4CPS-072 Nebulised antibiotic therapy versus instilled antibiotic therapy in patients with tracheobronchitis

<h3>Background and Importance</h3> Ventilator-associated tracheobronchitis(VAT) is an intermediate stage between colonisation of respiratory tract and Ventilator-associated pneumonia(VAP). Some patients with VAT progress to develop VAP. VAT could be treated with topical antibiotic therapy alone. Vibrating mesh nebulisers were included in Intensive Care Unit(ICU) in September 2022. These devices can be used with the ventilation systems, allowing nebulised antibiotic therapy. Previously, antibiotics were administered by instillation. <h3>Aim and Objectives</h3> To assess whether nebulised antibiotic therapy in VAT is associated with a decrease incidence of VAP compared to instilled antibiotic therapy. <h3>Material and Methods</h3> We conducted a retrospective, non-interventional, longitudinal study. Critical patients with VAT treated with instilled antibiotic therapy from January 2021 to August 2022 and those treated with nebulised antibiotic therapy from September 2022 to June 2024 in the ICU of our centre were included. Patients receiving intravenous antibiotic therapy that was concomitant with nebulised or instilled therapy were excluded. Variables analysed: age, sex, date of admission to hospital, date of admission to ICU, date of diagnosis of VAT, nebulised/instilled antibiotic therapy, duration of nebulised/instilled antibiotic, microorganism treated, patients progress to VAP and date of diagnosis of VAP. Nebulised and instilled antibiotic therapy was compared using the χ² test. <h3>Results</h3> Thirty-eight ICU admissions of thirty-four patients were included, 73.5% were male. Age(median) was 65 years(IQR:52.8–78). Days from ICU admission to development of VAT (mean±SD) was 44±5.8 days. Mean duration of antibiotic therapy was 7±5.9 days, 44.7%(n=17) used nebulised antibiotics and 55.3%(n=21) used instilled antibiotics. Instilled antibiotics used were colistin 23.8%(n=5), gentamicin 23.8%(n=5), vancomycin 14.3%(n=3), amikacin 14.3%(n=3), cefotaxime 9.5%(n=2), ceftazidime 9.5%(n=2) and tobramycin 4.8%(n=1). Nebulised antibiotics used were vancomycin 35.3%(n=6), colistin 35.3%(n=6), amikacin 11.8%(n=2), gentamicin 5.9%(n=1), tobramycin 5.9%(n=1) and levofloxacin 5.9%(n=1). Microorganisms treated were <i>Pseudomonas aeruginosa</i>(26.3%), methicillin-sensitive<i> Staphylococcus aureus</i>(18.4%), <i>Serratia marcencens</i>(13.2%), <i>Stenotrophomonas maltophilia</i>(13.2%), methicillin-resistant <i>Staphylococcus aureus</i>(7.9%) and others(21%). Out of the five patients with VAT who developed VAP, three received inhaled therapy and two received nebulised therapy (non-significant differences,p=1). VAP occurred an average of 4.8±1.2 days after TAV diagnosis and VAP was caused by the same microorganism in four of the five patients. <h3>Conclusion and Relevance</h3> Progression of VAP in patients with VAT treated with nebulised and instilled antibiotic therapy is low. In this study, there is no difference between instilled and nebulised antibiotic therapy. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest