Sepsis Test Demonstrates Strong Performance in Post-Cardiac Surgery Patients

Sepsis is difficult to diagnose accurately in patients recovering from major surgery, as infection-related symptoms often overlap with non-infectious systemic inflammatory responses. This challenge is especially pronounced after high-risk cardiac and abdominal procedures, where delayed or incorrect diagnosis can worsen outcomes and lead to unnecessary antibiotic use. New studies now show that a rapid molecular diagnostic test can reliably differentiate sepsis from non-infectious inflammation in these complex clinical settings.

The studies evaluated Immunexpress, Pty Ltd.’s (Seattle, WA, USA) SeptiCyte RAPID, a cartridge-based host-response test that uses RT-PCR to measure gene expression patterns associated with sepsis. The test generates a SeptiScore across defined interpretation bands to support clinical decision-making alongside standard assessments. SeptiCyte RAPID helps differentiate infection-positive (sepsis) from infection-negative systemic inflammation response syndromes in patients with escalating signs and symptoms of critical illness.

Image: The SeptiCyte RAPID cartridge for the Idylla molecular testing system (Photo courtesy of Immunexpress)

The first study examined post-cardiac surgery patients with infective endocarditis or those undergoing elective procedures, while the second prospective, single-center pilot study, involved critically ill patients with occlusive acute mesenteric ischemia undergoing emergency surgery. SeptiCyte RAPID performance was compared with conventional biomarkers, including C-reactive protein and procalcitonin.

In cardiac surgery patients, elevated SeptiScores correlated with greater clinical severity, higher SOFA and SAPS scores, and the need for vasopressor or inotropic support, while negative results in elective surgery patients were not associated with infectious complications. In patients with acute mesenteric ischemia, a SeptiScore below 7.4 excluded infection with 100% negative predictive value and achieved an AUC of 0.93 for detecting peritonitis. Conventional biomarkers failed to reliably discriminate infection in this cohort. The findings were published in the International Journal of Molecular Sciences and the Journal of Critical Care.

Together, the studies add to growing evidence supporting the generalizability of SeptiCyte RAPID across diverse and challenging patient populations, including post-cardiovascular surgery and acute abdominal emergencies. The ability to rapidly rule out infection may support earlier, more accurate sepsis diagnosis and improved antibiotic stewardship. Larger studies are planned to further validate these findings across broader clinical settings.

"It is exciting to see continued clinical research such as these recent studies that validates the performance of SeptiCyte RAPID in differentiating sepsis from bypass induced SIRS in post cardiovascular surgical patients and in a group of patients developing occlusive mesenteric ischemia with secondary sepsis," said Roy Davis, MD, PhD, MHA, Chief Medical Officer of Immunexpress. "We also see a continued pattern of SeptiCyte RAPID outperforming some traditional biomarkers used for discriminating between sepsis and systemic inflammatory response syndrome, such as procalcitonin and C-reactive protein. These data provide further support for the ability of SeptiCyte RAPID to aid healthcare systems in accurate and timely sepsis diagnosis and antibiotic stewardship."

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