Relationship between respiratory tract microbiota dysbiosis and serum procalcitonin levels and clinical outcomes in patients with pneumonia

Lower respiratory tract infections remain a major problem worldwide.One biomarker that has long been used and is still used today is procalcitonin.Microbiota dysbiosis is a condition in which there is a shift in the number and proportion of the normal flora balance in the respiratory tract.However, to date, there have been few studies discussing respiratory tract dysbiosis in relation to serum procalcitonin levels and clinical outcomes in pneumonia patients.Lower respiratory tract infections remain a major problem worldwide.To analyze the relationship between respiratory tract microbiota dysbiosis and serum procalcitonin levels and clinical outcomes in pneumonia patients.This study is an observational analytical study with a crosssectional design involving 19 patients with pneumonia on mechanical ventilation in the intensive care unit of Dr. Soetomo General Hospital in Surabaya who met the study criteria.All samples were obtained between October 2024 and August 2025.An assessment of respiratory tract microbiota dysbiosis was performed on serum procalcitonin levels and clinical outcomes using BAL fluid samples No significant relationship was found between respiratory tract microbiota dysbiosis, as assessed using alpha diversity index, and serum procalcitonin levels and clinical outcomes, as determined using Spearman's rho statistical test, Mann-Whitney, and independent T-tests, with a statistical test value of p