Improving the Culture Surrounding Tracheal Aspirates in Mechanically Ventilated Children
Authors: Jelic Monika , Birkholz Meghan , Webber Matthew , Hamilton Stacey , Jung Sarah , Baker Christopher , Parker Sarah , Dominguez Samuel 
Published: January 2025

Corresponding Author: Monika Jelic, Pediatric Infectious Diseases, Children’s Hospital Colorado, 13123 East 16th Avenue, Box 055, Aurora, CO 80045, Phone: 720-777-6605, monika.jelic@childrenscolorado.org

Alternate Corresponding Author: Sarah Parker, Pediatric Infectious Disease, Children’s Hospital Colorado, 13123 East 16th Avenue, Box 055, Aurora, CO 80045, Phone: 720-777-8811, sarah.parker@childrenscolorado.org

Funding/Support: This study was supported by University of Colorado Institute for Healthcare Quality, Safety and Efficiency (IHQSE) Clinical Effectiveness and Patient Safety (CEPS) Grant Program.

Conflict of Interest Disclosures: Monika Jelic: No conflict, Meghan Birkholz: No conflict, Matthew Webber: No conflict, Stacey Hamilton: No conflict, Sarah Jung: No conflict, Christopher Baker: No conflict, Sarah Parker: No conflict, Samuel Dominguez: No conflict

Background

Tracheal aspirates are common specimens sent on mechanically ventilated children to aid in the diagnosis of tracheitis or ventilator associated pneumonia. The accuracy of tracheal aspirate cultures to diagnose lower respiratory tract infections is low, limited by normal respiratory flora contamination and variability in collection. Due to inconsistency in collection, processing, and reporting, many of these cultures are not clinically interpretable, and thus contribute to practice variation, overuse of antibiotics, and excess resource utilization, i.e. low value care. We targeted low value specimens through the implementation of Gram stain rejection criteria, aiming to decrease the overall number of tracheal aspirates cultured by at least 20% over 6 months.

Methods

We conducted a diagnostic stewardship quality improvement project from 2022 to 2024 at Children’s Hospital Colorado. Interventions included development of rejection criteria for Gram stains of tracheal aspirates, high use stakeholder department education and feedback on rejection criteria, implementation of Gram stain rejection criteria on April 3rd, 2023, and monitoring of tracheal specimens post intervention. Primary outcome was the change in rate per ventilated days of tracheal aspirate cultures performed. Secondary outcomes included rate of tracheal aspirate cultures that were clinically relevant, rate of specimens that were rejected for culture, and overall reduction in specimens sent for culture. For balancing measures, we monitored how many rejected specimens were cultured after provider request and how many of these cultures resulted in clinically relevant results.

Results

The implemented rejection criteria developed included not culturing tracheal aspirate specimens if initial Gram stain demonstrated moderate or heavy epithelial cells, no organisms, or three or more different Gram stain organism morphologies. We reviewed tracheal aspirates sent post intervention from April to December 2023. On average 134 tracheal aspirates were cultured per month in 2022 prior to our intervention and 43 were cultured per month after our intervention, resulting in a decrease of 68%. After our intervention, on average 58% of tracheal aspirate specimens were rejected and about 8.5% of these were cultured after rejection upon provider request. In our 9-month timeframe, 906 specimens were sent, 523 (58%) were rejected, 230 (25%) for no organisms and 293 (32%) for three or more different Gram stain organism morphologies. Of the 45 specimens cultured after rejection, all but one had 3 or more different Gram stain morphologies, 33% (15/45) grew only normal respiratory flora and 6 (13%) grew 1 or 2 predominant respiratory organisms without any normal respiratory flora.

Conclusions

Implementation of tracheal aspirate rejection criteria, a diagnostic stewardship strategy implemented within the clinical microbiology laboratory, decreased the number of unnecessary specimens cultured and improved the quality of specimens reported.