Benchmarking blood culture quality in the emergency department: Contamination, single sets and positivity

Abstract

Objective: To benchmark blood culture (BC) quality in an Australian ED, explore groups at risk of suboptimal BC collection, and identify potential areas for improvement. Methods: This retrospective observational study was undertaken to benchmark quality of BCs in a tertiary adult ED in terms of number of BC sets per patient and proportion of patients with false positive (contaminated) BC results. Results: A single BC set was taken for 55% of patients, with lower acuity patients being more likely to have a single BC set taken. BC false positives occurred in 3.4% of presentations, with higher frequency in some critically unwell patient groups. The true positive BC rate was 10.9%, with pathogens most frequently isolated in older patients, those with a haematological condition or genitourinary source, and those admitted to inpatient wards. Hospital length of stay did not differ between patients with negative and patients with false positive BCs. Conclusions: BC quality standards in the ED such as false positive rate <3% and single culture rate <20% are required to facilitate benchmarking and prospective quality improvement. The sensitivity and specificity of this common and critical test can be improved. Patient subgroups associated with poor-quality BC collection can be identified and should be a focus of future work.