Epidemiological and etiological characteristics of respiratory infections among hospitalized patients: insights from a 12-pathogen surveillance study in eastern China

Background Severe acute respiratory infections (SARIs) pose a significant global public health threat, yet their pathogen profiles and epidemiological characteristics vary regionally. Lianyungang, a temperate monsoon climate region in eastern China, lacks comprehensive data on the etiological composition and coinfection patterns of respiratory infections. To improve clinical management and preventative measures, this study sought to examine the distribution of pathogens and coinfection trends among hospitalized patients in this region. Methods A retrospective analysis was conducted on 2,132 hospitalized patients with respiratory infections at a comprehensive hospital in Lianyungang from January to December 2024. Respiratory samples (throat swabs and sputum) were collected and tested via multiplex PCR for 12 pathogens, including influenza A virus, influenza B virus, respiratory syncytial virus, adenovirus, human rhinovirus, M. pneumoniae, K. pneumoniae , S. pneumoniae , H. influenzae , P. aeruginosa , L. pneumophila , and S. aureus . Demographic characteristics, seasonal trends, departmental differences, and coinfection patterns were analyzed. Results Pathogens were detected in 61.73% (1,317/2,132) of patients, with bacterial dominance (71.34%). S. pneumoniae (25.60%), H. influenzae (18.55%), and K. pneumoniae (12.36%) were the most prevalent. Viral pathogens exhibited the highest prevalence in pediatric populations (75.60%), with rhinovirus, respiratory syncytial virus, and adenovirus dominating in 0–4-year-olds. Mycoplasma pneumoniae detection significantly increased in 5–14-year-olds (38.89%), whereas bacterial infections predominated in patients over 15 years of age. Male patients significantly outnumbered female patients (61.35% vs. 38.65%), with higher S. pneumoniae detection in males (27.98% vs. 21.41%). The peak hospital visits (42.14%) were recorded in winter, with S. pneumoniae circulating year-round. Influenza B virus and M. pneumoniae levels peak early in the year, whereas influenza A virus levels increase markedly late in the year. Mixed infections occurred in 33.79% of the cases, predominantly bacterial‒bacterial combinations (68.31%), such as S. pneumoniae-H. influenzae coinfections. Rhinovirus frequently appeared in bacterial–viral coinfections (38.71%), whereas influenza A virus dominated viral–viral combinations (44.44%). Conclusion This study highlights bacterial predominance, age-specific pathogen distributions, and high coinfection rates in Lianyungang. The findings underscore the need for age- and season-tailored clinical management, enhanced viral testing in pediatrics, and prioritized pneumococcal vaccination for elderly individuals. These insights provide critical evidence for optimizing local antimicrobial stewardship and public health strategies in regions with similar climates.