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Updated: Dec 7, 2025
Murine Oropharyngeal Aspiration Model of Ventilator-associated and Hospital-acquired Bacterial Pneumonia
Published on: June 28, 2018
Temporal airway microbiome changes related to ventilator-associated pneumonia in children
Peter M Mourani1, Marci K Sontag2, Kayla M Williamson3
1Pediatrics, University of Colorado School of Medicine and Children's Hospital Colorado, Aurora, CO, USA.
Insights
Temporal changes in the lower airway microbiome in children on mechanical ventilation showed marginal associations with ventilator-associated pneumonia (VAP) risk. Higher total bacterial load correlated with lower VAP hazard, but microbial diversity changes were not predictive.
Area of Science:
- Microbiology
- Pediatric Critical Care
- Infectious Diseases
Background:
- Ventilator-associated pneumonia (VAP) is a significant complication in pediatric intensive care units.
- Understanding the role of the lower airway microbiome in VAP development is crucial for prevention and treatment strategies.
- Previous studies have explored microbial shifts in VAP, but temporal dynamics in pediatric populations require further investigation.
Purpose of the Study:
- To investigate the association between temporal changes in the lower airway microbiome and the incidence of VAP in children requiring mechanical ventilation.
- To identify specific microbial factors that may predict VAP development in this vulnerable patient group.
Main Methods:
- A multicenter prospective study enrolled children (31 days to 18 years) requiring mechanical ventilation for over 72 hours.
- Daily tracheal aspirates were collected and analyzed using 16S rRNA gene sequencing to assess microbial composition and total bacterial load (TBL).
- VAP diagnosis followed the 2008 CDC pediatric criteria, with statistical analyses including joint longitudinal time-to-event modeling, matched case-control, and unsupervised clustering.
Main Results:
- Of 366 subjects, 66 (15%) developed VAP. At intubation, VAP subjects had lower Shannon diversity and reduced relative abundance of Streptococcus, Lactobacillales, and Prevotella.
- Increased TBL on sequential days was associated with a decreased hazard of developing VAP (HR 0.39), while diversity changes were not significantly associated.
- Common VAP pathogens included Prevotella species, Pseudomonas aeruginosa, and Streptococcus mitis/pneumoniae. Mycoplasma and Ureaplasma were also identified.
Conclusions:
- Temporal changes in the pediatric lower airway microbiome were marginally associated with VAP risk but not sufficiently predictive for individual patients.
- While pathogen burden changes over time, relying solely on microbial load may not be adequate for VAP diagnosis in mechanically ventilated children.
- Further research is needed to elucidate the complex interplay between the microbiome and VAP pathogenesis in pediatric populations.
Abstract:
We sought to determine whether temporal changes in the lower airway microbiome are associated with ventilator-associated pneumonia (VAP) in children.Using a multicentre prospective study of children aged 31 days to 18 years requiring mechanical ventilation support for >72 h, daily tracheal aspirates were collected and analysed by sequencing of the 16S rRNA gene. VAP was assessed using 2008 Centers for Disease Control and Prevention paediatric criteria. The association between microbial factors and VAP was evaluated using joint longitudinal time-to-event modelling, matched case-control comparisons and unsupervised clustering.Out of 366 eligible subjects, 66 (15%) developed VAP at a median of 5 (interquartile range 3-5) days post intubation. At intubation, there was no difference in total bacterial load (TBL), but Shannon diversity and the relative abundance of Streptococcus, Lactobacillales and Prevotella were lower for VAP subjects versus non-VAP subjects. However, higher TBL on each sequential day was associated with a lower hazard (hazard ratio 0.39, 95% CI 0.23-0.64) for developing VAP, but sequential values of diversity were not associated with VAP. Similar findings were observed from the matched analysis and unsupervised clustering. The most common dominant VAP pathogens included Prevotella species (19%), Pseudomonas aeruginosa (14%) and Streptococcus mitis/pneumoniae (10%). Mycoplasma and Ureaplasma were also identified as dominant organisms in several subjects.In mechanically ventilated children, changes over time in microbial factors were marginally associated with VAP risk, although these changes were not suitable for predicting VAP in individual patients. These findings suggest that focusing exclusively on pathogen burden may not adequately inform VAP diagnosis.
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