Procalcitonin as a diagnostic marker and IL-6 as a prognostic marker for sepsis

The diagnosis and prognosis of sepsis after antimicrobial therapy among systemic inflammatory response syndrome (SIRS) patients were evaluated with the biomarkers procalcitonin (PCT), interleukin-6 (IL-6), C-reactive protein (CRP), erythrocyte sedimentation rate, and white blood cell counts. Among 177 consecutive SIRS patients, 78 exhibited sepsis, with Escherichia coli (23.1%) being the most common pathogen. PCT showed the best diagnostic performance, with 74.4% and 93.7% sensitivity and 86.7% and 75.2% specificity among sepsis and severe sepsis/septic shock patients, respectively. PCT, IL-6, and CRP levels were significantly increased in nonsurvivors compared to survivors. Serial measurements at 0, 12, 24, 48, 72, and 96 h showed that IL-6 showed better kinetics in the survivor group and was decreased in more than 86% of survivors by the second day. PCT can support the diagnosis of bacterial infection, especially in septic shock and severe sepsis patients. IL6 exhibited the better kinetics for monitoring the effectiveness of antibiotic treatment.