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Plasma versus whole blood multiplex droplet digital PCR for pathogen detection in ICU patients with clinically
Zhenping Wu1, Xinzeng Wang2, Jiang Xia3
1Department of Critical Care Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
Objectives:
Rapid pathogen identification remains challenging in critically ill patients with suspected sepsis. Droplet digital PCR (ddPCR) is a promising molecular diagnostic tool, but it is usually performed on plasma and may miss pathogen signals retained in cellular blood components. We therefore compared plasma and whole-blood ddPCR in ICU patients with clinically suspected sepsis.
Methods:
In this prospective multicenter cohort study, ICU patients with clinically suspected sepsis underwent paired plasma and whole-blood ddPCR together with blood culture. Blood culture-negative/ddPCR-positive cases were interpreted using structured clinical adjudication.
Results:
Among 223 patients, 62 (27.8%) had positive blood cultures. Both plasma and whole-blood ddPCR identified substantially more pathogens than blood culture alone and provided microbiological support for 38 and 46 adjudicated definite sepsis cases, respectively, among blood culture-negative patients. Overall performance was similar between matrices, but whole-blood ddPCR showed a higher detection rate for the Candida genus than plasma ddPCR (87.5% vs 31.3%, P = 0.03). Concordant positivity in both matrices was associated with greater disease severity.
Conclusion:
Both plasma and whole-blood ddPCR complement blood culture in ICU patients with clinically suspected sepsis. Although overall performance was similar, whole-blood ddPCR showed higher detection of the Candida genus in this cohort, a finding that requires validation in larger fungal sepsis cohorts.
Insights
Whole-blood droplet digital PCR (ddPCR) and plasma ddPCR offer improved pathogen detection in intensive care unit (ICU) sepsis patients compared to blood cultures alone. Whole-blood ddPCR showed a higher detection rate for Candida species.
Area of Science:
- Molecular Diagnostics
- Infectious Diseases
- Critical Care Medicine
Background:
- Rapid pathogen identification is crucial for critically ill patients with suspected sepsis.
- Droplet digital PCR (ddPCR) is a promising diagnostic tool, but its use in plasma may miss signals in cellular blood components.
- This study compares plasma and whole-blood ddPCR for sepsis diagnosis in ICU patients.
Purpose of the Study:
- To compare the diagnostic performance of plasma and whole-blood ddPCR in intensive care unit (ICU) patients with suspected sepsis.
- To evaluate the ability of ddPCR to identify pathogens missed by conventional blood cultures.
- To assess the utility of ddPCR in cases of blood culture-negative sepsis.
Main Methods:
- Prospective multicenter cohort study involving ICU patients with suspected sepsis.
- Paired plasma and whole-blood ddPCR assays were performed alongside standard blood cultures.
- Blood culture-negative, ddPCR-positive results were adjudicated using clinical data.
Main Results:
- Both plasma and whole-blood ddPCR identified more pathogens than blood culture alone.
- ddPCR provided microbiological support for 38 (plasma) and 46 (whole-blood) blood culture-negative sepsis cases.
- Whole-blood ddPCR demonstrated a significantly higher detection rate for the Candida genus (87.5%) compared to plasma ddPCR (31.3%).
- Concordant ddPCR positivity in both matrices correlated with increased disease severity.
Conclusions:
- Both plasma and whole-blood ddPCR complement blood culture for sepsis diagnosis in ICU patients.
- While overall performance was similar, whole-blood ddPCR showed superior detection of Candida species.
- Further validation in larger cohorts is needed to confirm the enhanced detection of fungal pathogens by whole-blood ddPCR.
