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Diagnosis of sepsis from a drop of blood by measurement of spontaneous neutrophil motility in a microfluidic assay


Current methods for the diagnosis of sepsis have insufficient precision, causing regular misdiagnoses. Microbiological tests can help to diagnose sepsis, but are usually too slow to have an impact on timely clinical decision-making. Neutrophils have a high sensitivity to infections, yet measurements of neutrophil surface markers, genomic changes and phenotype alterations have had only a marginal effect on sepsis diagnosis. Here, we report a microfluidic assay that measures, from one droplet of diluted blood, the spontaneous motility of neutrophils in the presence of plasma. We measured the performance of the assay in two independent cohorts of critically ill patients suspected of sepsis. Using data from a first cohort, we developed a machine-learning-based scoring system (sepsis score) that segregated patients with sepsis from those without sepsis. We then validated the sepsis score in a double-blind, prospective case–control study. For the 42 patients across the two cohorts, the assay identified sepsis patients with 97% sensitivity and 98% specificity. The neutrophil assay could potentially be used to accurately diagnose and monitor sepsis in larger populations of at-risk patients.

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Fig. 1: A microfluidic device to assay spontaneous neutrophil motility from a droplet of diluted blood.
Fig. 2: Neutrophil spontaneous migration patterns that are specific to sepsis.
Fig. 3: Whole blood quality controls.
Fig. 4: Comparison of neutrophil behaviour in diluted whole-blood and isolated neutrophil assays.
Fig. 5: Whole-blood assays provide higher accuracy by retaining plasma factors.
Fig. 6: Segregation of clinical conditions using the sepsis score in the derivation and validation cohorts.

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We thank C. Holland and K. Brait for assistance in recruiting patients; M. Toner, H. S. Warren and M. Filbin for thoughtful discussions and advice; and D. Hayden for biostatistics assistance.This project was supported by funding from the National Institutes of Health, National Institute of General Medical Sciences (grant GM092804) and National Institute of Allergy and Infectious Diseases (grant AI113937), and Shriners Hospitals for Children. Biostatistics work was conducted in part with assistance from the Harvard Catalyst program, supported by a grant from the National Center for Advancing Translational Sciences (grant UL1 TR001102). Microfluidic devices were manufactured at the BioMEMS Resource Center at Massachusetts General Hospital, supported by a grant from the National Institute of Biomedical Imaging and Bioengineering (grant EB002503). F.E. was supported by a fellowship from Shriners Hospitals for Children.

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F.E. designed the study, designed and fabricated the microfluidic device, performed experiments, analysed the data and wrote the manuscript. J.J. performed experiments and cell tracking, analysed the data and applied machine-learning approaches to derive the sepsis score. J.J. and A.L.M. performed blood-spiking experiments. M.M.M., Y.M.L. and K.L.B. coordinated collection of patient samples for the first, derivation cohort and provided advice on the study design and manuscript. V.S. and J.L. coordinated collection of samples for the validation cohort and provided advice on the study design and wrote the manuscript. D.I. conceived, designed and supervised the study and wrote the manuscript.

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Correspondence to Daniel Irimia.

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Spontaneous motility of neutrophils in the microfluidic device.

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Ellett, F., Jorgensen, J., Marand, A.L. et al. Diagnosis of sepsis from a drop of blood by measurement of spontaneous neutrophil motility in a microfluidic assay. Nat Biomed Eng 2, 207–214 (2018).

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