Blood marker test distinguishes bacterial from viral fever in infants
A small study presented at the European Emergency Medicine Congress tested a flow cytometry method measuring two infection-related molecules in blood. The approach accurately separated bacterial from viral infections in 60 newborns and young infants with fever or noninfectious conditions. Researchers suggest it could reduce unnecessary antibiotics, lumbar punctures, and hospital admissions.
The study enrolled 60 infants at a pediatric emergency department in Genoa. Some had fever; others had noninfectious conditions. Blood samples were analyzed by flow cytometry, measuring CD64 on neutrophils and CD169 on monocytes. These markers tend to move in opposite directions during bacterial versus viral infection.
Combining the two measurements into a ratio separated groups: average scores were 1.10 for no infection, 0.33 for viral infection, and 16.22 for bacterial infection. The method detected all bacterial cases and had a low false-positive rate. It currently requires specialized laboratory equipment and trained staff, so it is not yet a bedside test.
If validated, this ratio-based test could help clinicians avoid unnecessary antibiotics, lumbar punctures, and hospital stays for febrile infants. Families may face less invasive testing and shorter emergency visits, while health systems could use antibiotics more selectively. The benefit depends on larger studies and on adapting flow cytometry into a practical, widely available format. Newborns and young infants remain the main group affected, along with their caregivers and emergency staff.