BACKGROUND: Early diagnostic and prognostic stratification of patients with 
suspected infection is a difficult clinical challenge. We studied plasma 
pentraxin 3 (PTX3) upon admission to the emergency department in patients with 
suspected infection.
METHODS: The study comprised 537 emergency room patients with suspected 
infection: 59 with no systemic inflammatory response syndrome (SIRS) and without 
bacterial infection (group 1), 67 with bacterial infection without SIRS (group 
2), 54 with SIRS without bacterial infection (group 3), 308 with sepsis (SIRS 
and bacterial infection) without organ failure (group 4) and 49 with severe 
sepsis (group 5). Plasma PTX3 was measured on admission using a commercial 
solid-phase enzyme-linked immunosorbent assay (ELISA).
RESULTS: The median PTX3 levels in groups 1-5 were 2.6 ng/ml, 4.4 ng/ml, 5.0 
ng/ml, 6.1 ng/ml and 16.7 ng/ml, respectively (p<0.001). The median PTX3 
concentration was higher in severe sepsis patients compared to others (16.7 vs. 
4.9 ng/ml, p<0.001) and in non-survivors (day 28 case fatality) compared to 
survivors (14.1 vs. 5.1 ng/ml, p<0.001). A high PTX3 level predicted the need 
for ICU stay (p<0.001) and hypotension (p<0.001). AUC(ROC) in the prediction of 
severe sepsis was 0.73 (95% CI 0.66-0.81, p<0.001) and 0.69 in case fatality 
(95% CI 0.58-0.79, p<0.001). PTX3 at a cut-off level for 14.1 ng/ml (optimal 
cut-off value for severe sepsis) showed 63% sensitivity and 80% specificity. At 
a cut-off level 7.7 ng/ml (optimal cut-off value for case fatality) showed 70% 
sensitivity and 63% specificity in predicting case fatality on day 28.In 
multivariate models, high PTX3 remained an independent predictor of severe 
sepsis and case fatality after adjusting for potential confounders.
CONCLUSIONS: A high PTX3 level on hospital admission predicts severe sepsis and 
case fatality in patients with suspected infection.