Blood culture contamination: Randomized trial evaluating the comparative effectiveness of 3 skin antiseptics


Intravenous literature: Washer, L.L., Chenoweth, C., Kim, H., Rogers, M.A.M. Malani, A.N., Riddell, J., Kuhn, L., Noeyack Jr, B., Neusius, H., Newton, D.W., Saint, S. and Flanders, S.A. (2013) Blood Culture Contamination: A Randomized Trial Evaluating the Comparative Effectiveness of 3 Skin Antiseptic Interventions. Infection Control and Hospital Epidemiology. 34(1), p.15-21.


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 ( ), 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.? identifier: NCT01216761 .

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