Epidemiology of microbiological findings in the lower respiratory tract in mechanically ventilated patients with and without inhalation injury.

Background: In mechanically ventilated burn patients, inhalation injury may increase the risk of lower respiratory tract colonization or infection with potentially pathogenic microorganisms and worsen in-hospital outcomes. Objective: We investigated the occurrence of potentially pathogenic microorganisms in lower respiratory tract samples and their association with in-hospital mortality in mechanically ventilated patients with and without inhalation injury. Methods: We conducted a retrospective observational study at a tertiary burn center (2007-2022) including patients who required mechanical ventilation for ≥2 days and sustained cutaneous burns and/or inhalation injury; clinical and microbiological data were extracted from medical records. Results: Among 311 mechanically ventilated patients, 305 had cutaneous burns, 168 had inhalation injury, and 180 had lower respiratory tract samples positive for potentially pathogenic microorganisms. Gram-positive bacteria predominated early during hospitalization, while gram-negative bacteria and fungi became more frequent over time. Patients with inhalation injury showed shorter time to in-hospital death than those without inhalation injury (mean 32 vs 64 days), regardless of total body surface area burned. Detection of extended-spectrum beta-lactamase-producing organisms was associated with higher mortality risk and substantially longer hospital stays. Conclusion: Inhalation injury was associated with a higher likelihood of lower respiratory tract positivity for potentially pathogenic microorganisms and with increased in-hospital mortality in mechanically ventilated patients.