Diagnostic role of CD64 expression on neutrophils as biomarker for blood stream infection in liver cirrhosis: some preliminary findings

Background: The expression of CD64 on neutrophils (nCD64), measured using flow cytometry, has been proposed as a biomarker for bloodstream infections (BSI). However, data regarding its use in the setting of liver cirrhosis are lacking. Methods: We compared nCD64 levels in 15 cirrhotic patients with BSI to those in 19 controls, including outpatients with stable decompensated cirrhosis without infection. Additionally, we compared nCD64 with C-reactive protein (CRP) and procalcitonin (PCT) in infected hospitalized cirrhotic patients. Results: Cirrhotic patients with infection had higher levels of nCD64 compared to controls (6.0 [5.4-7.1] vs. 2.0 [1.5-2.2]; p<0.001). Among infected patients, a correlation between nCD64 (AUC=0.934 [0.875-0.982 95% CI]), CRP (AUC=0.972 [0.942-0.993 95% CI]), and PCT (AUC=0.859 [0.739-0.953 95% CI]) was observed. However, in our sample of cirrhotic individuals, nCD64 values were not significantly different between patients with worse prognosis and those with positive outcomes (p=0.448), and its expression was not influenced by Gram stain. Conclusions: In our cohort, nCD64 appears to be a promising new biomarker for BSI. Additional prospective studies are needed to confirm its role and limitations in conjunction with other biomarkers and rapid microbiology in the diagnostic multidisciplinary pathway for septic cirrhotic patients.