Ceftazidime-Avibactam PK/PD and Resistance in Hematology Patients

This is a prospective, single-arm, observational, exploratory clinical study to evaluate whether the standard fixed dose of ceftazidime-avibactam (CAZ-AVI) achieves sufficient drug exposure (pharmacokinetic/pharmacodynamic, or PK/PD targets) in patients with blood cancers (or those undergoing stem cell transplantation). Patients with hematological malignancies are at high risk for severe, drug-resistant Gram-negative bacterial infections due to weakened immune systems. CAZ-AVI is a critical antibiotic used to treat these infections. However, there is limited evidence on whether the standard recommended dose achieves adequate drug concentrations for both ceftazidime and avibactam simultaneously in this specific patient group, and whether low drug exposure drives the development of antibiotic resistance during treatment. This study will enroll 60 participants who are already prescribed CAZ-AVI by their treating physicians based on routine clinical needs. The study will not change or interfere with any clinical treatment decisions. To measure drug levels, 5 small blood samples (about 2-3 mL each) will be collected within one dosing interval after the drug reaches a steady level in the body (typically 48 to 72 hours after starting treatment). Microbiological samples (such as blood cultures or swabs) will also be collected at multiple time points to monitor bacterial clearance and detect any newly developed resistance. Participants will be followed up for clinical outcomes and survival status up to 30 days after the completion of treatment. The primary goal of this study is to determine the percentage of patients who achieve the target drug exposure for both ceftazidime and avibactam simultaneously. The secondary goals are to observe clinical cure rates, bacterial clearance rates, 30-day survival, and the rate of newly induced antibiotic resistance during therapy.