Sepsis remains one of the most urgent clinical emergencies in modern healthcare. Each hour of delayed targeted treatment significantly increases patient mortality. For decades, intensive care and emergency clinicians have struggled with the critical challenge of distinguishing sepsis from non-infectious systemic inflammation. Conventional culture tests take days, and traditional inflammatory markers frequently fail to deliver the precision clinicians need at the bedside.
Immunexpress is tackling this diagnostic dilemma with SeptiCyte RAPID, a molecular PCR test that measures the patient’s own immune response to detect sepsis in about an hour. Leading this clinical mission is Chief Medical Officer Dr Roy Davis, whose decades of leadership span neonatal critical care, health system quality, and early warning algorithms. In this executive Q&A, Dr Davis shares his clinical perspective on modern sepsis management, the diagnostic power of host-response technology, and how rapid testing empowers physicians to make timely, confident decisions.
Q: Sepsis diagnosis has historically relied on non-specific inflammatory markers and slow blood cultures. How does measuring the host immune response fundamentally change this diagnostic process?
Dr Roy Davis: A rapid 1-hour host response test to differentiate sepsis from non-infectious systemic inflammation, transforms the clinical workflow for a suspected sepsis patient. By shifting the focus from “finding the bug” to “identifying the patient’s dysregulated immune response it can provide actionable results 24 – 48 hours ahead of a blood culture. The latter also have very low positivity rates (ranging from 15- 42%). While there are several lab tests routinely ordered for a suspected sepsis patient, such as a blood cell count, (CBC), C-reactive protein (CRP) or lactate, these are non-specific biomarkers of infection, inflammation or perfusion respectively. Several studies have demonstrated SeptiCyte RAPID has superior performance to CBC, CRP and lactate to differentiate sepsis from non-infectious systemic inflammation. The transformative power of a highly accurate, fast host response test for sepsis diagnosis is that it can guide clinical decision making during the critical decision window (1-3 hours) for appropriate intervention. Studies show early diagnosis improves clinical outcomes.
,Q: Clinicians in the ICU frequently struggle to distinguish between non-infectious systemic inflammation and active sepsis. How does SeptiCyte RAPID help resolve that uncertainty early in patient care?
Dr Roy Davis: Several multi-site studies have demonstrated that SeptiCyte RAPID has both high sensitivity to rule out sepsis and high specificity to rule in sepsis. These performance characteristics have been clinically validated in various ICU patient cohorts, including those which can be particularly challenging, including patients post-surgery, post-transplant with neutropenic fever, trauma, and pediatric patients. Clinicians often struggle to distinguish sterile post-operative or post-traumatic inflammation from severe infection or sepsis. After major surgery or trauma almost, every patient develops a profound inflammatory response (SIRS), which mimics sepsis. Another critical dilemma can be deciding if a patient has cardiogenic shock or septic shock. SeptiCyte RAPID helps answer this difficult question facing clinicians that care for post-surgery and trauma patients, “is this inflammation or infection/sepsis?”
Q: Earlier in your career, you pioneered electronic surveillance algorithms and early warning tools. How does a molecular test like SeptiCyte RAPID integrate with and enhance hospital surveillance protocols?
Dr Roy Davis: My team in collaboration with Microsoft developed an electronic surveillance program that monitored patients’ vital signs and laboratory tests within the Epic electronic chart. Algorithms were used to assess the risk of possible sepsis and an early warning was sent to the bedside nurse if sepsis was suspected. The process was extremely sensitive but not very specific (i.e. ruling in sepsis) as it used the same non specific data that was available to the physicians at that time. The addition of a sensitive and specific host response test for sepsis, SeptiCyte RAPID, to such electronic surveillance systems would be a game changer.
Q: Sepsis presentations vary widely across vulnerable groups, including neonates, oncology patients, and the immunocompromised. How robust is host-response diagnostic accuracy across these complex populations?
Dr Roy Davis: SeptiCyte RAPID has clinical utility across a heterogeneous patient population, consistently discriminating sepsis vs SIRS in patients, including vulnerable groups such as those with cancer, immunocompromised or with comorbidities e.g. diabetes or kidney disease. This robust performance was published in a multi-site study by Balk et al in 2024 and other studies have confirmed these findings.
Q: From your background in hospital administration and quality improvement, what operational and economic advantages does rapid sepsis discrimination bring to a health system?
Dr Roy Davis: As CMO of a large tertiary hospital a common discussion was the payment denial for patients diagnosed with sepsis whose medical record did not support the diagnosis. The presence of multiple comorbidities, the absence of a positive blood culture and the presence of organ failure, possibly secondary to the comorbidity, often led to this denial. The addition of a host response test to the sepsis bundle that has been shown to have high sensitivity and specificity for the diagnosis of sepsis would impact a number of processes:
- Early appropriate clinical intervention or the consideration of an alternative diagnosis
- Compliance with the CMS sepsis bundle and appropriate compensation
- Early source detection.
- Appropriate antibiotic use.
- Documentation to support appropriate coding.
- Decreased payment denials
Q: Looking at hospital-wide diagnostic pathways, how does the ability to produce a reliable sepsis score in about an hour reshape current antimicrobial stewardship practices?
Dr Roy Davis: When clinicians have greater confidence to rule out infection or sepsis they can avoid administering unnecessary antibiotics and/or a low likelihood of sepsis based upon a host response test might support watchful waiting. In some situations, the clinician might administer antibiotics initially but then de-escalate after 24 -48 hours if other clinical parameters and lab tests do not provide evidence of sepsis. When clinicians cannot distinguish infection from SIRS, antibiotics are frequently started “just in case”. Consequently a more reliable rule out test could support fewer unnecessary antibiotics, reduced anti-microbial resistance, lower drug toxicity and lower costs.
Rapid diagnostic precision is essential to reduce sepsis mortality and optimize critical care resources. By reading the patient’s specific genomic immune response rather than waiting for pathogen growth, clinicians can differentiate sepsis from sterile inflammation in critical early hours. This proactive clarity allows medical teams to deliver life-saving interventions immediately while avoiding unnecessary broad-spectrum antibiotic use.
As health systems face rising patient acuity and operational pressures, integrating fast host-response diagnostics like SeptiCyte RAPID will redefine emergency and intensive care workflows. Transitioning from reactive detection to rapid host-directed insight protects vital hospital resources and safeguards patient outcomes. With proven clinical validation and accelerated turnaround times, Immunexpress provides the clinical standard needed to stop sepsis in its tracks.
To learn more, visit https://immunexpress.com/