Skin preparation is an important factor in reducing the rate of blood culture contamination. We assessed blood culture contamination rates associated with the use of skin antisepsis kits containing either 2% alcoholic chlorhexidine gluconate or 2% alcoholic tincture of iodine.

Prospective, blinded clinical trial.

Tertiary-care teaching hospital.

Adult patients in medical wards, the medical intensive care unit, and the cardiac intensive care unit who needed paired, percutaneous blood cultures.

House officers, medical students, and healthcare technicians drew the blood for cultures. We prepared sacks containing all of the necessary supplies, including two different types of antiseptic kits. In each sack, one kit contained 2% chlorhexidine in 70% isopropyl alcohol and the other contained 2% tincture of iodine in ethyl alcohol and 70% isopropyl alcohol. Each patient received chlorhexidine at one site and tincture of iodine at the other.

Four (0.9%) of 430 blood culture sets from 215 patients were contaminated. The contamination rate when using alcohol and chlorhexidine (1 of 215, 0.5%) did not differ significantly from the contamination rate when using tincture of iodine (3 of 215,1.4%; P = .62, McNemar test). There was an 87% probability that the two interventions differed by less than 2% in their rate of contamination.

Both of these antiseptic kits were highly effective for skin preparation prior to drawing blood for cultures. The use of these kits may have contributed to the low contamination rate observed in this study.