CD64 and CD169 could help differentiate bacterial from viral infections in Emergency Department

Bourgoin, P.; Soliveres, T.; Barbaresi, A.; Loundou, A.; Arnoux, I.; Bernot, D.; Morange, P.-E.; Michelet, P.; Malergue, f.; Markarian, T.

Background: The identification of a bacterial, viral or even non-infectious cause is essential in the management of febrile syndrome in the emergency department (ED) setting, especially in epidemic contexts such as flu or CoVID-19. Objectives: The aim of this study was to assess discriminative performances of two biomarkers, CD64 on neutrophils (nCD64) and CD169 on monocytes (mCD169), using a new flow cytometry procedure, in patients presenting with fever to the ED. Human leucocyte antigen-DR on monocytes (mHLA-DR), HLA-ABC ratio (rHLA-ABC), and CD64 on monocytes (mCD64) were also assessed. Methods: 85 adult patients presenting with potential infection were included during the 2019 flu season in the ED of La Timone Hospital. They were divided into four diagnostic outcomes according to their clinical records: no-infection, bacterial infection, viral infection and co-infection. Results: mCD169 was elevated in patients suffering from Flu A virus or Respiratory Syncytial Virus, while nCD64 was mainly found elevated in subjects with Streptococcus pneumoniae. In total, 38 (45%) patients were diagnosed with bacterial infections, 11 (13%) with viral infections and 29 (34%) with co-infections. nCD64 and mCD169 showed 90% and 80% sensitivity, and 78% and 91% specificity, respectively, for identifying patients with bacterial or viral infections. Other biomarkers had lower discriminative performances. Conclusions: nCD64 and mCD169 have potential for accurately distinguishing bacterial and acute viral infections. Combined in an easy and rapid flow cytometry procedure, they constitute a potential improvement for infection management in the ED setting, and could even help for the triage of patients during emerging epidemics.