From the Guidelines
Yes, there is a specific protocol for withdrawing blood for bacterial blood culture, which should be performed with proper hand hygiene, wearing gloves, and disinfecting the venipuncture site with 2% chlorhexidine in 70% alcohol, as recommended by the most recent guidelines 1.
Key Steps in the Protocol
- The procedure should begin with proper hand hygiene and wearing appropriate personal protective equipment including gloves.
- The venipuncture site should be thoroughly disinfected with 2% chlorhexidine in 70% alcohol using a back-and-forth scrubbing motion for at least 30 seconds, allowing the antiseptic to dry completely, as supported by the guidelines 1.
- Blood should be collected using a sterile needle and syringe or a vacuum collection system, with the aerobic bottle filled first followed by the anaerobic bottle if using multiple bottles.
- The recommended volume is 10 mL of blood per bottle for adults, as this optimal volume increases the yield of detecting bacteremia, according to the guidelines 1.
Best Practices for Blood Culture Collection
- Two to three sets of blood cultures from different venipuncture sites are recommended, ideally before antibiotic administration, to maximize the chances of detecting bacteremia while minimizing contamination, as recommended by the guidelines 1.
- The bottles should be labeled immediately with patient information, date, time, and site of collection.
- The timing between sets should be within minutes if the patient is acutely ill, or may be spaced over several hours for subacute conditions.
Importance of Proper Technique
- Proper filling of blood culture bottles is important, as subpar filling can decrease yield, as noted in the guidelines 1.
- Contamination is likely if only a single blood culture set is positive for a microorganism that is a common contaminant, highlighting the need for multiple sets, as recommended by the guidelines 1.
From the Research
Protocol for Withdrawal of Blood for Bacterial Blood Culture
- The protocol for withdrawing blood from one patient for bacterial blood culture involves several steps to minimize contamination rates 2, 3, 4, 5, 6.
- Skin preparation is a crucial step, with studies comparing the effectiveness of different antiseptics such as chlorhexidine, povidone-iodine, and iodine tincture 2, 4, 5, 6.
- The use of 2% chlorhexidine in 70% alcohol has been shown to be superior to 10% aqueous povidone-iodine in reducing blood culture contamination rates 2, 4.
- Obtaining two bottles of ≥7 mL of blood from separate peripheral sites is recommended to maximize the utility of blood cultures 3.
- The clinical picture should take precedence in deciding whether to obtain blood cultures, and clinical prediction rules may be useful in predicting true positive cultures 3.
- Blood cultures should be obtained before antibiotic therapy begins to increase the yield of positive cultures 3.
Key Considerations
- Contamination rates can be reduced by using effective skin antiseptics and following proper protocols for blood culture collection 2, 4, 5, 6.
- The choice of antiseptic agent may not significantly impact contamination rates when blood cultures are obtained by a phlebotomy team 6.
- False-positive blood cultures can be associated with harm, including increased duration of stay and cost, emphasizing the importance of minimizing contamination rates 3.