Background: Quantitative or semi-quantitative assessment of neutrophils (microbiologic purulence-MP) is routinely reported for endotracheal aspirate cultures, but is not well standardized. The association of MP with symptoms of ventilator-associated infections or its role in guiding antibiotic therapy has not been well studied in the pediatric population. We examine MP as an independent predictor of antibiotic treatment and assess its association with clinical symptoms and ventilator-days.
Methods: Charts of children with positive endotracheal cultures sent from January to December 2016 from 3 PICUs were reviewed. The outcome variable was antibiotic administration for ≥5 calendar-days that targeted organisms identified in the culture. The predictor variable was MP defined as a neutrophil count reported as moderate/many by the clinical microbiology laboratory. Covariates included demographics, comorbidities including immunosuppression and recent surgery, changes in vital signs, respiratory support (including ventilator settings) and laboratory values (e.g. WBC count, C-reactive protein). Multivariable logistic regression was used to model the outcome.
Results: Of 361 positive endotracheal cultures in the cohort, 81 (22.6%) were treated with targeted antibiotics. Culture reports with MP were treated more frequently (30% vs. 10%). MP was the strongest predictor for ≥5 calendar-days of antibiotics (OR 3.3, 95% CI 1.6-6.8) followed by fever (OR 2.0, 95% CI 1.0-4.1), or increased respiratory support (OR 2.3, 95% CI 1.2-4.3). Compared with patients with MP reported as moderate/many, those without MP had similar rates of fever/hypotension (22% vs. 17%) and increased respiratory support (35% vs. 28%). Reported MP was lower with longer ventilator duration at time of sampling (Figure 1).
Conclusion: MP was an independent predictor of antibiotic use for positive endotracheal aspirate cultures, but was not associated with clinical symptoms or increased respiratory support. MP varied with ventilator-days at time of sampling. MP assessments lack intra- and inter-facility standardization and should be interpreted with caution when used as a rationale to prescribe antibiotics.
P. Zachariah, None
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