Ceftazidime–Avibactam With or Without Aztreonam Versus Other Active Antimicrobials in the Treatment of Bloodstream Infections by Carbapenem-Resistant Klebsiella pneumoniae

Carbapenem-resistant Klebsiella pneumoniae (CRKP) bloodstream infections (BSIs) are associated with high mortality and limited treatment options. Evidence supporting ceftazidime–avibactam, with or without aztreonam, from studies exclusively with BSIs caused by CRKP remains scarce, particularly from Latin America, where there is a high burden of disease. In this study, we compared ceftazidime–avibactam-based regimens with other active antimicrobials (OAA) regimens for healthcare-associated CRKP BSIs in a Brazilian tertiary-care hospital. We conducted a retrospective cohort study including consecutive adult patients with healthcare-associated BSIs caused by CRKP between 2014 and 2024. Patients receiving ceftazidime–avibactam with or without aztreonam were compared with those receiving OAAs. The primary outcome was 30-day all-cause mortality. Secondary outcomes included acute kidney injury (AKI), the composite of death or AKI, and post-BSI length of hospital stay. Multivariable Cox regression was performed. A total of 129 patients were included, of whom 73 received ceftazidime–avibactam-based therapy and 56 received OAAs. Carbapenemase types included class A (82.2%), class B (9.3%), and class A+B co-producing isolates (8.5%). Thirty-day mortality was significantly lower in the ceftazidime–avibactam group than in the OAA group (23.3% vs. 41.1%; P = 0.049). After adjustment, ceftazidime–avibactam-based therapy remained independently associated with lower 30-day mortality (hazard ratio, 0.51; 95% confidence interval, 0.27–0.96; P = 0.04). The composite of death or AKI was also significantly lower with ceftazidime–avibactam-based therapy ( P = 0.047), whereas median post-BSI hospital stay among survivors was 8 days shorter ( P = 0.06). In this cohort, ceftazidime–avibactam with or without aztreonam was independently associated with lower 30-day mortality than OAAs in the treatment of CRKP BSIs. These findings extend the available evidence to BSIs caused by carbapenemase-producing isolates and support the need for broader access to ceftazidime–avibactam-based regimens in low- and middle-income countries, where therapeutic options remain limited.