[Procalcitonin in the early diagnosis of invasive bacterial infection in febrile infants].
BACKGROUND
Procalcitonin (PCT) it is a new marker of bacterial infection. Because of its shorter half-life and earlier ascent it offers advantages over C-reactive protein (CRP).


OBJECTIVE
To compare the diagnostic performance of PCT in the early detection of invasive bacterial infection in infants with that of CPR.


METHODS
Between January of 1998 and February of 2000 we performed a prospective observational study in the emergency department of infants aged between 1 and 36 months who had been treated for fever and for whom PCT and CRP plasmatic values had been obtained. Plasmatic PCT and PCR values were evaluated and correlated with the final diagnosis. ROC curves for both markers were calculated.


RESULTS
One hundred infants with a mean age of 8.8 months (SD 7.59) were included in four groups of 25 patients each (viral infection, localized bacterial infection, invasive bacterial infection and control group). The mean PCT and CRP values in invasive bacterial infections [PCT: 14.45 ng/mL (SD 27.95) and CRP: 95.10 mg/L (SD 7 2.77)] were significantly higher than in non-invasive infections [PCT: 0.27 ng/mL (SD 0.19) and CRP: 25.67 mg/L (SD 33.04)] but the diagnostic performance of PCT was better. The area under the curve for PCT was 0.95 (SD 0.03), which was significantly higher (p < 0.001) than that obtained for CRP [0.81 (SD 0.05)]. The optimal cut-off for PCT was > 0.4 ng/mL (sensitivity: 95.5 %; specificity: 86.4 %) and that for CRP was > 42.9 mg/L (sensitivity: 75 %; specificity: 81.8 %). In infants who had fever for less than 12 hours (n 30) the area under the curve for PCT was 0.90 (SD 0.06), which was higher (p < 0.001) than that for PCR [0.64 (SD 0.11)]. The optimal cut-off for PCT in this group was > 0.4 ng/mL (sensitivity: 90 %; specificity: 94 %) and that for CRP was > 26.6 mg/L (sensitivity: 60 %; specificity: 77.8 %).


CONCLUSIONS
The diagnostic performance of PCT was higher than that of CRP in the early detection of invasive infection in febrile infants, even when evolution was less than 12 hours.
Fernández López
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Sección de Urgencias Pediátricas. Servicio de Pediatría. Unidad Integrada Hospital Sant Joan de Déu-Clínic. 30775alf@comb.es
Luaces Cubells
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Valls Tolosa
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Ortega Rodríguez
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García García
J J
JJ
Mira Vallet
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Pou Fernández
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D001424:Bacterial Infections / Q000175:diagnosis*; D002116:Calcitonin; D015740:Calcitonin Gene-Related Peptide; D002675:Child, Preschool; D004630:Emergencies; D005334:Fever / Q000209:etiology; D006023:Glycoproteins; D006801:Humans; D007223:Infant; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D011498:Protein Precursors; D012680:Sensitivity and Specificity; D013997:Time Factors
C000606589:CALCA protein, human; D006023:Glycoproteins; D011498:Protein Precursors; D002116:Calcitonin; D015740:Calcitonin Gene-Related Peptide