Peripheral blood culture contamination in adults and venepuncture technique: prospective cohort study

Abstract

Aims: We tested the hypothesis that compliance with a hospital protocol on peripheral blood culture (PBC) collection in adults is associated with a reduction in PBC contamination, and also investigated likely contributing factors for contamination.

Methods: A prospective cohort study was conducted, utilising data collection by participant questionnaire completion, and utilising bacteriology laboratory results on PBCs. Participants were all health care workers involved in obtaining PBCs from adults.

Results:1460 PBCs with questionnaires were received. Contamination among the 1460 PBCs as a whole was 8.8%. 766 of the questionnaires were sufficiently complete to allow analysis of blood culture contamination in relation to protocol compliance. Amongst these, protocol compliance was 30% and contamination was 8.0%. When the protocol was complied with, 2.6% of PBCs were contaminated, but when the protocol was not followed, contamination was significantly higher at 10.3% (OR 4.35, 95% CI 1.84 to 12.54). Univariate analysis on all 1460 PBCs suggested that the site for blood collection, and disinfection of the venepuncture site were important factors in PBC contamination: when no venepuncture site disinfection was performed, contamination was significantly higher than when alcohol was used (5.2% versus 15.8%, odds ratio 3.46 with 95% CI to 2.01 to 5.97), and when a PBC collection site other than a fresh peripheral vein was used, contamination was significantly higher (7.3% versus 12.0%, odds ratio 1.75 with 95% CI 1.03 to 2.96).

Conclusions: Compliance with a hospital protocol on PBC collection technique in adults significantly reduces blood culture contamination.