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Open Access Highly Accessed Research article

Procalcitonin levels and bacterial aetiology among COPD patients admitted to the ICU with severe pneumonia: a prospective cohort study

Cédric Daubin1*, Jean-Jacques Parienti2, Sabine Fradin3, Astrid Vabret4, Michel Ramakers1, Nicolas Terzi1, François Freymuth4, Pierre Charbonneau1 and Damien du Cheyron1

Author Affiliations

1 The Department of Medical Intensive Care, Caen University Hospital, 14033 Caen Cedex, France

2 The Department of Infectious Diseases and Biostatistics and Clinical Research, Caen University Hospital, 14033 Caen Cedex, France

3 The Department of Biochemistry, Caen University Hospital, 14033 Caen Cedex, France

4 The Department of Virology, Caen University Hospital, 14033 Caen Cedex, France

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BMC Infectious Diseases 2009, 9:157  doi:10.1186/1471-2334-9-157

Published: 21 September 2009

Abstract

Background

Serum procalcitonin (PCT) is considered useful in predicting the likeliness of developing bacterial infections in emergency setting. In this study, we describe PCT levels overtime and their relationship with bacterial infection in chronic obstructive pulmonary disease (COPD) critically ill patients with pneumonia.

Methods

We conducted a prospective cohort study in an ICU of a University Hospital. All consecutive COPD patients admitted for pneumonia between September 2005 and September 2006 were included. Respiratory samples were tested for the presence of bacteria and viruses. Procalcitonin was sequentially assessed and patients classified according to the probability of the presence of a bacterial infection.

Results

Thirty four patients were included. The PCT levels were assessed in 32/34 patients, median values were: 0.493 μg/L [IQR, 0.131 to 1.471] at the time of admission, 0.724 μg/L [IQR, 0.167 to 2.646] at six hours, and 0.557 μg/L [IQR, 0.123 to 3.4] at 24 hours. The highest PCT (PCTmax) levels were less than 0.1 μg/L in 3/32 (9%) patients and greater than 0.25 μg/L in 22/32 (69%) patients, suggesting low and high probability of bacterial infection, respectively. Fifteen bacteria and five viruses were detected in 15/34 (44%) patients. Bacteria were not detected in patients with PCTmax levels < 0.1 μg/L. In contrast, bacteria were detected in 4/7 (57%) patients estimated unlikely to have a bacterial infection by PCT levels (PCTmax > 0.1 and < 0.25 μg/L).

Conclusion

Based on these results we suggest that a PCT level cut off > 0.1 μg/L may be more appropriate than 0.25 μg/L (previously proposed for non severe lower respiratory tract infection) to predict the probability of a bacterial infection in severe COPD patients with pneumonia. Further studies testing procalcitonin-based antibiotic strategies are needed in COPD patients with severe pneumonia.