Respiratory viruses in adult community-acquired pneumonia identified by a multiplex PCR panel: a single-center retrospective study.

BACKGROUND

Non-influenza and non-SARS-CoV-2 respiratory viruses are increasingly recognized as causes of adult community-acquired pneumonia (CAP), yet their distribution in routine clinical practice remains unclear.

METHODS

This single-center retrospective study included adult outpatients with radiographically confirmed pneumonia who underwent nasopharyngeal multiplex PCR testing (FilmArray Respiratory Panel 2.1) from March 2023 to December 2025. Tests positive for ≥1 of six target viruses were analyzed, excluding influenza viruses and SARS-CoV-2. Viral distribution and monthly case numbers were analyzed, and factors associated with multiple-virus positivity were explored.

RESULTS

Of 834 tests performed, 199 were positive for ≥1 target virus, and 161 had radiographically confirmed pneumonia. Among 169 viral detections from 161 tests, 153 were single-virus positive and eight were multiple-virus positive. Human rhinovirus/enterovirus (HRV/EV) was the most frequently detected virus (36.1%), followed by human metapneumovirus (18.3%), parainfluenza virus (PIV, 17.8%), and respiratory syncytial virus (RSV, 16.6%). An exploratory analysis demonstrated significant variation in viral distribution by month (Monte Carlo χ2 test, p < 0.0001). Among single-virus-positive cases, age differed significantly between RSV and seasonal coronavirus (p = 0.030), and sex distribution differed between PIV and RSV (p = 0.019) as well as between PIV and HRV/EV (p = 0.037). Although multiple-virus positivity was uncommon, it was independently associated with younger age in multivariable analysis (OR = 0.96, p = 0.041).

CONCLUSIONS

In routine CAP practice, diverse non-influenza and non-SARS-CoV-2 respiratory viruses were detected, with clear seasonal variation. Multiple-virus positivity was rare and associated with younger age.