INTRODUCTION: Long pentraxin 3 (PTX3) is an acute-phase protein secreted by 
various cells, including leukocytes and endothelial cells. Like C-reactive 
protein (CRP), it belongs to the pentraxin superfamily. Recent studies indicate 
that high levels of PTX3 may be associated with mortality in sepsis. The 
prognostic value of plasma PTX3 in bacteremic patients is unknown.
METHODS: Plasma PTX3 levels were measured in 132 patients with bacteremia caused 
by Staphylococcus aureus, Streptococcus pneumoniae, β-hemolytic streptococcae 
and Escherichia coli, using a commercial solid-phase enzyme-linked immunosorbent 
assay (ELISA). Values were measured on days 1-4 after positive blood culture, on 
day 13-18 and on recovery.
RESULTS: The maximum PTX3 values on days 1-4 were markedly higher in 
nonsurvivors compared to survivors (44.8 vs 6.4 ng/ml, p<0.001) and the AUC(ROC) 
in the prediction of case fatality was 0.82 (95% CI 0.73-0.91). PTX3 at a 
cut-off level of 15 ng/ml showed 72% sensitivity and 81% specificity for fatal 
disease. High PTX3 (>15 ng/ml) was associated with hypotension (MAP <70 mmHg)(OR 
7.9;95% CI 3.3-19.0) and high SOFA score (≥4)(OR 13.2; 95% CI 4.9-35.4). The CRP 
level (maximum value on days 1 to 4) did not predict case fatality at any 
cut-off level in the ROC curve (p = 0.132). High PTX3 (>15 ng/ml) remained an 
independent risk factor for case fatality in a logistic regression model 
adjusted for potential confounders.
CONCLUSIONS: PTX3 proved to be a specific independent prognostic biomarker in 
bacteremia. PTX3 during the first days after diagnosis showed better prognostic 
value as compared to CRP, a widely used biomarker in clinical settings. PTX3 
measurement offers a novel opportunity for the prognostic stratification of 
bacteremia patients.