# Baseline Characteristics of Bronchial Secretions and Bronchoalveolar Lavage Fluid in Patients with Ventilator-Associated Pneumonia

## TL;DR

This study compares clinical and molecular features of ventilator-associated pneumonia caused by drug-resistant and non-resistant bacteria to help improve diagnosis and treatment.

## Contribution

The study identifies distinct immunological profiles in non-MDR-VAP patients compared to MDR-VAP patients using bronchial secretion and BAL fluid analysis.

## Key findings

- VAP patients had higher APACHE II scores and airway pressure compared to non-VAP patients.
- Non-MDR-VAP patients showed increased BAL protein, IL-1β, and cellular levels compared to MDR-VAP patients.
- Macrophages and polymorphonuclears were significantly elevated in VAP compared to non-VAP patients.

## Abstract

Mechanically ventilated (MV) patients often develop ventilator-associated pneumonia (VAP) with increased mortality risk, especially in VAP caused by multidrug-resistant (MDR) microorganisms. We evaluated MV patients and monitored VAP presentation, microbiologically confirmed. The patients underwent bronchoalveolar lavage (BAL) and blind bronchial aspiration (AC) at baseline. Systematic bronchial secretion and radiologic assessments were performed daily. The patients were classified as MDR-VAP, non-MDR-VAP, or non-VAP. The APACHE II and SOFA scores, microbiology, inflammatory markers, respiratory system characteristics, and ventilator settings were evaluated. BAL and AC were assessed for total protein levels, cellular number and profile, and IL-1β and TNF-α levels. Of the VAP patients, 46.1% presented with MDR-VAP due to Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae, or Stenotrophomonas maltophilia, and 53.8%—with non-MDR-VAP. The VAP patients had higher APACHE II scores and airway pressure but a lower baseline PO2/FIO2 compared to the non-VAP patients, while PO2/FIO2 was increased in MDR-VAP compared to non-MDR-VAP. BAL protein, IL-1β, and cellular levels were increased in VAP vs. non-VAP and in non-MDR-VAP compared to MDR-VAP. Macrophages and polymorphonuclears were 34.36% and 23.76% in VAP, statistically significant increased compared to non-VAP. Their percentages were also increased in non-MDR-VAP compared to MDR-VAP. These differences imply a different immunological profile in non-MDR-VAP patients. In conclusion, MDR-VAP patients may present significant differences in baseline clinical characteristics and molecular biomarkers, which may help in prompt diagnosis and an improved therapeutic approach.