Bacterial targets dominate respiratory infections in hospitalized Chinese patients

Between December 2023 and December 2025, researchers at the Affiliated Hospital of Nantong University tested 5,808 patients hospitalized with acute respiratory tract infections, using multiplex real-time quantitative polymerase chain reaction to screen admission specimens for 16 pathogens. At least one pathogen was detected in 3,129 patients, or 53.87 percent of the cohort. Single-pathogen detections accounted for 2,103 patients (36.21 percent), while mixed detections of more than one pathogen occurred in 1,026 patients (17.67 percent).

The most frequently detected bacterial targets were Klebsiella pneumoniae, Staphylococcus aureus, and Haemophilus influenzae. The study team, writing in BMC Infectious Diseases, emphasized that molecular detection cannot distinguish active infection from colonization, so bacterial findings should be interpreted alongside clinical, culture, and biomarker data. The retrospective cross-sectional design also means the results describe hospitalized patients at a single eastern Chinese hospital rather than community infection rates.

Detection varied by infection site. After false discovery rate correction, six pathogens were more frequently detected in lower than in upper respiratory tract infections: Mycoplasma pneumoniae, adenovirus, human metapneumovirus, Haemophilus influenzae, parainfluenza virus type III, and influenza B virus, all with corrected q values below 0.05. In multivariable logistic regression adjusted for other factors, M. pneumoniae and H. influenzae remained associated with lower respiratory tract infections.

Age shaped the detection pattern markedly. Mycoplasma pneumoniae peaked among children aged 6 to 17 years, where it was detected in 30.92 percent of patients (81 of 262), with a statistically significant trend across age groups (P-trend < 0.001). This school-age concentration, the authors note, supports age-informed surveillance alongside seasonal monitoring.

Among patients with mixed detections, bacterial-bacterial pairs were the most frequent combinations, particularly Staphylococcus aureus together with Klebsiella pneumoniae. Co-detection patterns of this kind may complicate clinical interpretation, since the presence of multiple bacterial targets does not by itself establish which organism is driving disease.

Seasonality was most striking for influenza A virus, which showed a marked winter peak at 21.31 percent, compared with 1.20 to 2.54 percent in other seasons (q < 0.001). The study was designed to characterize pathogen spectra, clinical-site distribution, age-specific patterns, co-detection patterns, and seasonality after the relaxation of COVID-19 control measures, and its conclusion points to frequent bacterial-target detection, age-related heterogeneity, and distinct seasonal patterns among hospitalized patients in eastern China.

Subject of Research: Respiratory pathogen detection profiles and co-detection patterns among hospitalized patients with acute respiratory infections in Nantong, China

Article Title: Detection profiles and co-detection patterns of respiratory pathogens in hospitalized patients with acute respiratory infections after the COVID-19 pandemic in Nantong, China

Article References: Wu, T., Liao, W., Zhang, J., & Liu, Y. (2026). Detection profiles and co-detection patterns of respiratory pathogens in hospitalized patients with acute respiratory infections after the COVID-19 pandemic in Nantong, China. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14610-x

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14610-x

Keywords: respiratory pathogens, acute respiratory tract infections, Mycoplasma pneumoniae, influenza A, Klebsiella pneumoniae, co-detection, hospitalized patients, seasonality, Nantong China, multiplex PCR, surveillance, Detection