Blood mNGS strategies compared head-to-head in suspected sepsis

Metagenomic next-generation sequencing (mNGS) has become a powerful tool for identifying pathogens in patients with suspected sepsis, but a persistent obstacle has limited its accuracy: an excess of host-derived DNA in blood samples can drown out the genetic signals of the microbes clinicians are trying to detect.

Across the patient cohort, PB-HD mNGS showed relatively higher positive percent agreement than cfDNA mNGS, at 73.33% versus 66.67%. Negative percent agreement also favored PB-HD mNGS, at 62.63% versus 41.76%, and the same pattern held for overall percent agreement and for species matching consistency in cases where both tests were positive. The authors note that the two approaches interrogate distinct blood fractions, which is an important caveat when interpreting the comparison.

Notably, the study indicates a tendency toward better consistency between PB-HD mNGS and blood culture, the conventional diagnostic mainstay.

This revealed that cfDNA mNGS yielded higher positivity in patients with prominent systemic inflammatory activation, specifically those with elevated neutrophil proportion, C-reactive protein (CRP), and procalcitonin (PCT). In logistic regression analyses, CRP emerged as the only independent inflammatory marker correlated with cfDNA mNGS positivity and with positivity of the combined mNGS regimen.

Prognostic observations added a further layer of nuance. PB-HD mNGS positive results were observationally linked to prolonged ICU stay and higher in-hospital mortality, whereas cfDNA mNGS outcomes showed no statistical correlation with these endpoints. The authors describe these links as observational, and the study does not establish that mNGS results themselves influence outcomes; rather, they may reflect associations with underlying disease severity.

On the question of where each modality performs best, the study’s conclusions point to complementary roles. PB-HD mNGS presented relatively higher concordance with blood culture in suspected sepsis and focal infections, while cfDNA mNGS tended to show higher detection positivity in severe inflammation and in abdominal infection without lesion samples available for sampling.

Perhaps the most practically useful finding concerns the combined approach. The combination of PB-HD and cfDNA mNGS provides a robust alternative when invasive sampling is unavailable, according to the study’s conclusions.

Overall, the authors suggest that these findings imply clinicians may select appropriate mNGS modalities tailored to a patient’s inflammatory status and infection focus. As a prospective study of 121 patients with suspected sepsis and focal infections, the work offers a structured, head-to-head evaluation of two sequencing strategies that are increasingly discussed in intensive care settings, while its conclusions remain framed as tendencies and observations rather than definitive practice-changing recommendations.

Subject of Research: Comparing peripheral blood host depletion and plasma cell-free DNA metagenomic next-generation sequencing for pathogen detection in suspected sepsis

Article Title: Clinical application and performance evaluation of metagenomic next-generation sequencing for pathogen detection in patients with suspected sepsis: a prospective study

Article References: Huang, W., Qian, F., Chen, Y., Cai, Q., Li, T., Fang, Y., Sun, M., Li, Y., & Lu, Y. (2026). Clinical application and performance evaluation of metagenomic next-generation sequencing for pathogen detection in patients with suspected sepsis: a prospective study. BMC Microbiology. https://doi.org/10.1186/s12866-026-05876-x

Image Credits: AI Generated

DOI: 10.1186/s12866-026-05876-x

Keywords: sepsis, metagenomic next-generation sequencing, mNGS, host depletion, cell-free DNA, blood culture, pathogen detection, diagnostic performance, C-reactive protein, intensive care, prospective study, BMC Microbiology