PROcalcitonin to SHORTen Antibiotics Duration in PEDiatricICU Patients (ProShort-Ped) Trial

Inclusion Criteria: All patients with laboratory- or image-confirmed severe infection at admission or during stay in pediatric ICU will be eligible for inclusion. \* Definition of laboratory- or image-confirmed severe infection: * Two or more of four signs of inflammation: * Temperature \>38.3℃ or \<36℃ * Heart rate \> 90 beats/min * Respiratory rate \>20 breaths/min or PaCO2 (Arterial pressure of carbon dioxide) \< 32 mmHg * WBC (White Blood Cell count) \> 12,000 cells/mm3, \<4000 cells/mm3, or \>5% band-form WBC * Initial Procalcitonin \> 0.5 ng/mL * Presence of either laboratory or image evidence of infection * Laboratory evidence: Sign of inflammation in urine, CSF (Cerebrospinal Fluid), ascites, pleural effusion or local abscess * Image evidence: Compatible findings on Chest X ray, ultrasound, CT (Computed Tomography), MR image (Magnetic Resonance Image) Exclusion Criteria: * Age greater than 15 years or less than 1 month * Known pregnancy * Expected ICU stay less than 3 days * Neutropenia: ANC (Absolute Neutrophil Count) \<500/mm3 * Specific infections for which long-term antibiotic treatment is strongly recommended: * Lobar pneumonia or empyema * Bacterial meningitis * Osteomyelitis * Infective endocarditis * Local abscess * Mediastinitin