Diagnostic stewardship – optimization of superficial wound swab cultures can reduce the environmental impact of the microbiology laboratory

<b>Introduction.</b> Optimization of diagnostic testing is essential for the sustainable delivery of laboratory services. To date, little consideration has been given to the potential benefits of diagnostic stewardship to laboratories looking to reduce their environmental footprint. <b>Hypothesis.</b> Implementing a pre-analytical diagnostic stewardship intervention for the testing of superficial wound swabs would result in a measurable reduction in the environmental footprint of the microbiology laboratory. <b>Aim.</b> To assess the consequential impact of a diagnostic stewardship intervention on test volume, carbon footprint and quantity of non-recyclable plastic waste generated. <b>Methodology.</b> Superficial wound swabs received in the absence of clinical details suggestive of active skin and soft tissue infection were rejected by the laboratory. The carbon footprint of testing was estimated using Publicly Available Specification 2050:2011 methodology in a cradle-to-grave, attributional life-cycle assessment within a defined system boundary. The mass of laboratory plastic waste was calculated through the accurate weighing of associated laboratory consumables. <b>Results.</b> The intervention resulted in a reduction of 35.77 kg CO₂e and 9.06 kg of unrecyclable plastic waste over an 8-day period without measurable patient harm. <b>Conclusion.</b> This study demonstrates, in relation to specific testing pathways, that the optimization of microbiology laboratory diagnostic testing can result in a reduction in greenhouse gas emissions and non-recyclable plastic waste generation without negatively impacting patient care.