Epidemiology of bacterial respiratory tract infections during the pre-pandemic, COVID-19 pandemic and post-pandemic era: A retrospective study of hospitalized adults in northern Greece between 2018 and 2023

Introduction: The COVID-19 pandemic has had impact on global healthcare and respiratory disease patterns. The aim was to evaluate the changes in positive respiratory cultures during the pandemic. Methods: A retrospective analysis of respiratory specimens in Papanikolaou Hospital during 2018-2023 was performed. In total, 18,852 samples (12,277 males, 6575 females) of respiratory samples were recorded. Results: During 2018-2019, 684 BAL samples were received, of which 12.3 % were positive. Positive pharyngeal smears constituted 24.8 %, compared to 18.5 % in pandemic years, and 29.6 % in 2023. In PTC, pre-pandemic, positives were 12.3 %, while in 2021 the maximum percentage of positives (21.9 %) was observed. Positive levels remained high in 2023 (18.3 %). Concerning bronchial secretions, there was an increase (55.3 % in 2022 vs 47.0 % in 2019). The predominant bacteria were Acinetobacter spp, Klebsiella spp and Pseudomonas spp. Conclusion: Except for the bronchial secretions, the rest of the respiratory specimens do not exhibit any definite trends.