Specimen Requirements

Specimen RequiredSince media into which blood specimens are placed have been developed as enrichment broths to encourage multiplication of even 1 bacterium, it follows that these media will enhance growth of any stray contaminating bacterium such as normal inhabitants of human skin.
 

It is undesirable to draw blood through a vascular shunt or catheter since these prosthetic devices may harbor colonizing bacteria that are not present in circulating blood of patient. Blood obtained through foreign material would yield false-positive results. It is also recommended to draw blood below an existing intravenous line, if possible, since blood above the line will be diluted with fluid being infused.

Preparation of Patient and Collection of Blood
1. Draw blood at times indicated on order. If no specific times are indicated, collect 2 sets of cultures at same time in 2 consecutive venipunctures, each from a different site (preferably 1 from each arm) or collect 2 venipunctures from same site at intervals of 15 to 45 minutes.

2. One set of blood cultures is defined as 2 bottles (one aerobic with gray cap and one anaerobic with purple cap) or 1 bottle (pediatric bottle with pink cap) inoculated with blood drawn from 1 venipuncture.

3. If only 1 arm is available for blood collection, draw from 2 sites on same arm drawing a proximal (upper) site first, then a distal (lower) site, or alternatively, from same site at intervals of 15 to 45 minutes.

4. Apply tourniquet and select venipuncture site before disinfection (site may be marked with a fingernail).

5. Release tourniquet. (Proper disinfection takes more than 1 minute, and tourniquets left in place for more than 1 minute may cause erroneous results due to hemoconcentration).

6. Cleanse site using a Chloraprep® One-Step SEPP swab as follows:

A. Remove swab from kit. Hold in a horizontal position and pinch middle of applicator to break ampule. Press applicator tip against treatment area until liquid is visible on skin.

B. Use repeated back-and-forth strokes of applicator for 30 seconds. Completely wet area with ChloraPrep®. Allow to dry for at least 30 seconds. Do not wipe, blot, blow on or talk across area.

C. Discard applicator.

D. If anything touches site after preparation and before venipuncture, repeat disinfection process with a new ChloraPrep®.

7. While venipuncture site is drying, remove and discard the protective caps from blood culture bottle(s), then cleanse septa with a 70% isopropyl alcohol wipe. Do not use ChloraPrep® applicator to clean septa.

8. Perform venipuncture:

A. Apply tourniquet and locate vein.

B. Do not retouch site.

C. Collect blood using a butterfly needle and tubing set with a luer-lock adapter and tube holder. When more than 3 mL can be collected, draw aerobic (gray) bottle first, then anaerobic (purple) bottle second. Fill bottles to fill mark (optimum volume) while bottles are in an upright position. See Volume Requirements chart below.

D. Do not overfill (overfilling causes false positives readings).

E. Do not allow air to enter bottles. This will occur when taking needle out of arm before blood passes fill mark.

9. Remove tourniquet, withdraw needle from arm, apply pressure to site using a 3x3 gauze.

10. Label bottle(s) with patient’s name (first and last), specimen source, and date and time of collection.
11. Maintain sterility and forward promptly at ambient temperature only. Do not refrigerate.

Volume Requirements
Children have more bacteria circulating per mL than adults. Collect specimens using aerobic (gray) and anaerobic (purple) and pediatric blood culture bottles according to chart below.