Blood Culture Contamination A Randomized Trial Evaluating the Comparative Effectiveness of 3 Skin Antiseptic Interventions

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 (P= .18), 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.

Skin antiseptics in venous puncture-site disinfection for prevention of blood culture contamination: systematic review with meta-analysis

Blood cultures drawn by venous puncture are common clinical procedures for the detection of bacteraemia. Blood culture contamination (BCC) can lead to clinical misinterpretation and unnecessary expenses. We aimed to systematically review randomised controlled trials (RCTs) with skin antiseptics for prevention of contamination in venous-puncture drawn blood cultures. We conducted database search using CENTRAL (Cochrane Library issue April 2010), MEDLINE, EMBASE and mRCT, in June 2010. All RCTs testing skin antiseptics in venous-puncture drawn blood cultures were retrieved. Relative risk (RR) of the BCC outcome was analysed by random effects method using confidence interval (CI) of 95%. Studies were assessed by one review author and checked by another. Six studies were identified. Single-trial comparisons showed that alcoholic iodine tincture was better than non-alcoholic povidone-iodine, and isopropyl/acetone/povidone-iodine showed superiority against isopropyl/povidone-iodine. Meta-analysis demonstrated that alcoholic chlorhexidine was better than non-alcoholic povidone-iodine (RR: 0.33; 95% CI: 0.24-0.46) in 4757 blood cultures from two trials. Alcoholic solutions were better than non-alcoholic products (0.53; 0.31-0.90) in 21,300 blood cultures from four studies. Two trials with 13,418 blood cultures showed that iodine tincture was not superior to povidone-iodine in BCC prevention (0.79; 0.54-1.18). Alcoholic iodine was not different from non-alcoholic iodine (0.79; 0.53-1.17). Comparison of chlorhexidine vs iodine compounds was not conclusive. Alcohol alone was not inferior to iodinated products for prevention of contamination in venous-puncture drawn blood cultures. The association of alcohol and povidone-iodine did not seem to be useful. Alcoholic chlorhexidine solutions reduced blood culture false positives compared with aqueous povidone-iodine.