PROJECT SUMMARY
Sepsis is not only the most expensive condition treated in US hospitals, but also a leading cause
of death. Sepsis occurs when host pro-inflammatory immune responses become abnormally
elevated due to a dysregulated or aberrant host-response to infection. Diagnostic methods for
sepsis can vary between hospitals, but often involve scoring systems (e.g. APACHE II and SOFA)
that grade the severity of illness in patients. Many of the altered physiological parameters
measured by these scoring systems are not necessarily specific to sepsis, which makes it difficult
to diagnose sepsis in early stages. Timing of a patient’s sepsis diagnosis is often predictive of
their clinical outcome, underlining the need for a more definitive molecular diagnostic test.
However, a recent study found that in the majority (70.1%) of sepsis cases, a specific causal
organism could not be determined, likely due to aggressive antibiotics or localized infections.
Bacterial outer membrane vesicles (OMVs) are attractive diagnostic biomarkers because of: A)
their abundance and ability to circulate throughout the body and pass tissue barriers more easily
than bacteria themselves; B) their robustness - unlike their bacterial cell “parent,” OMVs can
withstand the inundation of broad-spectrum antibiotics; and C) their unique features that could
allow for differentiation between bacterial species.
The objective of this proposal is two-fold: Identify whether bacterial OMVs could be a molecular
diagnostic biomarker for sepsis and develop a rapid approach to isolate them from patient plasma.
We seek to develop a straightforward high-purity and rapid separation technology that effectively
isolates and purifies OMVs from biofluids, including plasma. We will implement a modified
tangential flow filtration approach, similar to those used by biopharma for high-capacity and high-
yield purification, with a new nanopocket membrane that effectively captures and releases
bacterial OMVs with minimal loss. Success of these aims will pave the way for the future
development of a one-step, point-of-care diagnostic test for sepsis using bacterial OMVs as the
molecular biomarker, as well a more complex diagnostic test that more accurately quantifies OMV
levels in the patient’s biofluids to help direct early treatment and reduce mortality. This project will
be led by an interdisciplinary team of experts in identifying potential biomarkers in E. coli;
membranes, materials, and bioseparations; and a critical care physician scientist.