From the Guidelines
Chlorhexidine gluconate is the preferred antiseptic for skin preparation before blood culture collection, due to its broader antimicrobial spectrum, faster action, and residual activity. A 2% chlorhexidine gluconate in 70% isopropyl alcohol solution is most effective, requiring a 30-second application with friction in a back-and-forth motion, followed by 30 seconds of drying time 1. This combination provides both rapid antimicrobial action from the alcohol and persistent activity from the chlorhexidine. For patients with chlorhexidine allergies, 70% isopropyl alcohol or povidone-iodine (10%) are acceptable alternatives, though they require longer contact times (1-2 minutes for povidone-iodine) 1.
The key points to consider when selecting an antiseptic for skin preparation before blood culture collection include:
- The antiseptic's ability to reduce the risk of skin contaminants entering the blood sample
- The antiseptic's spectrum of activity, with chlorhexidine gluconate being effective against a broader range of microorganisms
- The antiseptic's onset and duration of action, with chlorhexidine gluconate having a faster onset and longer duration of action than povidone iodine 1
- The potential for skin reactions or allergies to the antiseptic, with chlorhexidine gluconate having a lower incidence of skin reactions than povidone iodine 1
When collecting blood cultures, it's essential to:
- Cleanse the venipuncture site thoroughly with the selected antiseptic
- Avoid touching the area after disinfection to maintain sterility
- Draw blood for culture before initiating antimicrobial therapy
- Use a 2- to 3-bottle blood culture set for adults, at least one aerobic and one anaerobic 1
From the Research
Antiseptic Options for Local Skin Preparation
- Chlorhexidine and povidone-iodine are two commonly used antiseptics for skin preparation before blood collection for culture.
- A study published in 1999 2 found that chlorhexidine reduced the incidence of blood culture contamination more than povidone-iodine, with a contamination rate of 1.4% compared to 3.3% for povidone-iodine.
- Another study published in 2008 3 also found that 2% alcoholic chlorhexidine was superior to 10% aqueous povidone-iodine for venipuncture site disinfection, with a contamination rate of 3.2% compared to 6.9% for povidone-iodine.
Comparison of Chlorhexidine and Iodine Tincture
- A study published in 2002 4 found that skin antisepsis kits containing either 2% alcoholic chlorhexidine gluconate or 2% alcoholic tincture of iodine were associated with low rates of blood culture contamination, with no significant difference between the two agents.
- A prospective, randomized crossover study published in 2016 5 also found that chlorhexidine and iodine tincture were equivalent agents for blood culture skin antisepsis, with no significant difference in contamination rates between the two agents.
- However, a study published in 2019 6 noted that there is currently no solid consensus on the best antiseptic method for blood culture extraction, and that the chosen antiseptic may be irrelevant to the contamination rate if the blood culture extraction method is adequate and performed by a trained professional.