Procalcitonine et marqueurs de l'infection dans les pneumonies communautaires de l'enfant

Objective – To assess the importance of procalcitonin (PCT) in pneumonia, PCT was compared to other blood markers, C-reactive protein (CRP), interleukin 6 (IL6), and interferon-alpha (INFα). This prospective study was performed in the emergency room on 88 children (two months–13 years) hospitalized for severe community-acquired pneumonia.Patients – S. Pneumoniae was isolated in ten patients' blood culture, 15 patients a probable bacterial pneumonia according to sputum analysis (14 S. Pneumoniae, 1 Haemophilus influenza b), ten patients a Mycoplasma pneumoniae infection, and 37 others were infected with viruses, eight of whom with a bacterial co-infection. In 16 patients, no causal agent was identified.Results – PCT was always > 2 μg/L in the ten patients with blood culture positive for S. pneumoniae and CRP was > 60 mg/L in 8/10. PCT was > 1 μg/L in 86% of all patients with probable bacterial infection (including Mycoplasma). CRP concentrations of 20 mg/L had a similar sensitivity but a much lower specificity than PCT (40% vs. 86%) to discriminate between bacterial and viral causes of pneumonia. Specificity and sensitivity of IL6 were lower in all cases. Interferon-alpha is a good marker of viral pneumonia but biological assessment requires two days or more.Conclusions – PCT concentrations, with a threshold of 1 μg/L provides better sensitivity and specificity in emergency room than CRP, IL6, INFα, or white blood cell count to differentiate bacterial and viral causes of community-acquired pneumonia in hospitalized children.