Low Diagnostic Utility of Frequent Serial Tracheal Aspirate Cultures in the PICU*

To determine the diagnostic outcomes of serial tracheal aspirate cultures (TACs) in the PICU. DESIGN: A retrospective chart review of TAC utilization was performed. Items recorded for each TAC included the time and date of culture acquisition, result, changes in microbial resistance patterns, antimicrobial therapy, and patient clinical course. SETTING: A single urban tertiary care children’s hospital in the United States. SUBJECTS: Patients admitted to the PICU from January 1, to October 31, 2021, for whom a TAC was performed. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: One hundred fifty unique subjects had 582 TACs performed during the study period, of which 145 (24.9%) were serially repeated within 72 hours. Of these serial TACs, 82 (56.6%) had no growth, 41 (28.3%) grew the same organism as the prior culture, with most (36/41) displaying no major change in antimicrobial susceptibilities, 11 (7.6%) grew a new organism previously grown during the admission, and 11 (7.6%) grew a new organism not previously grown during the admission. Overall, only 26 of these serial TACs (17.9%) provided new diagnostic information, whereas only five (3.4%) led to a change in management. CONCLUSIONS: Frequent serial TAC sampling in the PICU is common and infrequently yields new data that impact clinical decision-making. Considering worsening antimicrobial resistance and the role of diagnostic stewardship in mitigating it, these findings further support a 72-hour reassessment period before performing a repeat TAC in critically ill children.