Order Information
This order enables diagnosis of a catheter-related bloodstream 
infection through comparison of the differential time to positivity 
between cultures drawn from a central line and a venipuncture.  
Because bacterial load is highest at the origin of the infection (the 
catheter), a definitive diagnosis of CRBSI is made when identical 
organisms are recovered from the catheter and peripheral cultures and 
the catheter culture is positive greater than or equal to 2 hours 
earlier than the peripheral culture.  This "differential time to 
positivity" can be calculated from the time to positivity reported for 
each set in Epic.

In diagnosing a catheter-related bloodstream infection (CRBSI) 
multiple sets of bottles and a peripheral venipuncture are REQUIRED.  
For a single draw from a catheter without a venipuncture please use 
Epic order LAB8383: BLOOD CULTURE - ADULT instead.

Recommendations
[1] Fill bottles with equal volumes so that differential time to 
positivity is accurately calculated.

[2] Volume of blood cultured is the primary determinant of whether 
bloodstream infection is detected.  For suspected CRBSI, a minimum of 
2 sets of bottles should be sent before initiation of antimicrobial 
therapy and the bottles should be appropriately marked to reflect the 
site from which the samples were obtained.  For this order, two 
venipunctures and one sample drawn through any lumen of a catheter are 
ideal.

[3] If no blood sample can be drawn from a venipuncture it is 
recommended that at least 2 sets should be drawn through different 
catheter lumens.  In this case, check the boxes next to the "site #1, 
catheter" and "site #4, catheter" orders and fill in the source 
(e.g. "red lumen" or "PICC") for each in the individual orders that 
result.  If a venipuncture cannot be obtained for what was intended to 
be a catheter draw, the documented source (catheter) will override the 
source on the initial order (venipuncture).

General Recommendations
[1] For procedures, refer to Nursing Policy & Procedure (N-03.020).

[2] To maximize volume, use the phlebotomy protocols listed under 
Reference Links.

[3] If molds, Blastomyces, Histoplasma, Nocardia, or Malassezia spp. 
are suspected, 3 orders (ideally) should be placed for Microbiology: 
Fungus Blood Culture (LAB2217) as these organisms are not detected 
well by typical blood culture.  For Malassezia, which is sometimes 
associated with catheters used for CVN/TPN, specify (free text) that 
this fungus is under consideration so specific cultures are set up.  
For detection of Candida catheter-associated bloodstream infection a 
fungal culture is unnecessary and inefficient: instead, draw the 
volume above and inoculate into two aerobic bottles (no anaerobic 
bottles).