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Bacterial colonization and life-threatening respiratory syncytial virus infection in children

Eduardo L López1, Fausto Martín Ferolla1, Agustina F Denardi1

  • 1Hospital de Niños Ricardo Gutiérrez, Department of Medicine, Pediatric Infectious Diseases Program, University of Buenos Aires, Argentina.

Journal of Clinical Virology : the Official Publication of the Pan American Society for Clinical Virology
|November 28, 2025
PubMed

Insights

Bacterial colonization in young children significantly impacts respiratory syncytial virus (RSV) severity. Moraxella catarrhalis was linked to milder RSV disease, while Haemophilus influenzae showed a trend toward increased severity.

Area of Science:

  • Pediatric Infectious Diseases
  • Microbiome Research
  • Respiratory Virology

Background:

  • Respiratory syncytial virus (RSV) is a leading cause of severe acute respiratory infections in children.
  • The influence of bacterial colonization on RSV disease progression is not fully understood.
  • Understanding these interactions is crucial for managing pediatric respiratory illnesses.

Purpose of the Study:

  • To investigate the association between respiratory tract bacterial colonization and the severity of RSV infection in hospitalized children.
  • To identify specific bacterial species that may influence RSV disease outcomes.

Main Methods:

  • A prospective cohort study enrolled 172 children under 24 months with confirmed RSV infection.
  • Clinical data and respiratory samples were collected between 2019 and 2023.
  • Quantitative PCR (qPCR) was used to detect RSV, viral load, subtypes, and key bacteria: Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis.

Main Results:

  • Bacterial colonization was highly prevalent (92.4%) among RSV-infected children.
  • Moraxella catarrhalis colonization was associated with milder RSV disease (p=0.003).
  • Haemophilus influenzae showed a trend towards increased disease severity (p=0.054), while viral factors were not linked to severity. Household crowding independently predicted severe disease (p=0.031).

Conclusions:

  • Airway microbiota composition plays a role in modulating RSV disease severity in children.
  • Moraxella catarrhalis may be a key microbial determinant influencing the progression of RSV infections.
  • Further research into the airway microbiome's role in pediatric respiratory infections is warranted.
Abstract

Keywords:
Bacterial colonizationLife-threatening diseaseMoraxella CatarrhalisRSV

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