Characterization of multiple herpes viremia via next-generation sequencing in patients with lower respiratory tract infections: a retrospective cohort study

Lower respiratory tract infections (LRTIs) are a leading cause of the substantial morbidity and mortality associated with severe pneumonia. Herpesviruses (HHVs) frequently reactivate during critical illness, but their bronchoalveolar lavage fluid (BALF) coinfection patterns and clinical correlates remain incompletely defined. A retrospective cohort study was conducted among hospitalized adults with suspected LRTIs who underwent BALF next-generation sequencing (NGS) at the Yunnan First People’s Hospital between November 2024 and May 2025. Two analytical workflows were evaluated, namely metagenomic DNA sequencing (mNGS-DNA) and a targeted NGS (tNGS) panel, including 289 and 675 patients, respectively. Participants were subsequently classified into a herpesvirus-detected (HD) group and a non-herpesvirus-detected group (non-HD). In mNGS-DNA, detection frequencies were EBV 17.30%, CMV 14.88%, HHV-7 9.00%, HSV-1 8.30%, HHV-6 4.15%, and VZV 0.34%, single- and multi-virus positivity were 22.84% and 11.76%. In tNGS, the corresponding values were 17.93%, 12.00%, 7.11%, 10.07%, 2.96%, and 0.30%, single- and multi-virus positivity were 24.44% and 15.11%. HD patients were older and more likely to have severe pneumonia in both cohorts (P < 0.0001). Bacteria were the predominant pathogens in the patients with suspected LRTIs, followed by viruses and fungi. In matched BALF subsets, sequencing outperformed culture for bacterial detection (mNGS-DNA 37.90% vs. 20.56%; tNGS 87.45% vs. 13.45%; all P < 0.001), underscoring the complementary yield over conventional culture methods. HHVs exhibited the highest co-infection rates with pathogens such as Stenotrophomonas maltophilia, Klebsiella pneumoniae, and Candida albicans. In BALF from hospitalized LRTI patients, EBV and CMV predominate among herpesviruses, with HHV-7 a frequent coinfection partner. These findings underscore the need for prospective studies to define the prognostic impact of HHV coinfections.