Efficacy, Pharmacokinetics and Safety of Meropenem in Infants Below 90 Days With Clinical or Confirmed Late-onset Sepsis

Inclusion Criteria: * Informed consent form signed by the parents/carers * Chronological age below 90 days inclusive * Chronological age greater or equal to 72 hours of life at beginning of LOS * Clinical or confirmed sepsis * For infants below 44 weeks inclusive of corrected age clinical sepsis is defined, according to the Expert Meeting on Neonatal and Paediatric Sepsis (Report on the Expert Meeting on Neonatal and Paediatric Sepsis - 8 June 2010, EMA London), as the presence in the last 24 hours of at least * two clinical criteria: * hyper- or hypothermia or temperature instability, * reduced urinary output or hypotension or mottled skin or impaired peripheral perfusion * apnea or increased oxygen requirement or increased requirement for ventilatory support, * bradycardia spells or tachycardia or rhythm instability, * feeding intolerance or abdominal distension, * lethargy or hypotonia or irritability, * skin and subcutaneous lesions such as petechial rash or sclerema, * and two laboratory criteria: * white blood cells (WBC) count \< 4 or \> 20 x 109 cells/L, * immature to total neutrophil ratio (I/T) \> 0.2, * platelet count \< 100 x 109/L, * C-reactive protein (CRP) \> 15 mg/L or procalcitonin ≥ 2 ng/mL, * glucose intolerance when receiving normal glucose amounts (8-15 g/kg/day) as expressed by blood glucose values \> 180 mg/dL or hypoglycemia (\< 40 mg/dL) confirmed at least two times, * acidosis as characterized by base excess (BE) \< -10 mmol/L or lactate with value above 2 mmol/L. confirmed sepsis is defined as positive culture for pathogens in a sample from a normally sterile site and at least one laboratory sign or clinical sign (from the list above) * For children above 44 weeks corrected age clinical sepsis is defined according to the Goldstein criteria (Goldstein et al, 2005) as at least two of the following criteria, one of which must be abnormal temperature or WBC count: * Core temperature of \> 38.5 °C or \< 36 °C; * Tachycardia, defined as mean heart rate \> to the 95th percentile for age group in the absence of external stimulus, chronic drugs, or painful stimuli or unexplained persistent elevation over a 0.5 to 4 hour time period; or bradycardia, defined as a mean heart rate \< to the 5th percentile for age group in the absence of external vagal stimulus, beta blocker drugs, or congenital heart disease or unexplained persistent depression over a 0.5 hour time period; * Mean respiratory rate \> to the 95th percentile for age group or mechanical ventilation for an acute process not related to underlying neuromuscular disease or the receipt of general anaesthesia; * Leukocyte count \< the 5th percentile or \> than the 95th percentile for age group (not secondary to chemotherapy-induced leucopoenia). confirmed sepsis: positive culture for pathogens in a sample from a normally sterile site and at least one laboratory sign or clinical sign (from the list above) Exclusion Criteria: * Administration of any systemic antibiotics for more than 24 hours prior to the randomisation, unless the change is driven by the lack of efficacy of the former regimen; * Severe congenital malformations if the infant is not expected to survive for more than 3 months; * Other situations where the treating physician considers a different antibiotic regimen necessary; * Known intolerance or contraindication to study medication; * Participation in any other clinical study of investigational drugs; * Renal failure (as defined by Akcan-Arikan et al., 2007) and requirement of haemofiltration or peritoneal dialysis; * Confirmed sepsis with microorganisms known to be resistant to study therapies.