Blood culture contamination: a randomized trial evaluating the comparative effectiveness of 3 skin antiseptic interventions

Abstract

Objective: To determine relative rates of blood culture contamination for 3 skin antisepsis interventions-10% povidone iodine aqueous solution (PI), 2% iodine tincture (IT), and 2% chlorhexidine gluconate in 70% isopropyl alcohol (CHG)-when used by dedicated phlebotomy teams to obtain peripheral blood cultures.

Design: Randomized crossover trial with hospital floor as the unit of randomization.

Setting: Teaching hospital with 885 beds.

Patients: All adult patients undergoing peripheral blood culture collection on 3 medical-surgical floors from May 2009 through September 2009.

Intervention: Each antisepsis intervention was used for 5 months on each study floor, with random crossover after a 1-month washout period. Phlebotomy teams collected all peripheral blood cultures. Each positive blood culture was adjudicated by physicians blinded to the intervention and scored as a true positive or contaminated blood culture. The primary outcome was the rate of blood culture contamination for each antisepsis agent.

Results: In total, 12,904 peripheral blood culture sets were evaluated, of which 735 (5.7%) were positive. There were 98 contaminated cultures, representing 13.3% of all positive cultures. The overall blood culture contamination rate for the study population was 0.76%. Intent-to-treat rates of contaminated blood cultures were not significantly different among the 3 antiseptics ([Formula: see text]), yielding 0.58% with PI (95% confidence interval [CI], 0.38%-0.86%), 0.76% with IT (95% CI, 0.52%-1.07%), and 0.93% with CHG (95% CI, 0.67%-1.27%).

Conclusion: Choice of antiseptic agent does not impact contamination rates when blood cultures are obtained by a phlebotomy team and should, therefore, be based on costs or preference.

Trial registration: ClinicalTrials.gov identifier: NCT01216761 .