Infections caused by multidrug-resistant Gram-negative bacilli represent a growing challenge in hospitals, often associated with high mortality rates and the use of antimicrobials with significant toxicity. Ceftazidime-avibactam is a potent and less toxic alternative, particularly in infections caused by carbapenemase-producing Enterobacterales. This study aimed to identify factors associated with 30-day mortality among patients treated with ceftazidime-avibactam in a public university hospital.

A retrospective cohort study included adult inpatients between 2022 and 2024 with documented infection by carbapenem-resistant Gram-negative bacilli, treated with intravenous ceftazidime-avibactam for at least 48 hours. Patients with incomplete data were excluded. Variables included demographics, Charlson comorbidity score, NEWS-2 severity score, etiologic agent, infection type, clinical justification, treatment duration, and 30-day mortality. Multivariate logistic regression with backward stepwise selection was used.

The cohort included 277 patients, median age 60 years (IQR 48–69), predominantly male (63%). Thirty-day mortality was 30.5%. Independent predictors of death were male sex (OR 2.15; 95%CI: 1.13–4.20), higher Charlson comorbidity score (OR 1.20; 95%CI: 1.06–1.38), and higher NEWS-2 score (OR 1.32; 95%CI: 1.21–1.45). The final model showed good discrimination (AUC = 0.81).

Thirty-day mortality among patients treated with ceftazidime-avibactam was high, reflecting case severity. Male sex, higher comorbidity burden, and greater admission severity were independent predictors of poorer outcomes. These findings underscore the importance of integrated clinical assessment and the therapeutic potential of ceftazidime-avibactam in managing severe infections caused by multidrug-resistant Gram-negative bacilli.