Winged Infusion (butterfly)
 (1)  BacT/Alert bottle (aerobic) 
(2)  BacT/Alert bottle (anerobic)  or yellow SPS vacutainer tube
(3) Other tubes 
Syringe: Anaerobic, then aerobic
•	Collect the correct volume

Question 21

BLOOD CULTURE SPECIMEN LABEL

Answer 21

Patient full name 
Unique ID number
Date
Time
Lab Number
Site Location( left arm , left hand etc.)
Site Number (site 1or 2)
Technician initials
TRANSPORTATION & INCUBATION

Transport the blood culture bottles to the Microbiology Laboratory within one hour.
Incubate 5 DAYS 35+/-2C

Question 22

POSITIVE CULTURE NOTIFICATION

Answer 22

A positive culture indicator light and alarm
May see discoloration or to yellow colour at the bottom of bottle
A Gram stain and a subculture should be performed from each positive vial.

Question 23

not cleaning on infant < 2 months old

Answer 23

• .5% Chlorhexidine gluconate preps

Question 24

Cleaning For infant blood cultures or blood alcohol collections

Answer 24

• Betadine or 2 %iodine wipes

if you use iodine …remove the iodine with alcohol

Question 25

E coli

Answer 25

present in low amounts in the blood so they need a larger amount of blood to be found - if volume too low than you can get a false negative