Prognostic factors for mortality in critically ill patients with infections caused by carbapenem-resistant gram-negative pathogens treated with ceftazidime–avibactam: a multicenter retrospective study

Carbapenem-resistant Klebsiella pneumoniae (CRKP) and difficult-to-treat resistant Pseudomonas aeruginosa (DTRPA) are major public health concerns due to rising incidence and high mortality rates. We aimed to evaluate clinical outcomes and identify factors associated with 30-day mortality among critically ill patients with these infections treated with ceftazidime–avibactam (CzA) in intensive care units (ICUs). This multicenter, retrospective cohort study was conducted across four tertiary care centers in Türkiye. Adult ICU patients (≥ 18 years) with culture-confirmed CRKP or DTRPA infections who received CzA therapy were included. Patients with recurrent infections, incomplete medical records, or infections caused by other pathogens were excluded. Demographic, clinical, microbiological, and treatment-related data were extracted from electronic health records. The primary outcome was 30-day all-cause mortality. Univariable analyses were performed to screen variables associated with 30-day mortality, followed by multivariable logistic regression to identify independent risk factors. A total of 262 critically ill patients were included. The mean age was 66.4 ± 15.4 years, and 67.6% were male. Septic shock was present in 42.4% of patients, and 24.8% required invasive mechanical ventilation at infection onset. The overall 30-day mortality rate was 34%, with no significant difference between CRKP and DTRPA infections. Mortality was higher among patients with greater disease severity, reflected by higher SOFA scores, the presence of bloodstream infection, and elevated procalcitonin levels. In addition, initiation of CzA therapy more than 72 h after index culture collection was associated with substantially higher mortality compared with initiation within 48–72 h. No significant difference in mortality was observed between patients receiving CzA monotherapy and those receiving combination therapy. In this multicenter cohort of critically ill patients with these infections, mortality was primarily associated with markers of acute disease severity and delayed initiation of active antimicrobial therapy. These findings highlight the clinical importance of timely CzA administration in high-risk ICU populations. Not applicable.