Procalcitonin (PCT) is useful in predicting the bacterial origin of an acute circulatory failure in critically ill patients

Objective: To evaluate the accuracy of procalcitonin (PCT) in predicting bacterial infection in ICU medical and surgical patients.¶Setting: A 10-bed medical surgical unit.¶Design: PCT, C-reactive protein (CRP), interleukin 6 (IL-6) dosages were sampled in four groups of patients: septic shock patients (SS group), shock without infection (NSS group), patients with systemic inflammatory response syndrome related to a proven bacterial infection (infect. group) and ICU patients without shock and without bacterial infection (control group).¶Results: Sixty patients were studied (SS group: n = 16, NSS group, n = 18, infect. group, n = 16, control group, n = 10). The PCT level was higher in patients with proven bacterial infection (72 - 153 ng/ml vs 2.9 - 10 ng/ml, p = 0.0003). In patients with shock, PCT was higher when bacterial infection was diagnosed (89 ng/ml - 154 vs 4.6 ng/ml - 12, p = 0.0004). Moreover, PCT was correlated with severity (SAPS: p = 0.00005, appearance of shock: p = 0.0006) and outcome (dead: 71.3 g/ml, alive: 24.0 g/ml, p = 0.006). CRP was correlated with bacterial infection (p < 10^-5) but neither with SAPS nor with day 28 mortality. IL-6 was correlated with neither infection nor day 28 mortality but was correlated with SAPS. Temperature and white blood cell count were unable to distinguish shocked patients with or without infection. Finally, when CRP and PCT levels were introduced simultaneously in a stepwise logistic regression model, PCT remained the unique marker of infection in patients with shock (PCT S 5 ng/ml, OR: 6.2, 95 %CI: 1.1-37, p = 0.04).¶Conclusion: The increase of PCT is related to the appearance and severity of bacterial infection in ICU patients. Thus, PCT might be an interesting parameter for the diagnosis of bacterial infections in ICU patients.