Post-pandemic Distribution Patterns of Respiratory Pathogens in Erzurum, Turkey: A Retrospective Analysis

Abstract

Background: This study aimed to investigate post-coronavirus disease 2019 (COVID-19) distribution patterns of respiratory pathogens using data from a tertiary care center in Erzurum, Turkey. Objectives: This study evaluated the post-pandemic distribution patterns of viral and bacterial respiratory pathogens detected by multiplex real-time polymerase chain reaction and described their associations with age, sex, and seasonal variation in patients with acute respiratory tract infections. Methods: This retrospective study analyzed respiratory samples submitted to Erzurum City Hospital between 2024 and 2025 for suspected acute respiratory tract infection. Pathogens were identified using a multiplex reverse transcription quantitative polymerase chain reaction panel targeting 15 viral and 5 bacterial agents and were analyzed according to age, sex, and season. A P-value < 0.05 was considered statistically significant. Results: A total of 3197 samples were analyzed. The median age was 6 years (interquartile range, 2 - 20 years), and 55.9% of the patients were male. Most samples were collected in winter. Respiratory syncytial virus (RSV) was the most commonly detected viral pathogen, followed by severe acute respiratory syndrome coronavirus 2 and influenza A virus. Streptococcus pneumoniae and Haemophilus influenzae were the predominant bacterial agents. Coinfections were observed mainly in children younger than 10 years, whereas adults more frequently had negative results and lower pathogen diversity. Respiratory syncytial virus, adenovirus, bocavirus, H. influenzae, Bordetella pertussis, and S. pneumoniae were associated with younger age (P < 0.05), whereas coronavirus NL63 was associated with older age (P < 0.001). Seasonal patterns showed that RSV and influenza A virus peaked in winter, influenza B virus peaked in spring, and severe acute respiratory syndrome coronavirus 2 was more prevalent in summer and autumn (P < 0.001). Conclusions: These findings demonstrate the re-emergence of RSV and influenza viruses, whereas severe acute respiratory syndrome coronavirus 2 circulation has shifted to lower levels. Bacterial detection by multiplex polymerase chain reaction requires cautious clinical interpretation. These data may inform diagnostic strategies and rational test use in acute respiratory tract infections.