The objective of this study is to determine whether continuous infusion of ceftazidime-avibactam (CAZ-AVI) could improve clinical outcomes in critically ill patients compared with intermittent infusion.

This study employs a prospective, open-label, randomized controlled, multicenter clinical trial design comparing "CAZ-AVI continuous infusion" versus "CAZ-AVI intermittent infusion," .The secondary objectives is to observe the clinical cure, Bacterial clearance, the probability of target attainment (PTA) of TDM. etc

Inclusion Criteria:

• 18-85 years old, male or female.
• Patients who are admitted to ICU wards.
• Patients clinically diagnosed with carbapenem-resistant organism (CRO) infections, and has been commenced on targeted therapy with ceftazidime-avibactam.
• One or more organ dysfunction criteria in the previous 24 hours i. MAP < 60 mmHg for at least 1 hour; ii. Vasopressors required for > 4 hours; iii. Respiratory support using supplemental high flow nasal prongs, continuous positive airway pressure, bilevel positive airway pressure or invasive mechanical ventilation for at least 1 hour.

iv. Serum creatinine concentration > 220 μmol/L or >2.49 mg/dL

Exclusion Criteria:

• Patient has a known allergy to ceftazidime-avibactam.
• Patient has received ceftazidime-avibactam for more than 48 hours during current infectious episode.
• Patient is in severe condition or expected to survive for no more than 48 hours.
• Patient who receives lung or heart transplant or stem cell transplant.
• Patient is known or suspected to be pregnant.
• Patient has previously been enrolled in the current study.
• Other conditions which are regarded as inappropriate for enrollment.