Impact of ceftazidime avibactam on colonization by carbapenem resistant Enterobacterales during treatment of related infections.

Carbapenem-resistant Enterobacterales (CRE), particularly carbapenem-resistant Klebsiella pneumoniae (CRKP) and carbapenem-resistant Escherichia coli (CREC), are significant pathogens causing healthcare-associated infections. This retrospective study assesses the effectiveness of ceftazidime-avibactam (CAZ/AVI) in achieving perianal swab (PAS) negativity compared to other treatments, including colistin, polymyxin B, meropenem, and combinations with fosfomycin. We retrospectively analyzed 147 CRE-colonized patients (76 females) screened with PAS samples from January 14, 2021, to April 27, 2024. Patients were divided into two groups: those treated with CAZ/AVI (n = 40) and those receiving alternative treatments (n = 44) for bloodstream infections or ventilator associated pneumonia caused by CRE. PAS negativity was defined as conversion from positive to negative, while relapse was a positive PAS result after initial negativity. A p-value below 0.05 was considered to be statistically significant. The CAZ/AVI group achieved a higher rate of PAS negativity (32 patients) with a median time to PAS negativity of 1 week. Relapse rates were similar between CAZ/AVI (23/24) and non-CAZ/AVI groups (8/10). Significant differences in PAS negativity were observed at two weeks (p < 0.001) but not at four weeks (p = 0.492). The median time to PAS negativity was shorter in the CAZ/AVI group (1 week) compared to the non-CAZ/AVI group (2 weeks; p = 0.027). CAZ/AVI is more effective than alternative treatments for short-term PAS negativity, but relapse rates are comparable, highlighting challenges in long-term CRE management. Continuous surveillance and personalized decolonization strategies are essential. Further research is needed to investigate relapse mechanisms and evaluate combination therapies or novel strategies for sustained decolonization.