Bedside Therapeutic Monitoring of β-Lactam Levels in Newborns, Children and Adolescents Admitted to Intensive Care.

Inclusion Criteria: * Age younger than 18 years * Newborns (preterm or not) in neonatal intensive care * Infants, children, and adolescents in pediatric intensive care * Clinically suspected or microbiologically proven sepsis that might be associated with ventilator-associated pneumonia or otherwise associated with health care * Need for antibiotic treatment by piperacillin-tazobactam, ceftazidime, or meropenem of intermittent administration * Informed consent form signed by parents/guardian * Informed consent form signed by patients old enough to understand. Exclusion Criteria: * Process for active limitation of treatment underway * Suspected or known hypersensitivity to studied beta-lactams * Renal failure, defined as serum creatinine \> 1.5 mg/dl or urine production \< 0.3 ml/kg for 24 h or anuria for 12 h. * Co-administration of two β-lactam antibiotics * Cystic fibrosis * No national health insurance coverage in French center * Family unable to understand study-related information due to language or other communication issues * No consent obtained