# Bronchoscopy Identifies Bacterial Airway Colonization and Comorbidities in Preschool Children With Refractory Respiratory Symptoms: A Retrospective Study

## TL;DR

Bronchoscopy in preschool children with persistent respiratory symptoms reveals frequent bacterial airway colonization and conditions like GERD.

## Contribution

This study highlights the role of bronchoscopy in identifying bacterial colonization and comorbidities in young children with chronic respiratory issues.

## Key findings

- Bacterial colonization was found in 61.7% of children, with Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis being the most common.
- Children with insufficient S. pneumoniae antibody titers had significantly more S. pneumoniae in BAL fluid.
- GERD was identified in 32% of children, and EoE in 2.8%.

## Abstract

Preschool children with refractory respiratory symptoms often undergo diagnostic bronchoscopy to exclude anatomical and functional abnormalities and to detect suspected chronic lower respiratory tract infections by bronchoalveolar lavage (BAL). The objective of this retrospective analysis was to analyze BAL fluid findings with respect to bacterial colonization and cytology. Additionally, we aimed to determine associations with bacterial colonization of the airways and allergic sensitization status and symptoms as well as to identify comorbidities like gastroesophageal reflux disease (GERD) or eosinophilic esophagitis (EoE).

In a retrospective analysis, the electronic medical records of 355 children aged 1–5 years who underwent bronchoscopy for refractory respiratory symptoms between 2010 and 2019 were evaluated. Differential cytology and bacterial cultures from BAL, laboratory parameters, oesophagogastroduodenoscopy (OGDS) and histology from esophageal biopsies were analyzed.

A positive bacterial culture from BAL fluid was found in 214 children (61.7%). Of these, 105 children (49%) subsequently received antibiotic treatment. The most frequently identified bacteria were Haemophilus influenzae (34%), Streptococcus pneumoniae (25%) and Moraxella catarrhalis (16%). The percentage of neutrophils in differential cell counts from BAL samples was significantly higher with positive bacterial cultures compared to negative cultures (29.2 + 28.1% vs. 21.2 + 25.4%, p = 0.02). Children with insufficient S. pneumoniae antibody titers had significantly more positive cultures for S. pneumoniae in BAL fluid (28.3% vs. 12.8%; p = 0.0024). GERD was identified in 115 children (32%) and EoE was diagnosed in nine children (2.8%).

Bronchoscopy is a valuable diagnostic tool in the evaluation of persistent respiratory symptoms in preschool children. Bacterial colonization of the airways was common and associated with significantly elevated airway neutrophil counts.