Evaluation of circulating host-and pathogen-derived markers of infection and inflammation in the laboratory diagnosis of SEPSIS

Abstract

Patients with sepsis need to be distinguished from those with systemic inflammation due to non-infectious causes (SIRS) so that empiric antimicrobial therapy can be administered timeously to those with sepsis. The current study was designed to evaluate the potential of clinical parameters and circulating biomarkers to distinguish sepsis from SIRS.

Clinical parameters, leukocyte counts and platelets were measured on admission for each patient. Circulating C-reactive protein (CRP), procalcitonin (PCT) and cytokine concentrations were quantified using laser immunonephelometry, immunoluminescence and a Bio-Plex suspension bead array system, respectively. Blood, sputum, urine, peritoneal and cerebrospinal fluid were sent for microscopy and culture. Based on available clinical information and the results of microbiological testing, patients were classified retrospectively into 2 groups, those with sepsis or SIRS.

Of the 62 patients included in the study, 37 and 25 were classified as sepsis and SIRS respectively. Mean body temperature was higher and blood pressure lower in the sepsis patients. Circulating concentrations of CRP, PCT, interleukin (IL)-10 and IL-1 receptor antagonist (IL-1Ra) were significantly higher in patients with sepsis and associated, although not significantly so, with lower levels of IL-1β and IL-8, while decreased platelet counts and increased IL-6 (both p<0.05) and, to a lesser extent, IL-1Ra (not significant) were associated with overall mortality in the combined group of patients.

Relative to patients with SIRS, those with sepsis were found to have increased levels of the immunosuppressive/anti-inflammatory cytokines, IL-Ra and IL-10, consistent with a more intense counteracting anti-inflammatory response.