High plasma level of long pentraxin 3 (PTX3) is associated with fatal disease in bacteremic patients: a prospective cohort study.

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.