Reducing blood culture contamination using an initial specimen diversion device

Abstract

False positive blood cultures result from contamination, consuming microbiological laboratory resources and causing unnecessary antibiotic treatment and lengthened hospitalizations. Skin sterilization has been shown to reduce contamination; however, bacteria do not only colonize the surface of human skin, but are also found in deeper tissues, requiring additional techniques to reduce contamination. An initial specimen diversion device diverts the initial 1-2 ml of blood so as to remove any potentially contaminated skin plug, thus potentially further reducing culture contamination. The device has been associated with a reduction in culture contamination over short study periods in certain populations. However, more study is needed to understand whether the effect continues over longer periods of time and in hospitalized patients. Thus, in this prospective, controlled pragmatic study, cultures were obtained from hospitalized patients using the initial specimen diversion device, with cultures taken using standard methods serving as control. In total, 671 blood cultures were obtained: 207 cultures were taken using an initial specimen diversion device, with 2 (1.0%) contaminated cultures and 464 cultures were taken without the device, with 24 (5.2%) contaminated cultures (p < 0.008). No significant difference was shown in the rate of true positive cultures. Thus, use of a diversion device was associated with reduced culture contamination in hospitalized patients over a six month period without concomitant reduction in true positive cultures. This intervention may result in a reduction in costs, antibiotic use and duration of hospitalization.