Background: Contaminated blood cultures (BC) generate avoidable costs and prolong hospital stays. To measure our hospital's performance against the recommended standard of <3% BC contamination, we performed a prospective study.
Methods: We prospectively determined the frequency of contaminated and genuinely positive BC hospital-wide over seven months.
Results: Overall, 73 of 1,829 blood cultures reviewed were contaminated (4.0%). However, distribution of contamination was not uniform. Finding a consistently higher incidence of contamination (11.7%) in our emergency department (ED) than elsewhere in the hospital (2.5%), we adopted a collaborative quality improvement strategy targeted to the ED. A combination of education, modified BC packs and regular feedback of BC results was associated with a significant reduction in contamination (7.4%, p=0.01) over the next six months. Our data suggests that contaminated BC were more likely to have been taken during regular day time hours (odds ratio (OR) 2.7, p=0.012), rather than overnight and were not associated with influxes of new junior medical staff. We found no evidence that the incidence of true bloodstream infection (12.8%) diagnosed by our ED was adversely affected by our intervention (10.7%, p=0.35).
Conclusions: Using a simple and inexpensive collaborative intervention we reduced BC contamination without adversely affecting the detection of genuine BSI.
Keywords: Blood culture; bloodstream infection; contamination; educational intervention; quality improvement.