Dynamics of C-reactive protein and white blood cell count in critically ill patients with nosocomial Gram positive vs. Gram negative bacteremia: a historical cohort study.

Background: Nosocomial bacteremia is associated with a poor prognosis. Early adequate therapy has been shown to improve outcome. Consequently, rapid detection of a beginning sepsis is therefore of the utmost importance. This historical cohort study was designed to evaluate if different patterns can be observed in either C-reactive protein (CRP) and white blood cell count (WCC) between Gram positive bacteremia (GPB) vs. Gram negative bacteremia (GNB), and to assess the potential benefit of serial measurements of both biomarkers in terms of early antimicrobial therapy initiation.

Methods: A historical study (2003-2004) was conducted, including all adult intensive care unit patients with a nosocomial bacteremia. CRP and WCC count measurements were recorded daily from two days prior (d(-2)) until one day after onset of bacteremia (d(+1)). Delta (Delta) CRP and Delta WCC levels from the level at d-2 onward were calculated.

Results: CRP levels and WCC counts were substantially higher in patients with GNB. Logistic regression analysis demonstrated that GNB and Acute Physiology and Chronic Health Evaluation (APACHE) II score were independently associated with a CRP increase of 5 mg/dL from d-2 to d+1, and both were also independently associated with an increase of WCC levels from d(-2) to d(+1) of 5,000 x 10(3) cells/mm3.

Conclusion: Increased levels of CRP and WCC are suggestive for GNB, while almost unchanged CRP and WCC levels are observed in patients with GPB. However, despite the different patterns observed, antimicrobial treatment as such cannot be guided based on both biomarkers.