Bloodstream Infections Caused by Carbapenem-Resistant Enterobacterales: Impact of Ceftazidime-Avibactam Antibiotic Therapy on Lethality

Bloodstream infections (BSIs) caused by carbapenem-resistant Enterobacterales (CRE) are associated with high morbidity and mortality and represent a global public health threat. Antibiotic therapy with ceftazidime-avibactam (CAZ-AVI) is recommended as monotherapy for treatment of CRE producing Ambler class A and D beta-lactamases, and in combination with aztreonam (ATM) for those producing metallo-beta-lactamases (MBL). Despite this, data from randomized clinical trials supporting this strategy are scarce. To evaluate the impact of antibiotic therapy with ceftazidime-avibactam on outcomes of patients with BSI due to CRE in a real-life study, and to describe lethality, epidemiological and clinical characteristics of patients with BSI due to Enterobacterales, identifying the main Enterobacterales isolated, their antimicrobial susceptibility profile, and risk factors for death. Retrospective cohort including cases of BSI due to Enterobacterales from two tertiary hospitals in Salvador, Bahia, during 04/01/2016 to 02/28/2018 and 01/01/2022 to 06/30/2024. Epidemiological data were collected through chart review and bacterial isolates were identified by mass spectrometry and VITEK-2®. Antimicrobial susceptibility was performed by automation. Eighty-nine cases of BSI due to CRE were identified, 75.3% caused by K. pneumoniae . The main carbapenem resistance mechanism identified was serine carbapenemase production (38.2%), followed by metallo-beta-lactamases (31.5%). Overall mortality was 62.9%. When compared with other antimicrobial regimens, antibiotic therapy with CAZ-AVI ± ATM was a protective factor for death (48.4% versus 70.7%, p value = 0.04 and RR = 0.55, 95% CI [0.32–0.96]). Antimicrobial treatment with CAZ-AVI ± ATM was a protective factor for death in adults with BSI due to CRE in two tertiary hospitals in Brazil. Further studies are needed.