Resource Stewardship in Pediatric Endotracheal Aspirates: Modeled Financial, Environmental, and Laboratory Time Savings from a Gram Stain-Guided Stop Strategy

Abstract Corresponding Author Shreya Doshi – sdoshi@childrensnational.org No funding support, No conflicts of Interest. Background ETA cultures are frequently obtained yet often yield no clinical vlaue. Diagnostic stewardship has traditionally emphasized antimicrobial and clinical outcomes; however, respiratory culture workflows consume single-use plastics and generate regulated medical waste, commonly incinerated, contributing to air pollution. We modeled whether a Gram stain-guided stop strategy could reduce low-yield respiratory cultures, thereby expanding stewardship storytelling to include environmental, financial, and operational impact. Methods Using paired ETA Gram stain and semi-quantitative culture results from an existing QI project, we modeled savings when specimens with no organisms on Gram stain would receive Gram stain only (not proceed to plating or incubation). Environmental impact estimated using a partial life-cycle analysis limited to end-of-life treatment of a minimum initial culture setup (3 agar plates and 3 plastic loops/specimen) with directly measured weights and U.S. EPA emissions. Laboratory time savings were conservatively modeled as 20 minutes avoided/culture based on workflow observation. Financial impact was modeled as potential gross patient charge reduction if Gram stain alone were used. Results Per avoided culture (minimum setup), consumables = 0.044 kg mixed plastics & 0.049 kg mixed organics & total 0.116 kg CO₂e avoided per culture (combustion only; Table 1). Using a conservative denominator (no organisms on Gram stain AND no pathogen growth, n=664), modeled avoidance was 77.33 kg CO₂e, 221 technologist hours, & $271,576 in potential charge reduction (Table 2). Using an upper-bound denominator (no organisms on Gram stain, n=880), savings increased to 102 kg CO₂e, 293 hours, & $359,920 (Table 2). These correspond to approximately 193 & 256 miles driven, respectively. Conclusion A Gram stain-guided stop strategy could reduce low-yield ETA cultures and decrease single-use plastic consumption, technologist time, and patient charges. Environmental estimates show end-of-life combustion of minimum consumables and exclude upstream manufacturing, transport, laboratory electricity, regulated waste transport, and downstream culture work (subculture, ID, susceptibility testing), underestimating total impact. Future analyses should evaluate whether integrating waste and financial metrics into stewardship reporting influences clinician decision-making.