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Diagnostic value of procalcitonin to distinguish monomicrobial blood stream infection with coagulase-negative staphylococci from contamination: a pilot study

Abstract number: o217

Schuetz  P., Mueller  B., Trampuz  A.

Objective: 

Growth of coagulase-negative staphylococci (CNS) in blood cultures does not always indicate a bloodstream infection (BSI). Serum procalcitonin (ProCT) has been shown a useful marker for bacterial infections and for antimicrobial guidance. Therefore, we evaluated the diagnostic value of ProCT to distinguish BSI from contamination with CNS.

Methods: 

From April through August 2005 we prospectively evaluated all patients with growth of CNS in their blood cultures. Patients with bacteremia caused by additional microorganisms (polymicrobial infections) were excluded. An infectious disease specialist classified the patients as having BSI or contamination according to standard clinical and laboratory criteria and blinded to ProCT results. Serum ProCT was measured one day before (day ­1), at the day of blood culture collection (day 0), and on the following day (day +1) using a ultrasensitive immuno-luminometric (functional assay sensitivity < 0.05 ng/ml). Values were compared using the Mann Whitney U test. A receiver operating characteristic (ROC) curve analysis was performed.

Results: 

Of the 40 patients, 21 were excluded due to polymicrobial infection. From the remaining patients, 7 had monomicrobial BSI and 12 had contamination with CNS (Table 1).

Median (range) serum ProCT concentrations (ng/dl) were significantly higher in patients with BSI compared to those with contamination at all three time points. In contrast, CRP values and leukocyte counts were only significantly discriminative at day +1. A ProCT cut-off of 0.1 ng/dl showed a sensitivity of 86%, 100% and 100% and specificity of 60%, 84% and 80% at day –1, day 0 and day +1, respectively.

Conclusion: 

In this pilot study, ProCT was an early, accurate biomarker to distinguish BSI from contamination with CNS. If confirmed in a larger trial, ProCT may prevent unnecessary treatment courses for suspected CNS BSI and guide rapid treatment for those, not yet meeting all criteria for CNS BSI.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
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