A national audit of performance standards for blood cultures in Aotearoa New Zealand: opportunities for improvement

Abstract

Aims: To audit key quality indicators for blood culture (BC) practices across Aotearoa New Zealand to facilitate national BC practice peer review and promote BC quality improvement interventions.

Method: Microbiology laboratories providing diagnostic services to district health board (DHB) hospitals were invited to participate. Practice was compared against published BC recommendations. Laboratories were required to submit data for BC positivity and contamination rates, BC bottle fill volume and the proportion of BC received as a single set.

Results: Laboratories serving 15 of the 20 DHBs participated in the audit. Nine DHBs (60%) demonstrated a positivity rate within the target range of 8% to 15%. Eight DHBs (53%) reported a contamination rate lower than the accepted 3%, but seven (47%) DHBs exceeded this target and two reported a contamination rate greater than 5%. Mean BC bottle fill volumes were generally greater than the target of 8mL, but this volume was not reached by three DHBs and a further three were unable to provide fill volume data. No DHB met the audit standard for single-set BCs representing <20%, and for six DHBs single-set BC comprised more than half of all samples. No DHB failed all audit targets.

Conclusion: This audit demonstrates wide variation in BC performance across New Zealand. In most instances an inadequate volume of blood is being collected, lowering the chance of culturing a pathogen. A significant opportunity for improvement exists; clinical services and laboratories are encouraged to work together to implement targeted quality improvement processes to correct deficiencies in practice.