Procalcitonin and C-Reactive Protein Levels According to Blood Culture Results in Intensive Care Unit Patients

Comparative diagnostic test evaluation of serum procalcitonin and C-reactive protein in suspected bloodstream infections in children with cancer

PURPOSE

To compute diagnostic test properties of C-reactive protein (CRP) and serum procalcitonin (PCT) levels in bloodstream infections in children with cancer and suspected sepsis, in comparison with blood culture as the gold standard.

METHODOLOGY

Consecutive paediatric cancer patients, aged ≤14 years, with clinically suspected bloodstream infections were evaluated with blood culture and assay of PCT and CRP levels. Blood culture was taken as the gold standard for comparison. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), likelihood ratio (LR) and receiver operating characteristic (ROC) with area under ROC curve (AUC) were calculated to assess the diagnostic test performance for PCT and CRP.Results/Key findings. The ROC curve for PCT was better than that for CRP, with an AUC of 0.751 for PCT at a cut-off of 2.25 ng ml-1. The AUC for CRP was 0.638 at a cut-off of 8.0 mg dl-1. Among the three cut-off values of PCT selected from the ROC curve applicable to the patients under study, the cut-off value of ≥0.49 ng ml-1 had the maximum sensitivity of 81.4 % and an NPV of 94.67 %; ≥2.25 ng ml-1 had a sensitivity and specificity of 65.12 and 71.6 %, respectively, and ≥6.47 ng ml-1 had a maximum specificity of 82.10 %. For CRP, the cut-off value of ≥5.3 mg dl-1 had the maximum sensitivity of 72.09 %; ≥8.0 mg dl-1 had a sensitivity and specificity of 58.14 and 68.09 %, respectively, and ≥8.4 mg dl-1 had the maximum specificity of 70.04 %.

CONCLUSION

PCT is a better serological marker for excluding bloodstream infections than CRP. The cut-off value of 0.49 ng ml-1 with a negative predictive value of 94.67 % will be ideal in a clinical setting of immune-compromised children with suspected sepsis.

Comparative Study of Plasma Endotoxin with Procalcitonin Levels in Diagnosis of Bacteremia in Intensive Care Unit Patients

BACKGROUND

Both procalcitonin (PCT) and plasma endotoxin levels cannot be solely used for a definite diagnosis of bacteremia or sepsis, and there has been few study comparing the values of the two biomarkers for the diagnosis of bacteremia. The aim of this study was to identify bacteria causing bacteremia and evaluate the role of the two biomarkers in the diagnosis of bacteremia in Intensive Care Unit (ICU).

METHODS

The medical records of 420 patients in ICU were retrospectively reviewed. Patients (n = 241) who met the inclusion criteria were subjected to blood culture (BC) for the analysis of the endotoxin or PCT levels. The exclusion criteria included the presence of infection with human immunodeficiency virus and/or AIDS, neutropenia without sepsis, pregnancy, treatment with immunosuppressive therapies, or blood diseases such as hematological tumors. Patients' BC episodes were divided into BC negative, Gram-negative (GN) bacteria, Gram-positive bacteria, and fungi groups. The PCT and plasma endotoxin levels were compared in the different groups.

RESULTS

A total of 241 patients with 505 episodes of BC were analyzed. The GN bacteria group showed higher levels of PCT and endotoxin than the BC negative, Gram-positive bacteria, and fungi groups. GN bacteremia was more prevalent than Gram-positive bacteremia. The GN bacteremia caused by non-Enterobacteriaceae infection presented higher endotoxin level than that by Enterobacteriaceae, but no significant difference in PCT levels was observed between the two groups. The plasma endotoxin significantly differed among different groups and was bacterial species dependent.

CONCLUSIONS

Plasma endotoxin was more related to GN than to Gram-positive bacteremia, and that endotoxin level was species dependent, but PCT level remained relatively more stable within the GN bacteria caused bacteremia. Both GN and positive bacteria caused bacteremia in the ICU patients in different regions of China. And PCT is a more valuable biomarker than endotoxin in the diagnosis of bacteremia.