A Study to Compare the Efficacy and Safety of Extended and Intermittent Infusion of Beta-lactams in Critically Ill Paediatric Patients

The goal of this clinical trial is to examine the success and safety of administering certain antibiotics (beta-lactams) given in a longer 3-hour infusion to children (0-17 years) who are critically ill and have severe infection. The main question it aims to answer is: Is the longer infusion more effective than the conventional short-term (0.5-hour-long) infusion? Researchers will compare the 3-hour-long infusion group to the 0.5-hour-long infusion group to determine whether the longer infusion can cure the infection earlier and whether it is equally safe. The doses are the same in the two groups. Only the duration differs until the patient receives the antibiotic. Participants will: * be given the required antibiotic drug in a 3-hour-long or in a 0.5 hour-long infusion. * be examined to make sure their blood drug levels are correct. This will require two blood tests. * be treated according to routine care and have examinations and blood tests performed.

Inclusion Criteria: * paediatric patients (0-17 years of age) with suspected or confirmed bacterial infection who are treated in a PICU or NICU and diagnosed with sepsis with a total Phoenix Sepsis Score ≥2 points, and the infection is clinically probable or confirmed by microbiological culture (e.g. from a blood culture, cerebrospinal fluid, urine, trachea, wound, etc.), excluding contamination; * who are receiving β-lactams including meropenem, piperacillin/tazobactam, cefepime and ceftriaxone; * who received the same β-lactam therapy within 24 hours prior to inclusion or started new β-lactam therapy due to clinical deterioration; * written consent of the parent or guardian is obtained. Exclusion Criteria: * palliative care patients; * patients participating in other drug trials; * patients with impaired renal function if dosing modification is required (estimated Glomerular Filtration Rate \[eGFR\]\