EaRly impAct theraPy With Ceftazidime-avibactam Via rapID Diagnostics

Inclusion Criteria: 1. Adult patients aged 18 years or older (21 years or older in Singapore) who meet at least one of the following criteria: * At risk of developing bloodstream infection, hospital-acquired pneumonia (HAP), or ventilator-associated pneumonia (VAP) due to Pseudomonas aeruginosa or carbapenem-resistant Enterobacterales; OR * Blood culture bottles showing Gram-negative bacilli on Gram stain; OR * Suspected HAP or VAP with respiratory specimens showing Gram-negative bacteria on Gram stain. 2. For randomisation, all of the following criteria must be fulfilled: * Written informed consent obtained from the participant or their authorised representative. * An appropriate blood or respiratory specimen received by the participating microbiology laboratory, with Gram-negative bacilli detected on Gram stain. * Patients with HAP or VAP must fulfil the US Centers for Disease Control and Prevention National Healthcare Safety Network (CDC NHSN) criteria. * No exclusion criteria are met. Exclusion Criteria: 1. Refractory shock or comorbid condition such that the patient is not expected to survive more than 48 hours. 2. Suspected catheter-related bloodstream infection where the implicated vascular catheter cannot be removed. 3. Treatment is not intended to cure the infection. 4. Infection requiring prolonged antibiotic treatment (more than two weeks). 5. Incarceration in a correctional facility. 6. Previous enrolment in the RAPID trial within the preceding 60 days. 7. Patients younger than 18 years (younger than 21 years in Singapore).