The goal of this clinical trial is to assess the pharmacokinetic (PK) and safety and tolerability of Vaborem (fixed combination of meropenem and vaborbactam) in the paediatric population aged from birth to < 18 years with suspected or confirmed Gram negative infections in need of hospitalisation and intravenous (IV) antibiotic administration.

All participants will receive Vaborem IV every 8 hours to treat the suspected or confirmed Gram negative infections for 10 up to 14 days; switch to stepdown oral antibiotic is allowed after a minimum of 3 days of Vaborem. PK sample collection will occur after at least 6 doses administration.

Participant's clinical conditions will be monitored during the entire duration of the hospitalization and during scheduled visit/s after the completion of the treatment.

Main Inclusion Criteria:

• Written informed consent before initiation of any study-related procedures.
• Male or female, from birth to < 18 years of age, inclusive.
• Require hospitalization and a minimum of 3 days of IV antibiotic treatment for suspected or confirmed Gram negative infection as per Investigator's judgement.
• Gram negative infection, according to diagnostic criteria for complicated urinary tract infection/acute pyelonephritis (cUTI/AP), complicated intra-Abdominal Infections (cIAI), Hospital-Acquired Pneumonia/Ventilator Associated Pneumonia (HAP/VAP), Blood-Stream Infection (BSI).

Main Exclusion Criteria:

• History of any moderate or significant hypersensitivity or allergic reaction to beta-lactam antibiotics or to any component of the investigational medical product.
• Gram negative infection that in the opinion of the Investigator is unlikely to respond to the study treatment.
• In treatment with immunosuppressive agents, valproic acid, or probenecid.