Ceftazidime/avibactam (CAZ/AVI) is a new β-lactam drug, which has good antibacterial effect against carbapenem resistant enterobacter. However, previous studies found that CAZ/AVI had a low PK/PD compliance rate after the recommended dose of the drug instructions.Therefore, this study was intended to explore the clinical efficacy of different administration schedules of CAZ/AVI for patients with severe infection, and further analyze the correlation between CAZ/AVI PK/PD parameters and clinical efficacy and adverse reactions.

1. Main purpose The main objective of this study was to verify that the clinical efficacy of treatment group (load dose of 2.5g, then continuous infusion of 2.5gQ8h, the dose can be adjusted according to renal function) with severe infection was superior to that of the control group (standard dose and administration regimen of ceftazidime/avibactam, i.e. 2.5gQ8h, 2h infusion).Dose can be adjusted according to renal function).
2. Secondary purpose (1) To investigate the relationship between different administration regimens and bacterial clearance and 28-d mortality (2) To explore the correlation between different dosing regimens and PK/PD compliance rate (3) To explore the correlation between different administration regimens and adverse drug reactions

Inclusion Criteria:

Multiple-resistant negative bacteria Sensitive to ceftazidime/avibactam Received intravenous infusion of ceftazidime/avibactam

Exclusion Criteria:

Allergic to ceftazidime/avibactam Blood sample not be collected Pregnant or lactating

A non-blind study