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Background: Among children with tracheostomies, little is known
about how respiratory culture results differ between states with and
without acute respiratory infections (ARI), or the overall test
performance of respiratory cultures.
Objective : To determine the association of respiratory culture
organism isolation with diagnosis of ARI in children with
tracheostomies, and assess test characteristics of respiratory cultures
in the diagnosis of bacterial ARI (bARI).
Methods : This single-center, retrospective cohort study
included respiratory cultures of children with tracheostomies obtained
between 2010-2018. The primary predictor was ARI diagnosis code at the
time of culture; the primary outcomes were respiratory culture organism
isolation and species identified. Generalized estimating equations were
used to assess for association between ARI diagnosis and isolation of
any organism while controlling for potential confounders and accounting
for within-patient clustering. A multinomial logistic regression
equation assessed for association with specific species. Test
characteristics were calculated using bARI diagnosis as the reference
standard.
Results : Among 3,578 respiratory cultures from 533 children
(median 4 cultures/child, IQR: 1-9), 25.9% were obtained during ARI and
17.2% had ≥1 organism. Children with ARI diagnosis had higher odds of
organism identification (aOR 1.29, 95% CI 1.16–1.44). When controlling
for covariates, ARI was associated with isolation of H.
influenzae, M. catarrhalis, S. pneumoniae, and S. pyogenes . Test
characteristics revealed a 24.3% sensitivity, 85.2% specificity,
36.5% positive predictive value, and 76.3% negative predictive value
in screening for bARI.
Conclusion : The utility of respiratory culture testing to
screen for, diagnose, and direct treatment of ARI in children with
tracheostomies is limited.