The development of antimicrobial resistance is a natural evolutionary phenomenon of bacteria and is exacerbated by intensive antibiotic use in health care, agriculture, and livestock, making infections harder to treat. This study aims to analyze factors associated with 30-day survival in oncologic patients infected with carbapenem-resistant Gram-negative bacteria (CRGNB).

Multicenter retrospective cohort study of cancer patients >17 years admitted to five centers in the states of São Paulo and Espírito Santo, Brazil, between January 2022 and December 2023, who received at least 48 hours of effective antibiotic therapy for CRGNB infections. Patients with polymicrobial infections were excluded. The outcome was death within 30 days after infection. Bi- and multivariate analyses were performed using Cox regression, and proportional hazard assumptions were assessed using Schoenfeld residual plots. Variables with p < 0.1 in bivariate analysis or with clinical/biological plausibility were included in the multivariate model. Those that reduced the −2 log-likelihood or had p ≤ 0.05 were retained in the final model.

A total of 126 patients were included (mean age 60.9 ± 14.7 years); most (75.4%) had infections due to Enterobacterales, while Pseudomonas spp. (15.1%) and Acinetobacter baumannii complex (9.5%) were less frequent. The most common infectious foci were bloodstream infection (35.7%), pneumonia (25.4%), and urinary tract infections (15.1%). The 30-day survival rate was 57.1%. In multivariate analysis, factors associated with risk of death were age (HR = 1.044; p < 0.001), metastasis (HR = 2.186; p = 0.010), cirrhosis (HR = 14.677; p = 0.014), SOFA score (HR = 1.145; p < 0.001), and combination antibiotic therapy (HR = 2.216; p = 0.008). Shorter time to initiation of effective antibiotic therapy (HR = 0.803; p < 0.001) and pyelonephritis as the infectious focus (HR = 0.199; p = 0.005) were protective factors.

Thirty-day mortality among oncologic patients infected with CRGNB was high and influenced by factors related to infection severity, underlying disease burden, and antibiotic management. These findings reinforce the importance of rapid diagnosis and early treatment of infections in high-risk populations.