Role of CD64 expression on neutrophils in the diagnosis of sepsis and the prediction of mortality in adult critically ill patients

• We assessed the role of flow cytometry parameters in critically ill patients.
• MFI of CD64 expression on neutrophils has high accuracy for the detection of sepsis.
• No cytometry parameter is superior to Simplified Acute Physiology II in predicting mortality.

Intensive care unit patients who developed systemic inflammatory response syndrome (SIRS) with proven microbial etiology were assigned to the infectious causes (n = 29), while patients with negative cultures and more probable other etiology were assigned to the noninfectious causes (n = 37). Flow cytometry was used to detect the presence of CD64 on neutrophils. The multivariate analysis revealed that KPC-producing Klebsiella pneumoniae rectal colonization and >1.39 mean fluorescence intensity (MFI) of CD64 expression on neutrophils upon day 1 of SIRS were significantly associated with an infectious SIRS. The overall mortality was 29% (19 patients) and was independently associated with Simplified Acute Physiology Score II >44 points and multiple-organ dysfunction syndrome, while appropriate antibiotic treatment was identified as predictor of good prognosis. MFI of CD64 expression on neutrophils showed high sensitivity, specificity, and accuracy in the diagnosis of sepsis but not for the prediction of survival.